scons(1) - Man pages

SCONS(1) SCons __VERSION__ SCONS(1)

NAME
scons - a software construction tool

SYNOPSIS
scons [options...] [name=val...] [targets...]

DESCRIPTION
scons orchestrates the construction of software (and other tangible
products such as documentation files) by determining which component
pieces must be built or rebuilt and invoking the necessary commands to
build them. SCons offers many features to improve developer
productivity such as parallel builds, caching of build artifacts,
automatic dependency scanning, and a database of information about
previous builds so details do not have to be recalculated each run.

scons requires Python 3.6 or later to run; there should be no other
dependencies or requirements. unless the experimental Ninja tool is
used.
Support for Python 3.5 is removed since SCons 4.3.0. The CPython
project has retired 3.5: https://www.python.org/dev/peps/pep-0478.

You set up an SCons build system by writing a script that describes
things to build (targets), and, if necessary, the rules to build those
files (actions). SCons comes with a collection of Builder methods
which apply premade actions for building many common software
components such as executable programs, object files and libraries, so
that for many software projects, only the targets and input files
(sources) need be specified in a call to a builder. SCons thus can
operate at a level of abstraction above that of pure filenames. For
example if you specify a library target named "foo", SCons keeps track
of the actual operating system dependent filename (such as libfoo.so on
a GNU/Linux system), and how to refer to that library in later
construction steps that want to use it, so you don't have to specify
that precise information yourself. SCons can also scan automatically
for dependency information, such as header files included by source
code files (for example, #include preprocessor directives in C or C++
files), so these implicit dependencies do not have to be specified
manually. SCons supports the ability to define new scanners to support
additional input file types.

Information about files involved in the build, including a
cryptographic hash of the contents, is cached for later reuse. By
default this hash (the content signature) is used to determine if a
file has changed since the last build, but this can be controlled by
selecting an appropriate Decider function. Implicit dependency files
are also part of out-of-date computation. The scanned implicit
dependency information can optionally be cached and used to speed up
future builds. A hash of each executed build action (the build
signature is cached, so that changes to build instructions (changing
flags, etc.) or to the build tools themselves (new version) can also
trigger a rebuild.

When invoked, scons looks for a file named SConstruct in the current
directory and reads the build configuration from that file (other names
are allowed, see the section called “SConscript Files” for more
information). The SConstruct file may specify subsidiary configuration
files by calling the SConscript function. By convention, these
subsidiary files are named SConscript, although any name may be used.
As a result of this naming convention, the term SConscript files is
used to refer generically to the complete set of configuration files
for a project (including the SConstruct file), regardless of the actual
file names or number of such files.

Before reading the SConscript files, scons looks for a directory named
site_scons in various system directories and in the directory
containing the SConstruct file or, if specified, the directory from the
--site-dir option instead, and prepends the ones it finds to the Python
module search path (sys.path), thus allowing modules in such
directories to be imported in the normal Python way in SConscript
files. For each found site directory, (1) if it contains a file
site_init.py that file is evaluated, and (2) if it contains a directory
site_tools the path to that directory is prepended to the default
toolpath. See the --site-dir and --no-site-dir options for details on
default paths and controlling the site directories.

SConscript files are written in the Python programming language,
although it is normally not necessary to be a Python programmer to use
scons effectively. SConscript files are invoked in a context that makes
the facilities described in this manual page available in their local
namespace without any special steps. Standard Python scripting
capabilities such as flow control, data manipulation, and imported
Python libraries are available to use to handle complicated build
situations. Other Python files can be made a part of the build system,
but they do not automatically have the SCons context and need to import
it if they need access (described later).

scons reads and executes all of the included SConscript files before it
begins building any targets. To make this clear, scons prints the
following messages about what it is doing:

$ scons foo.out
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cp foo.in foo.out
scons: done building targets.
$

The status messages (lines beginning with the scons: tag) may be
suppressed using the -Q option.

To assure reproducible builds, SCons uses a restricted execution
environment for running external commands used to build targets, rather
then propagating the full environment in effect at the time scons was
called. This helps avoid problems like picking up accidental settings,
temporary debug values that are no longer needed, or one developer
having different settings than another (or than the CI/CD pipeline).
Environment variables that are needed for proper operation of such
commands need to be set explicitly, which can be done either by
assigning the desired values, or by picking values individually out of
environment variables using the Python os.environ dictionary. The
execution environment for a given construction environment is contained
in its $ENV construction variable. A few environment variables are
picked up automatically - see the section called “ENVIRONMENT”).

In particular, if the compiler or other commands that you want to use
to build your target files are not in standard system locations, scons
will not find them unless you explicitly include the locations into the
PATH element of the execution environment. One example approach is to
extract the entire PATH environment variable and set that into the
execution environment:

import os
env = Environment(ENV={'PATH': os.environ['PATH']})

Similarly, if the commands use specific external environment variables
that scons does not recognize, they can be propagated into the
execution environment:

import os

env = Environment(
ENV={
'PATH': os.environ['PATH'],
'ANDROID_HOME': os.environ['ANDROID_HOME'],
'ANDROID_NDK_HOME': os.environ['ANDROID_NDK_HOME'],
}
)

Or you may explicitly propagate the invoking user's complete external
environment:

import os
env = Environment(ENV=os.environ.copy())

This comes at the expense of making your build dependent on the user's
environment being set correctly, but it may be more convenient for many
configurations. It should not cause problems if done in a build setup
which tightly controls how the environment is set up before invoking
scons, as in many continuous integration setups.

scons is normally executed in a top-level directory containing an
SConstruct file. When scons is invoked, the command line (including the
contents of the SCONSFLAGS environment variable, if set) is processed.
Command-line options (see the section called “OPTIONS”) are consumed.
Any variable argument assignments are collected, and remaining
arguments are taken as targets to build.

Values of variables to be passed to the SConscript files may be
specified on the command line:

scons debug=1

These variables are available through the ARGUMENTS dictionary, and can
be used in the SConscript files to modify the build in any way:

if ARGUMENTS.get('debug', 0):
env = Environment(CCFLAGS='-g')
else:
env = Environment()

The command-line variable arguments are also available in the ARGLIST
list, indexed by their order on the command line. This allows you to
process them in order rather than by name, if necessary. Each ARGLIST
entry is a tuple containing (argname, argvalue).

See the section called “Command-Line Construction Variables” for more
information.

scons can maintain a cache of target (derived) files that can be shared
between multiple builds. When derived-file caching is enabled in an
SConscript file, any target files built by scons will be copied to the
cache. If an up-to-date target file is found in the cache, it will be
retrieved from the cache instead of being rebuilt locally. Caching
behavior may be disabled and controlled in other ways by the
--cache-force, --cache-disable, --cache-readonly, and --cache-show
command-line options. The --random option is useful to prevent multiple
builds from trying to update the cache simultaneously.

By default, scons searches for known programming tools on various
systems and initializes itself based on what is found. On Windows
systems which identify as win32, scons searches in order for the
Microsoft Visual C++ tools, the MinGW tool chain, the Intel compiler
tools, and the PharLap ETS compiler. On Windows system which identify
as cygwin (that is, if scons is invoked from a cygwin shell), the order
changes to prefer the GCC toolchain over the MSVC tools. On OS/2
systems, scons searches in order for the OS/2 compiler, the GCC tool
chain, and the Microsoft Visual C++ tools, On SGI IRIX, IBM AIX,
Hewlett Packard HP-UX, and Oracle Solaris systems, scons searches for
the native compiler tools (MIPSpro, Visual Age, aCC, and Forte tools
respectively) and the GCC tool chain. On all other platforms, including
POSIX (Linux and UNIX) platforms, scons searches in order for the GCC
tool chain, and the Intel compiler tools. These default values may be
overridden by appropriate setting of construction variables.

Target Selection
SCons acts on the selected targets, whether the requested operation is
build, no-exec or clean. Targets are selected as follows:

1. Targets specified on the command line. These may be files,
directories, or phony targets defined using the Alias function.
Directory targets are scanned by scons for any targets that may be
found with a destination in or under that directory. The targets
listed on the command line are made available in the
COMMAND_LINE_TARGETS list.

2. If no targets are specified on the command line, scons will select
those targets specified in the SConscript files via calls to the
Default function. These are known as the default targets, and are
made available in the DEFAULT_TARGETS list.

3. If no targets are selected by the previous steps, scons selects the
current directory for scanning, unless command-line options which
affect the target scan are detected (-C, -D, -u, -U). Since targets
thus selected were not the result of user instructions, this target
list is not made available for direct inspection; use the
--debug=explain option if they need to be examined.

4. scons always adds to the selected targets any intermediate targets
which are necessary to build the specified ones. For example, if
constructing a shared library or dll from C source files, scons
will also build the object files which will make up the library.

To ignore the default targets specified through calls to Default and
instead build all target files in or below the current directory
specify the current directory (.) as a command-line target:

scons .

To build all target files, including any files outside of the current
directory, supply a command-line target of the root directory (on POSIX
systems):

scons /

or the path name(s) of the volume(s) in which all the targets should be
built (on Windows systems):

scons C:\ D:\

A subset of a hierarchical tree may be built by remaining at the
top-level directory (where the SConstruct file lives) and specifying
the subdirectory as the target to build:

scons src/subdir

or by changing directory and invoking scons with the -u option, which
traverses up the directory hierarchy until it finds the SConstruct
file, and then builds targets relatively to the current subdirectory
(see also the related -D and -U options):

cd src/subdir
scons -u .

In all cases, more files may be built than are requested, as scons
needs to make sure any dependent files are built.

Specifying "cleanup" targets in SConscript files is usually not
necessary. The -c flag removes all selected targets:

scons -c .

to remove all target files in or under the current directory, or:

scons -c build export

to remove target files under build and export.

Additional files or directories to remove can be specified using the
Clean function in the SConscript files. Conversely, targets that would
normally be removed by the -c invocation can be retained by calling the
NoClean function with those targets.

scons supports building multiple targets in parallel via a -j option
that takes, as its argument, the number of simultaneous tasks that may
be spawned:

scons -j 4

builds four targets in parallel, for example.

OPTIONS
In general, scons supports the same command-line options as GNU Make
and many of those supported by cons.

-b
Ignored for compatibility with non-GNU versions of Make

-c, --clean, --remove
Set clean mode. Clean up by removing the selected targets, well as
any files or directories associated with a selected target through
calls to the Clean function. Will not remove any targets which are
marked for preservation through calls to the NoClean function.

While clean mode removes targets rather than building them, work
which is done directly in Python code in SConscript files will
still be carried out. If it is important to avoid some such work
from taking place in clean mode, it should be protected. An
SConscript file can determine which mode is active by querying
GetOption, as in the call if GetOption("clean"):

--cache-debug=file
Write debug information about derived-file caching to the specified
file. If file is a hyphen (-), the debug information is printed to
the standard output. The printed messages describe what
signature-file names are being looked for in, retrieved from, or
written to the derived-file cache specified by CacheDir.

--cache-disable, --no-cache
Disable derived-file caching. scons will neither retrieve files
from the cache nor copy files to the cache. This option can be used
to temporarily disable the cache without modifying the build
scripts.

--cache-force, --cache-populate
When using CacheDir, populate a derived-file cache by copying any
already-existing, up-to-date derived files to the cache, in
addition to files built by this invocation. This is useful to
populate a new cache with all the current derived files, or to add
to the cache any derived files recently built with caching disabled
via the --cache-disable option.

--cache-readonly
Use the derived-file cache, if enabled, to retrieve files, but do
not not update the cache with any files actually built during this
invocation.

--cache-show
When using a derived-file cache show the command that would have
been executed to build the file (or the corresponding *COMSTR
contents if set) even if the file is retrieved from cache. Without
this option, scons shows a cache retrieval message if the file is
fetched from cache. This allows producing consistent output for
build logs, regardless of whether a target file was rebuilt or
retrieved from the cache.

--config=mode
Control how the Configure call should use or generate the results
of configuration tests. mode should be one of the following
choices:

auto
SCons will use its normal dependency mechanisms to decide if a
test must be rebuilt or not. This saves time by not running the
same configuration tests every time you invoke scons, but will
overlook changes in system header files or external commands
(such as compilers) if you don't specify those dependecies
explicitly. This is the default behavior.

force
If this mode is specified, all configuration tests will be
re-run regardless of whether the cached results are out of
date. This can be used to explicitly force the configuration
tests to be updated in response to an otherwise unconfigured
change in a system header file or compiler.

cache
If this mode is specified, no configuration tests will be rerun
and all results will be taken from cache. scons will report an
error if --config=cache is specified and a necessary test does
not have any results in the cache.

-C directory, --directory=directory
Run as if scons was started in directory instead of the current
working directory. That is, change directory before searching for
the SConstruct, Sconstruct, sconstruct, SConstruct.py,
Sconstruct.py or sconstruct.py file or doing anything else. When
multiple -C options are given, each subsequent non-absolute -C
directory is interpreted relative to the preceding one. This option
is similar to using -f directory/SConstruct, but -f does not search
for any of the predefined SConstruct names in the specified
directory. See also options -u, -U and -D to change the SConstruct
search behavior when this option is used.

-D
Works exactly the same way as the -u option except for the way
default targets are handled. When this option is used and no
targets are specified on the command line, all default targets are
built, whether or not they are below the current directory.

--debug=type[,type...]
Debug the build process. type specifies the kind of debugging info
to emit. Multiple types may be specified, separated by commas. The
following types are recognized:

action-timestamps
Prints additional time profiling information. For each command,
shows the absolute start and end times. This may be useful in
debugging parallel builds. Implies the --debug=time option.

Available since scons 3.1.

count
Print how many objects are created of the various classes used
internally by SCons before and after reading the SConscript
files and before and after building targets. This is not
supported when SCons is executed with the Python -O (optimized)
option or when the SCons modules have been compiled with
optimization (that is, when executing from *.pyo files).

duplicate
Print a line for each unlink/relink (or copy) of a variant file
from its source file. Includes debugging info for unlinking
stale variant files, as well as unlinking old targets before
building them.

explain
Print an explanation of why scons is deciding to (re-)build the
targets it selects for building.

findlibs
Instruct the scanner that searches for libraries to print a
message about each potential library name it is searching for,
and about the actual libraries it finds.

includes
Print the include tree after each top-level target is built.
This is generally used to find out what files are included by
the sources of a given derived file:

$ scons --debug=includes foo.o

memoizer
Prints a summary of hits and misses using the Memoizer, an
internal subsystem that counts how often SCons uses cached
values in memory instead of recomputing them each time they're
needed.

memory
Prints how much memory SCons uses before and after reading the
SConscript files and before and after building targets.

objects
Prints a list of the various objects of the various classes
used internally by SCons.

pdb
Re-run scons under the control of the pdb Python debugger.

prepare
Print a line each time any target (internal or external) is
prepared for building. scons prints this for each target it
considers, even if that target is up to date (see also
--debug=explain). This can help debug problems with targets
that aren't being built; it shows whether scons is at least
considering them or not.

presub
Print the raw command line used to build each target before the
construction environment variables are substituted. Also shows
which targets are being built by this command. Output looks
something like this:

$ scons --debug=presub
Building myprog.o with action(s):
$SHCC $SHCFLAGS $SHCCFLAGS $CPPFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES
...

stacktrace
Prints an internal Python stack trace when encountering an
otherwise unexplained error.

time
Prints various time profiling information:

• The time spent executing each individual build command

• The total build time (time SCons ran from beginning to end)

• The total time spent reading and executing SConscript files

• The total time SCons itself spent running (that is, not
counting reading and executing SConscript files)

• The total time spent executing all build commands

• The elapsed wall-clock time spent executing those build
commands

• The time spent processing each file passed to the
SConscript function

(When scons is executed without the -j option, the elapsed
wall-clock time will typically be slightly longer than the
total time spent executing all the build commands, due to the
SCons processing that takes place in between executing each
command. When scons is executed with the -j option, and your
build configuration allows good parallelization, the elapsed
wall-clock time should be significantly smaller than the total
time spent executing all the build commands, since multiple
build commands and intervening SCons processing should take
place in parallel.)

--diskcheck=type
Enable specific checks for whether or not there is a file on disk
where the SCons configuration expects a directory (or vice versa)
when searching for source and include files. type can be an
available diskcheck type or the special tokens all or none. A
comma-separated string can be used to select multiple checks. The
default setting is all.

Current available checks are:

match
to check that files and directories on disk match SCons'
expected configuration.

Disabling some or all of these checks can provide a performance
boost for large configurations, or when the configuration will
check for files and/or directories across networked or shared file
systems, at the slight increased risk of an incorrect build or of
not handling errors gracefully.

--duplicate=ORDER
There are three ways to duplicate files in a build tree: hard
links, soft (symbolic) links and copies. The default policy is to
prefer hard links to soft links to copies. You can specify a
different policy with this option. ORDER must be one of
hard-soft-copy (the default), soft-hard-copy, hard-copy, soft-copy
or copy. SCons will attempt to duplicate files using the
mechanisms in the specified order.

--enable-virtualenv
Import virtualenv-related variables to SCons.

--experimental=feature
Enable experimental features and/or tools. feature can be an
available feature name or the special tokens all or none. A
comma-separated string can be used to select multiple features. The
default setting is none.

Current available features are: ninja.

Caution
No Support offered for any features or tools enabled by this
flag.
Available since scons 4.2.

-f file, --file=file, --makefile=file, --sconstruct=file
Use file as the initial SConscript file. Multiple -f options may be
specified, in which case scons will read all of the specified
files.

-h, --help
Print a local help message for this project, if one is defined in
the SConscript files (see the Help function), plus a line that
refers to the standard SCons help message. If no local help message
is defined, prints the standard SCons help message (as for the -H
option) plus help for any local options defined through AddOption.
Exits after displaying the appropriate message.

Note that use of this option requires SCons to process the
SConscript files, so syntax errors may cause the help message not
to be displayed.

--hash-chunksize=KILOBYTES
Set the block size used when computing content signatures to
KILOBYTES. This value determines the size of the chunks which are
read in at once when computing signature hashes. Files below that
size are fully stored in memory before performing the signature
computation while bigger files are read in block-by-block. A huge
block-size leads to high memory consumption while a very small
block-size slows down the build considerably.

The default value is to use a chunk size of 64 kilobytes, which
should be appropriate for most uses.

Available since scons 4.2.

--hash-format=ALGORITHM
Set the hashing algorithm used by SCons to ALGORITHM. This value
determines the hashing algorithm used in generating content
signatures or CacheDir keys.

The supported list of values are: md5, sha1, and sha256. However,
the Python interpreter used to run SCons must have the
corresponding support available in the hashlib module to use the
specified algorithm.

Specifying this value changes the name of the SConsign database.
For example, --hash-format=sha256 will create a SConsign database
with name .sconsign_sha256.dblite.

If this option is not specified, a the first supported hash format
found is selected. Typically this is MD5, however, if you are on a
FIPS-compliant system and using a version of Python less than 3.9,
SHA1 or SHA256 will be chosen as the default. Python 3.9 and
onwards clients will always default to MD5, even in FIPS mode,
unless otherwise specified with the --hash-format option.

For MD5 databases (either explicitly specified with
--hash-format=md5 or defaulted), the SConsign database
is.sconsign.dblite. The newer SHA1 and SHA256 selections meanwhile
store their databases to .sconsign_algorithmname.dblite

Available since scons 4.2.

-H, --help-options
Print the standard help message about SCons command-line options
and exit.

-i, --ignore-errors
Ignore all errors from commands executed to rebuild files.

-I directory, --include-dir=directory
Specifies a directory to search for imported Python modules. If
several -I options are used, the directories are searched in the
order specified.

--ignore-virtualenv
Suppress importing virtualenv-related variables to SCons.

--implicit-cache
Cache implicit dependencies. This causes scons to use the implicit
(scanned) dependencies from the last time it was run instead of
scanning the files for implicit dependencies. This can
significantly speed up SCons, but with the following limitations:

scons will not detect changes to implicit dependency search paths
(e.g. $CPPPATH, $LIBPATH) that would ordinarily cause different
versions of same-named files to be used.

scons will miss changes in the implicit dependencies in cases where
a new implicit dependency is added earlier in the implicit
dependency search path (e.g. $CPPPATH, $LIBPATH) than a current
implicit dependency with the same name.

--implicit-deps-changed
Forces SCons to ignore the cached implicit dependencies. This
causes the implicit dependencies to be rescanned and recached. This
implies --implicit-cache.

--implicit-deps-unchanged
Force SCons to ignore changes in the implicit dependencies. This
causes cached implicit dependencies to always be used. This implies
--implicit-cache.

--install-sandbox=sandbox_path
When using the Install builders, prepend sandbox_path to the
installation paths such that all installed files will be placed
under that directory. This option is unavailable if one of Install,
InstallAs or InstallVersionedLib is not used in the SConscript
files.

--interactive
Starts SCons in interactive mode. The SConscript files are read
once and a scons>>> prompt is printed. Targets may now be rebuilt
by typing commands at interactive prompt without having to re-read
the SConscript files and re-initialize the dependency graph from
scratch.

SCons interactive mode supports the following commands:

build [OPTIONS] [TARGETS] ...
Builds the specified TARGETS (and their dependencies) with the
specified SCons command-line OPTIONS. b and scons are synonyms
for build.

The following SCons command-line options affect the build
command:

--cache-debug=FILE
--cache-disable, --no-cache
--cache-force, --cache-populate
--cache-readonly
--cache-show
--debug=TYPE
-i, --ignore-errors
-j N, --jobs=N
-k, --keep-going
-n, --no-exec, --just-print, --dry-run, --recon
-Q
-s, --silent, --quiet
--taskmastertrace=FILE
--tree=OPTIONS

Any other SCons command-line options that are specified do not
cause errors but have no effect on the build command (mainly
because they affect how the SConscript files are read, which
only happens once at the beginning of interactive mode).

clean [OPTIONS] [TARGETS] ...
Cleans the specified TARGETS (and their dependencies) with the
specified OPTIONS. c is a synonym. This command is itself a
synonym for build --clean

exit
Exits SCons interactive mode. You can also exit by terminating
input (Ctrl+D UNIX or Linux systems, (Ctrl+Z on Windows
systems).

help [COMMAND]
Provides a help message about the commands available in SCons
interactive mode. If COMMAND is specified, h and ? are
synonyms.

shell [COMMANDLINE]
Executes the specified COMMANDLINE in a subshell. If no
COMMANDLINE is specified, executes the interactive command
interpreter specified in the SHELL environment variable (on
UNIX and Linux systems) or the COMSPEC environment variable (on
Windows systems). sh and ! are synonyms.

version
Prints SCons version information.

An empty line repeats the last typed command. Command-line editing
can be used if the readline module is available.

$ scons --interactive
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons>>> build -n prog
scons>>> exit

-j N, --jobs=N
Specifies the maximum number of comcurrent jobs (commands) to run.
If there is more than one -j option, the last one is effective.

-k, --keep-going
Continue as much as possible after an error. The target that failed
and those that depend on it will not be remade, but other targets
specified on the command line will still be processed.

-m
Ignored for compatibility with non-GNU versions of Make.

--max-drift=SECONDS
Set the maximum expected drift in the modification time of files to
SECONDS. This value determines how long a file must be unmodified
before its cached content signature will be used instead of
calculating a new content signature (hash) of the file's contents.
The default value is 2 days, which means a file must have a
modification time of at least two days ago in order to have its
cached content signature used. A negative value means to never
cache the content signature and to ignore the cached value if there
already is one. A value of 0 means to always use the cached
signature, no matter how old the file is.

--md5-chunksize=KILOBYTES
A deprecated synonym for --hash-chunksize.

Deprecated since scons 4.2.

-n, --no-exec, --just-print, --dry-run, --recon
Set no execute mode. Print the commands that would be executed to
build any out-of-date target files, but do not execute the
commands.

The output is a best effort, as SCons cannot always precisely
determine what would be built. For example, if a file is generated
by a builder action that is later used in the build, that file is
not available to scan for dependencies on an unbuilt tree, or may
contain out of date information in a built tree.

Work which is done directly in Python code in SConscript files, as
opposed to work done by builder actions during the build phase,
will still be carried out. If it is important to avoid some such
work from taking place in no execute mode, it should be protected.
An SConscript file can determine which mode is active by querying
GetOption, as in the call if GetOption("no_exec"):

--no-site-dir
Prevents the automatic addition of the standard site_scons dirs to
sys.path. Also prevents loading the site_scons/site_init.py modules
if they exist, and prevents adding their site_scons/site_tools dirs
to the toolpath.

--package-type=type
The type or types of package to create when using the Package
builder. In the case of multiple types, type should be a
comma-separated string; SCons will try to build for all of those
packages. Note this option is only available if the packaging tool
has been enabled.

--profile=file
Run SCons under the Python profiler and save the results in the
specified file. The results may be analyzed using the Python pstats
module.

-q, --question
Do not run any commands, or print anything. Just return an exit
status that is zero if the specified targets are already up to
date, non-zero otherwise.

-Q
Quiets SCons status messages about reading SConscript files,
building targets and entering directories. Commands that are
executed to rebuild target files are still printed.

--random
Build dependencies in a random order. This is useful when building
multiple trees simultaneously with caching enabled, to prevent
multiple builds from simultaneously trying to build or retrieve the
same target files.

-s, --silent, --quiet
Silent. Do not print commands that are executed to rebuild target
files. Also suppresses SCons status messages.

-S, --no-keep-going, --stop
Ignored for compatibility with GNU Make

--site-dir=path
Use a specific path as the site directory rather than searching the
list of default site directories. This directory will be prepended
to sys.path, the module path/site_init.py will be loaded if it
exists, and path/site_tools will be added to the default toolpath.

The default set of site directories searched when --site-dir is not
specified depends on the system platform, as follows. Users or
system administrators can tune site-specific or project-specific
SCons behavior by setting up a site directory in one or more of
these locations. Directories are examined in the order given, from
most generic ("system" directories) to most specific (in the
current project), so the last-executed site_init.py file is the
most specific one, giving it the chance to override everything
else), and the directories are prepended to the paths, again so the
last directory examined comes first in the resulting path.

Windows:

%ALLUSERSPROFILE%/scons/site_scons
%LOCALAPPDATA%/scons/site_scons
%APPDATA%/scons/site_scons
%USERPROFILE%/.scons/site_scons
./site_scons

Note earlier versions of the documentation listed a different
path for the "system" site directory, this path is still
checked but its use is discouraged:

%ALLUSERSPROFILE%/Application Data/scons/site_scons

Mac OS X:

/Library/Application Support/SCons/site_scons
/opt/local/share/scons/site_scons (for MacPorts)
/sw/share/scons/site_scons (for Fink)
$HOME/Library/Application Support/SCons/site_scons
$HOME/.scons/site_scons
./site_scons

Solaris:

/opt/sfw/scons/site_scons
/usr/share/scons/site_scons
$HOME/.scons/site_scons
./site_scons

Linux, HPUX, and other Posix-like systems:

/usr/share/scons/site_scons
$HOME/.scons/site_scons
./site_scons

--stack-size=KILOBYTES
Set the size stack used to run threads to KILOBYTES. This value
determines the stack size of the threads used to run jobs. These
threads execute the actions of the builders for the nodes that are
out-of-date. This option has no effect unless the number of
concurrent build jobs is larger than one (as set by -j N or
--jobs=N on the command line or SetOption in a script).

Using a stack size that is too small may cause stack overflow
errors. This usually shows up as segmentation faults that cause
scons to abort before building anything. Using a stack size that is
too large will cause scons to use more memory than required and may
slow down the entire build process. The default value is to use a
stack size of 256 kilobytes, which should be appropriate for most
uses. You should not need to increase this value unless you
encounter stack overflow errors.

-t, --touch
Ignored for compatibility with GNU Make. (Touching a file to make
it appear up-to-date is unnecessary when using scons.)

--taskmastertrace=file
Prints trace information to the specified file about how the
internal Taskmaster object evaluates and controls the order in
which Nodes are built. A file name of - may be used to specify the
standard output.

--tree=type[,type...]
Prints a tree of the dependencies after each top-level target is
built. This prints out some or all of the tree, in various formats,
depending on the type specified:

all
Print the entire dependency tree after each top-level target is
built. This prints out the complete dependency tree, including
implicit dependencies and ignored dependencies.

derived
Restricts the tree output to only derived (target) files, not
source files.

linedraw
Draw the tree output using Unicode line-drawing characters
instead of plain ASCII text. This option acts as a modifier to
the selected type(s). If specified alone, without any type, it
behaves as if all had been specified.

Available since scons 4.0.

status
Prints status information for each displayed node.

prune
Prunes the tree to avoid repeating dependency information for
nodes that have already been displayed. Any node that has
already been displayed will have its name printed in [square
brackets], as an indication that the dependencies for that node
can be found by searching for the relevant output higher up in
the tree.

Multiple type choices may be specified, separated by commas:

# Prints only derived files, with status information:
scons --tree=derived,status

# Prints all dependencies of target, with status information
# and pruning dependencies of already-visited Nodes:
scons --tree=all,prune,status target

-u, --up, --search-up
Walks up the directory structure until an SConstruct, Sconstruct,
sconstruct, SConstruct.py, Sconstruct.py or sconstruct.py file is
found, and uses that as the top of the directory tree. If no
targets are specified on the command line, only targets at or below
the current directory will be built.

-U
Works exactly the same way as the -u option except for the way
default targets are handled. When this option is used and no
targets are specified on the command line, all default targets that
are defined in the SConscript(s) in the current directory are
built, regardless of what directory the resultant targets end up
in.

-v, --version
Print the scons version, copyright information, list of authors,
and any other relevant information. Then exit.

-w, --print-directory
Print a message containing the working directory before and after
other processing.

--no-print-directory
Turn off -w, even if it was turned on implicitly.

--warn=type, --warn=no-type
Enable or disable (with the prefix "no-") warnings (--warning is a
synonym). type specifies the type of warnings to be enabled or
disabled:

all
All warnings.

cache-version
Warnings about the derived-file cache directory specified by
CacheDir not using the latest configuration information. These
warnings are enabled by default.

cache-write-error
Warnings about errors trying to write a copy of a built file to
a specified derived-file cache specified by CacheDir. These
warnings are disabled by default.

corrupt-sconsign
Warnings about unfamiliar signature data in .sconsign files.
These warnings are enabled by default.

dependency
Warnings about dependencies. These warnings are disabled by
default.

deprecated
Warnings about use of currently deprecated features. These
warnings are enabled by default. Not all deprecation warnings
can be disabled with the --warn=no-deprecated option as some
deprecated features which are late in the deprecation cycle may
have been designated as mandatory warnings, and these will
still display. Warnings for certain deprecated features may
also be enabled or disabled individually; see below.

duplicate-environment
Warnings about attempts to specify a build of a target with two
different construction environments that use the same action.
These warnings are enabled by default.

fortran-cxx-mix
Warnings about linking Fortran and C++ object files in a single
executable, which can yield unpredictable behavior with some
compilers.

future-deprecated
Warnings about features that will be deprecated in the future.
Such warnings are disabled by default. Enabling future
deprecation warnings is recommended for projects that
redistribute SCons configurations for other users to build, so
that the project can be warned as soon as possible about
to-be-deprecated features that may require changes to the
configuration.

link
Warnings about link steps.

misleading-keywords
Warnings about the use of two commonly misspelled keywords
targets and sources to Builder calls. The correct spelling is
the singular form, even though target and source can themselves
refer to lists of names or nodes.

tool-qt-deprecated
Warnings about the qt tool being deprecated. These warnings are
disabled by default for the first phase of deprecation. Enable
to be reminded about use of this tool module. Available since
SCons 4.3.

missing-sconscript
Warnings about missing SConscript files. These warnings are
enabled by default.

no-object-count
Warnings about the --debug=object feature not working when
scons is run with the Python -O option or from optimized Python
(.pyo) modules.

no-parallel-support
Warnings about the version of Python not being able to support
parallel builds when the -j option is used. These warnings are
enabled by default.

python-version
Warnings about running SCons with a deprecated version of
Python. These warnings are enabled by default.

reserved-variable
Warnings about attempts to set the reserved construction
variable names $CHANGED_SOURCES, $CHANGED_TARGETS, $TARGET,
$TARGETS, $SOURCE, $SOURCES, $UNCHANGED_SOURCES or
$UNCHANGED_TARGETS. These warnings are disabled by default.

stack-size
Warnings about requests to set the stack size that could not be
honored. These warnings are enabled by default.

target_not_build
Warnings about a build rule not building the expected targets.
These warnings are disabled by default.

-Y repository, --repository=repository, --srcdir=repository
Search the specified repository for any input and target files not
found in the local directory hierarchy. Multiple -Y options may be
specified, in which case the repositories are searched in the order
specified.

SCONSCRIPT FILE REFERENCE
SConscript Files
The build configuration is described by one or more files, known as
SConscript files. There must be at least one file for a valid build
(scons will quit if it does not find one). scons by default looks for
this file by the name SConstruct in the directory from which you run
scons, though if necessary, also looks for alternative file names
Sconstruct, sconstruct, SConstruct.py, Sconstruct.py and sconstruct.py
in that order. A different file name (which can include a pathname
part) may be specified via the -f option. Except for the SConstruct
file, these files are not searched for automatically; you add
additional configuration files to the build by calling the SConscript
function. This allows parts of the build to be conditionally included
or excluded at run-time depending on how scons is invoked.

Each SConscript file in a build configuration is invoked independently
in a separate context. This provides necessary isolation so that
different parts of the build don't accidentally step on each other. You
have to be explicit about sharing information, by using the Export
function or the exports argument to the SConscript function, as well as
the Return function in a called SConscript file, and comsume shared
information by using the Import function.

The following sections describe the various SCons facilities that can
be used in SConscript files. Quick links:
Construction Environments
Tools
Builder Methods
Methods and Functions to do Things
SConscript Variables
Construction Variables
Configure Contexts
Command-Line Construction Variables
Node Objects

Construction Environments
A Construction Environment is the basic means by which you communicate
build information to SCons. A new construction environment is created
using the Environment function:

env = Environment()

Construction environment attributes called Construction Variables may
be set either by specifying them as keyword arguments when the object
is created or by assigning them a value after the object is created.
These two are nominally equivalent:

env = Environment(FOO='foo')
env['FOO'] = 'foo'

Note that certain settings which affect tool detection are referenced
only when the tools are initializided, so you either need either to
supply them as part of the call to Environment, or defer tool
initialization. For example, initializing the Microsoft Visual C++
version you wish to use:

# initializes msvc to v14.1
env = Environment(MSVC_VERSION="14.1")

env = Environment()
# msvc tool was initialized to default, does not reinitialize
env['MSVC_VERSION'] = "14.1"

env = Environment(tools=[])
env['MSVC_VERSION'] = "14.1"
# msvc tool initialization was deferred, so will pick up new value
env.Tool('default')

As a convenience, construction variables may also be set or modified by
the parse_flags keyword argument during object creation, which has the
effect of the env.MergeFlags method being applied to the argument value
after all other processing is completed. This is useful either if the
exact content of the flags is unknown (for example, read from a control
file) or if the flags need to be distributed to a number of
construction variables. env.ParseFlags describes how these arguments
are distributed to construction variables.

env = Environment(parse_flags='-Iinclude -DEBUG -lm')

This example adds 'include' to the $CPPPATH construction variable,
'EBUG' to $CPPDEFINES, and 'm' to $LIBS.

An existing construction environment can be duplicated by calling the
env.Clone method. Without arguments, it will be a copy with the same
settings. Otherwise, env.Clone takes the same arguments as Environment,
and uses the arguments to create a modified copy.

SCons provides a special construction environment called the Default
Environment. The default environment is used only for global functions,
that is, construction activities called without the context of a
regular construction environment. See DefaultEnvironment for more
information.

By default, a new construction environment is initialized with a set of
builder methods and construction variables that are appropriate for the
current platform. The optional platform keyword argument may be used to
specify that the construction environment should be initialized for a
different platform:

env = Environment(platform='cygwin')

Specifying a platform initializes the appropriate construction
variables in the environment to use and generate file names with
prefixes and suffixes appropriate for that platform.

Note that the win32 platform adds the SystemDrive and SystemRoot
variables from the user's external environment to the construction
environment's ENV dictionary. This is so that any executed commands
that use sockets to connect with other systems will work on Windows
systems.

The platform argument may be a string value representing one of the
pre-defined platforms (aix, cygwin, darwin, hpux, irix, os2, posix,
sunos or win32), or it may be be a callable platform object returned by
a call to Platform selecting a pre-defined platform, or it may be a
user-supplied callable, in which case the Environment method will call
it to update the new construction environment:

def my_platform(env):
env['VAR'] = 'xyzzy'

env = Environment(platform=my_platform)

Note that supplying a non-default platform or custom fuction for
initialization may bypass settings that should happen for the host
system and should be used with care. It is most useful in the case
where the platform is an alternative for the one that would be
auto-detected, such as platform="cygwin" on a system which would
otherwise identify as win32.

The optional tools and toolpath keyword arguments affect the way tools
available to the environment are initialized. See the section called
“Tools” for details.

The optional variables keyword argument allows passing a Variables
object which will be used in the initialization of the construction
environment See the section called “Command-Line Construction
Variables” for details.

Tools
SCons has a large number of predefined tool modules (more properly,
tool specification modules) which are used to help initialize the
construction environment. An SCons tool is only responsible for setup.
For example, if an SConscript file declares the need to construct an
object file from a C-language source file by calling the Object
builder, then a tool representing an available C compiler needs to have
run first, to set up that builder and all the construction variables it
needs in the associated construction environment; the tool itself is
not called in the process of the build. Normally this happens invisibly
as scons has per-platform lists of default tools, and it steps through
those tools, calling the ones which are actually applicable, skipping
those where necessary programs are not installed on the build system,
or other preconditions are not met.

A specific set of tools with which to initialize an environment when
creating it may be specified using the optional keyword argument tools,
which takes a list of tool names. This is useful to override the
defaults, to specify non-default built-in tools, and to supply added
tools:

env = Environment(tools=['msvc', 'lex'])

Tools can also be directly called by using the Tool method (see below).

The tools argument overrides the default tool list, it does not add to
it, so be sure to include all the tools you need. For example if you
are building a c/c++ program you must specify a tool for at least a
compiler and a linker, as in tools=['clang', 'link']. The tool name
'default' can be used to retain the default list.

If no tools argument is specified, or if tools includes 'default', then
scons will auto-detect usable tools, using the execution environment
value of PATH (that is, env['ENV']['PATH'] - the external evironment
PATH from os.environ is not used) for looking up any backing programs,
and the platform name in effect to determine the default tools for that
platform. Changing the PATH variable after the construction environment
is constructed will not cause the tools to be re-detected.

Additional tools can be added, see the Extending SCons section and
specifically Tool Modules.

SCons supports the following tool specifications out of the box:

386asm
Sets construction variables for the 386ASM assembler for the Phar
Lap ETS embedded operating system.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

aixc++
Sets construction variables for the IMB xlc / Visual Age C++
compiler.

Sets: $CXX, $CXXVERSION, $SHCXX, $SHOBJSUFFIX.

aixcc
Sets construction variables for the IBM xlc / Visual Age C
compiler.

Sets: $CC, $CCVERSION, $SHCC.

aixf77
Sets construction variables for the IBM Visual Age f77 Fortran
compiler.

Sets: $F77, $SHF77.

aixlink
Sets construction variables for the IBM Visual Age linker.

Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

applelink
Sets construction variables for the Apple linker (similar to the
GNU linker).

Sets: $APPLELINK_COMPATIBILITY_VERSION, $APPLELINK_CURRENT_VERSION,
$APPLELINK_NO_COMPATIBILITY_VERSION, $APPLELINK_NO_CURRENT_VERSION,
$FRAMEWORKPATHPREFIX, $LDMODULECOM, $LDMODULEFLAGS,
$LDMODULEPREFIX, $LDMODULESUFFIX, $LINKCOM, $SHLINKCOM,
$SHLINKFLAGS, $_APPLELINK_COMPATIBILITY_VERSION,
$_APPLELINK_CURRENT_VERSION, $_FRAMEWORKPATH, $_FRAMEWORKS.

Uses: $FRAMEWORKSFLAGS.

ar
Sets construction variables for the ar library archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $RANLIB,
$RANLIBCOM, $RANLIBFLAGS.

as
Sets construction variables for the as assembler.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

bcc32
Sets construction variables for the bcc32 compiler.

Sets: $CC, $CCCOM, $CCFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX,
$CPPDEFSUFFIX, $INCPREFIX, $INCSUFFIX, $SHCC, $SHCCCOM, $SHCCFLAGS,
$SHCFLAGS, $SHOBJSUFFIX.

Uses: $_CPPDEFFLAGS, $_CPPINCFLAGS.

cc
Sets construction variables for generic POSIX C compilers.

Sets: $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CFILESUFFIX, $CFLAGS,
$CPPDEFPREFIX, $CPPDEFSUFFIX, $FRAMEWORKPATH, $FRAMEWORKS,
$INCPREFIX, $INCSUFFIX, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS,
$SHOBJSUFFIX.

Uses: $CCCOMSTR, $PLATFORM, $SHCCCOMSTR.

clang
Set construction variables for the Clang C compiler.

Sets: $CC, $CCDEPFLAGS, $CCVERSION, $SHCCFLAGS.

clangxx
Set construction variables for the Clang C++ compiler.

Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX,
$STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME.

compilation_db
Sets up CompilationDatabase builder which generates a clang tooling
compatible compilation database.

Sets: $COMPILATIONDB_COMSTR, $COMPILATIONDB_PATH_FILTER,
$COMPILATIONDB_USE_ABSPATH.

cvf
Sets construction variables for the Compaq Visual Fortran compiler.

Sets: $FORTRAN, $FORTRANCOM, $FORTRANMODDIR, $FORTRANMODDIRPREFIX,
$FORTRANMODDIRSUFFIX, $FORTRANPPCOM, $OBJSUFFIX, $SHFORTRANCOM,
$SHFORTRANPPCOM.

Uses: $CPPFLAGS, $FORTRANFLAGS, $SHFORTRANFLAGS, $_CPPDEFFLAGS,
$_FORTRANINCFLAGS, $_FORTRANMODFLAG.

cXX
Sets construction variables for generic POSIX C++ compilers.

Sets: $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM, $CXXFILESUFFIX,
$CXXFLAGS, $INCPREFIX, $INCSUFFIX, $OBJSUFFIX, $SHCXX, $SHCXXCOM,
$SHCXXFLAGS, $SHOBJSUFFIX.

Uses: $CXXCOMSTR, $SHCXXCOMSTR.

cyglink
Set construction variables for cygwin linker/loader.

Sets: $IMPLIBPREFIX, $IMPLIBSUFFIX, $LDMODULEVERSIONFLAGS,
$LINKFLAGS, $RPATHPREFIX, $RPATHSUFFIX, $SHLIBPREFIX, $SHLIBSUFFIX,
$SHLIBVERSIONFLAGS, $SHLINKCOM, $SHLINKFLAGS,
$_LDMODULEVERSIONFLAGS, $_SHLIBVERSIONFLAGS.

default
Sets construction variables for a default list of Tool modules. Use
default in the tools list to retain the original defaults, since
the tools parameter is treated as a literal statement of the tools
to be made available in that construction environment, not an
addition.

The list of tools selected by default is not static, but is
dependent both on the platform and on the software installed on the
platform. Some tools will not initialize if an underlying command
is not found, and some tools are selected from a list of choices on
a first-found basis. The finished tool list can be examined by
inspecting the $TOOLS construction variable in the construction
environment.

On all platforms, the tools from the following list are selected if
their respective conditions are met: filesystem;, wix, lex, yacc,
rpcgen, swig, jar, javac, javah, rmic, dvipdf, dvips, gs, tex,
latex, pdflatex, pdftex, tar, zip, textfile.

On Linux systems, the default tools list selects (first-found): a C
compiler from gcc, intelc, icc, cc; a C++ compiler from g++,
intelc, icc, cXX; an assembler from gas, nasm, masm; a linker from
gnulink, ilink; a Fortran compiler from gfortran, g77, ifort, ifl,
f95, f90, f77; and a static archiver ar. It also selects all found
from the list m4 rpm.

On Windows systems, the default tools list selects (first-found): a
C compiler from msvc, mingw, gcc, intelc, icl, icc, cc, bcc32; a
C++ compiler from msvc, intelc, icc, g++, cXX, bcc32; an assembler
from masm, nasm, gas, 386asm; a linker from mslink, gnulink, ilink,
linkloc, ilink32; a Fortran compiler from gfortran, g77, ifl, cvf,
f95, f90, fortran; and a static archiver from mslib, ar, tlib; It
also selects all found from the list msvs, midl.

On MacOS systems, the default tools list selects (first-found): a C
compiler from gcc, cc; a C++ compiler from g++, cXX; an assembler
as; a linker from applelink, gnulink; a Fortran compiler from
gfortran, f95, f90, g77; and a static archiver ar. It also selects
all found from the list m4, rpm.

Default lists for other platforms can be found by examining the
scons source code (see SCons/Tool/__init__.py).

dmd
Sets construction variables for D language compiler DMD.

Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
$DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
$DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX,
$DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX, $DLIBLINKSUFFIX,
$DLINK, $DLINKCOM, $DLINKFLAGPREFIX, $DLINKFLAGS, $DLINKFLAGSUFFIX,
$DPATH, $DRPATHPREFIX, $DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS,
$DVERSUFFIX, $SHDC, $SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK,
$SHDLINKCOM, $SHDLINKFLAGS.

docbook
This tool tries to make working with Docbook in SCons a little
easier. It provides several toolchains for creating different
output formats, like HTML or PDF. Contained in the package is a
distribution of the Docbook XSL stylesheets as of version 1.76.1.
As long as you don't specify your own stylesheets for
customization, these official versions are picked as
default...which should reduce the inevitable setup hassles for you.

Implicit dependencies to images and XIncludes are detected
automatically if you meet the HTML requirements. The additional
stylesheet utils/xmldepend.xsl by Paul DuBois is used for this
purpose.

Note, that there is no support for XML catalog resolving offered!
This tool calls the XSLT processors and PDF renderers with the
stylesheets you specified, that's it. The rest lies in your hands
and you still have to know what you're doing when resolving names
via a catalog.

For activating the tool "docbook", you have to add its name to the
Environment constructor, like this

env = Environment(tools=['docbook'])

On its startup, the docbook tool tries to find a required xsltproc
processor, and a PDF renderer, e.g. fop. So make sure that these
are added to your system's environment PATH and can be called
directly without specifying their full path.

For the most basic processing of Docbook to HTML, you need to have
installed

• the Python lxml binding to libxml2, or

• a standalone XSLT processor, currently detected are xsltproc,
saxon, saxon-xslt and xalan.

Rendering to PDF requires you to have one of the applications fop
or xep installed.

Creating a HTML or PDF document is very simple and straightforward.
Say

env = Environment(tools=['docbook'])
env.DocbookHtml('manual.html', 'manual.xml')
env.DocbookPdf('manual.pdf', 'manual.xml')

to get both outputs from your XML source manual.xml. As a shortcut,
you can give the stem of the filenames alone, like this:

env = Environment(tools=['docbook'])
env.DocbookHtml('manual')
env.DocbookPdf('manual')

and get the same result. Target and source lists are also
supported:

env = Environment(tools=['docbook'])
env.DocbookHtml(['manual.html','reference.html'], ['manual.xml','reference.xml'])

or even

env = Environment(tools=['docbook'])
env.DocbookHtml(['manual','reference'])

Important
Whenever you leave out the list of sources, you may not specify
a file extension! The Tool uses the given names as file stems,
and adds the suffixes for target and source files accordingly.
The rules given above are valid for the Builders DocbookHtml,
DocbookPdf, DocbookEpub, DocbookSlidesPdf and DocbookXInclude. For
the DocbookMan transformation you can specify a target name, but
the actual output names are automatically set from the refname
entries in your XML source.

The Builders DocbookHtmlChunked, DocbookHtmlhelp and
DocbookSlidesHtml are special, in that:

1. they create a large set of files, where the exact names and
their number depend on the content of the source file, and

2. the main target is always named index.html, i.e. the output
name for the XSL transformation is not picked up by the
stylesheets.

As a result, there is simply no use in specifying a target HTML
name. So the basic syntax for these builders is always:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('manual')

If you want to use a specific XSL file, you can set the additional
xsl parameter to your Builder call as follows:

env.DocbookHtml('other.html', 'manual.xml', xsl='html.xsl')

Since this may get tedious if you always use the same local naming
for your customized XSL files, e.g. html.xsl for HTML and pdf.xsl
for PDF output, a set of variables for setting the default XSL name
is provided. These are:

DOCBOOK_DEFAULT_XSL_HTML
DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
DOCBOOK_DEFAULT_XSL_HTMLHELP
DOCBOOK_DEFAULT_XSL_PDF
DOCBOOK_DEFAULT_XSL_EPUB
DOCBOOK_DEFAULT_XSL_MAN
DOCBOOK_DEFAULT_XSL_SLIDESPDF
DOCBOOK_DEFAULT_XSL_SLIDESHTML

and you can set them when constructing your environment:

env = Environment(
tools=['docbook'],
DOCBOOK_DEFAULT_XSL_HTML='html.xsl',
DOCBOOK_DEFAULT_XSL_PDF='pdf.xsl',
)
env.DocbookHtml('manual') # now uses html.xsl

Sets: $DOCBOOK_DEFAULT_XSL_EPUB, $DOCBOOK_DEFAULT_XSL_HTML,
$DOCBOOK_DEFAULT_XSL_HTMLCHUNKED, $DOCBOOK_DEFAULT_XSL_HTMLHELP,
$DOCBOOK_DEFAULT_XSL_MAN, $DOCBOOK_DEFAULT_XSL_PDF,
$DOCBOOK_DEFAULT_XSL_SLIDESHTML, $DOCBOOK_DEFAULT_XSL_SLIDESPDF,
$DOCBOOK_FOP, $DOCBOOK_FOPCOM, $DOCBOOK_FOPFLAGS, $DOCBOOK_XMLLINT,
$DOCBOOK_XMLLINTCOM, $DOCBOOK_XMLLINTFLAGS, $DOCBOOK_XSLTPROC,
$DOCBOOK_XSLTPROCCOM, $DOCBOOK_XSLTPROCFLAGS,
$DOCBOOK_XSLTPROCPARAMS.

Uses: $DOCBOOK_FOPCOMSTR, $DOCBOOK_XMLLINTCOMSTR,
$DOCBOOK_XSLTPROCCOMSTR.

dvi
Attaches the DVI builder to the construction environment.

dvipdf
Sets construction variables for the dvipdf utility.

Sets: $DVIPDF, $DVIPDFCOM, $DVIPDFFLAGS.

Uses: $DVIPDFCOMSTR.

dvips
Sets construction variables for the dvips utility.

Sets: $DVIPS, $DVIPSFLAGS, $PSCOM, $PSPREFIX, $PSSUFFIX.

Uses: $PSCOMSTR.

f03
Set construction variables for generic POSIX Fortran 03 compilers.

Sets: $F03, $F03COM, $F03FLAGS, $F03PPCOM, $SHF03, $SHF03COM,
$SHF03FLAGS, $SHF03PPCOM, $_F03INCFLAGS.

Uses: $F03COMSTR, $F03PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF03COMSTR,
$SHF03PPCOMSTR.

f08
Set construction variables for generic POSIX Fortran 08 compilers.

Sets: $F08, $F08COM, $F08FLAGS, $F08PPCOM, $SHF08, $SHF08COM,
$SHF08FLAGS, $SHF08PPCOM, $_F08INCFLAGS.

Uses: $F08COMSTR, $F08PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF08COMSTR,
$SHF08PPCOMSTR.

f77
Set construction variables for generic POSIX Fortran 77 compilers.

Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77FLAGS, $F77PPCOM,
$F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHF77,
$SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM,
$SHFORTRANFLAGS, $SHFORTRANPPCOM, $_F77INCFLAGS.

Uses: $F77COMSTR, $F77PPCOMSTR, $FORTRANCOMMONFLAGS,
$FORTRANCOMSTR, $FORTRANFLAGS, $FORTRANPPCOMSTR, $SHF77COMSTR,
$SHF77PPCOMSTR, $SHFORTRANCOMSTR, $SHFORTRANFLAGS,
$SHFORTRANPPCOMSTR.

f90
Set construction variables for generic POSIX Fortran 90 compilers.

Sets: $F90, $F90COM, $F90FLAGS, $F90PPCOM, $SHF90, $SHF90COM,
$SHF90FLAGS, $SHF90PPCOM, $_F90INCFLAGS.

Uses: $F90COMSTR, $F90PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF90COMSTR,
$SHF90PPCOMSTR.

f95
Set construction variables for generic POSIX Fortran 95 compilers.

Sets: $F95, $F95COM, $F95FLAGS, $F95PPCOM, $SHF95, $SHF95COM,
$SHF95FLAGS, $SHF95PPCOM, $_F95INCFLAGS.

Uses: $F95COMSTR, $F95PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF95COMSTR,
$SHF95PPCOMSTR.

fortran
Set construction variables for generic POSIX Fortran compilers.

Sets: $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHFORTRAN,
$SHFORTRANCOM, $SHFORTRANFLAGS, $SHFORTRANPPCOM.

Uses: $CPPFLAGS, $FORTRANCOMSTR, $FORTRANPPCOMSTR,
$SHFORTRANCOMSTR, $SHFORTRANPPCOMSTR, $_CPPDEFFLAGS.

g++
Set construction variables for the g++ C++ compiler.

Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX.

g77
Set construction variables for the g77 Fortran compiler.

Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77PPCOM,
$F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHF77,
$SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM,
$SHFORTRANFLAGS, $SHFORTRANPPCOM.

Uses: $F77FLAGS, $FORTRANCOMMONFLAGS, $FORTRANFLAGS.

gas
Sets construction variables for the gas assembler. Calls the as
tool.

Sets: $AS.

gcc
Set construction variables for the gcc C compiler.

Sets: $CC, $CCDEPFLAGS, $CCVERSION, $SHCCFLAGS.

gdc
Sets construction variables for the D language compiler GDC.

gettext
This is actually a toolset, which supports internationalization and
localization of software being constructed with SCons. The toolset
loads following tools:

• xgettext - to extract internationalized messages from source
code to POT file(s),

• msginit - may be optionally used to initialize PO files,

• msgmerge - to update PO files, that already contain translated
messages,

• msgfmt - to compile textual PO file to binary installable MO
file.

When you enable gettext, it internally loads all abovementioned
tools, so you're encouraged to see their individual documentation.

Each of the above tools provides its own builder(s) which may be
used to perform particular activities related to software
internationalization. You may be however interested in top-level
Translate builder.

To use gettext tools add 'gettext' tool to your environment:

env = Environment( tools = ['default', 'gettext'] )

gfortran
Sets construction variables for the GNU Fortran compiler. Calls the
fortran Tool module to set variables.

Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90,
$SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

gnulink
Set construction variables for GNU linker/loader.

Sets: $LDMODULEVERSIONFLAGS, $RPATHPREFIX, $RPATHSUFFIX,
$SHLIBVERSIONFLAGS, $SHLINKFLAGS, $_LDMODULESONAME, $_SHLIBSONAME.

gs
This Tool sets the required construction variables for working with
the Ghostscript software. It also registers an appropriate Action
with the PDF Builder, such that the conversion from PS/EPS to PDF
happens automatically for the TeX/LaTeX toolchain. Finally, it adds
an explicit Gs Builder for Ghostscript to the environment.

Sets: $GS, $GSCOM, $GSFLAGS.

Uses: $GSCOMSTR.

hpc++
Set construction variables for the compilers aCC on HP/UX systems.

hpcc
Set construction variables for aCC compilers on HP/UX systems.
Calls the cXX tool for additional variables.

Sets: $CXX, $CXXVERSION, $SHCXXFLAGS.

hplink
Sets construction variables for the linker on HP/UX systems.

Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

icc
Sets construction variables for the icc compiler on OS/2 systems.

Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX,
$CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX.

Uses: $CCFLAGS, $CFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

icl
Sets construction variables for the Intel C/C++ compiler. Calls the
intelc Tool module to set its variables.

ifl
Sets construction variables for the Intel Fortran compiler.

Sets: $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHFORTRANCOM,
$SHFORTRANPPCOM.

Uses: $CPPFLAGS, $FORTRANFLAGS, $_CPPDEFFLAGS, $_FORTRANINCFLAGS.

ifort
Sets construction variables for newer versions of the Intel Fortran
compiler for Linux.

Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90,
$SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

ilink
Sets construction variables for the ilink linker on OS/2 systems.

Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX,
$LINK, $LINKCOM, $LINKFLAGS.

ilink32
Sets construction variables for the Borland ilink32 linker.

Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX,
$LINK, $LINKCOM, $LINKFLAGS.

install
Sets construction variables for file and directory installation.

Sets: $INSTALL, $INSTALLSTR.

intelc
Sets construction variables for the Intel C/C++ compiler (Linux and
Windows, version 7 and later). Calls the gcc or msvc (on Linux and
Windows, respectively) tool to set underlying variables.

Sets: $AR, $CC, $CXX, $INTEL_C_COMPILER_VERSION, $LINK.

jar
Sets construction variables for the jar utility.

Sets: $JAR, $JARCOM, $JARFLAGS, $JARSUFFIX.

Uses: $JARCOMSTR.

javac
Sets construction variables for the javac compiler.

Sets: $JAVABOOTCLASSPATH, $JAVAC, $JAVACCOM, $JAVACFLAGS,
$JAVACLASSPATH, $JAVACLASSSUFFIX, $JAVAINCLUDES, $JAVASOURCEPATH,
$JAVASUFFIX.

Uses: $JAVACCOMSTR.

javah
Sets construction variables for the javah tool.

Sets: $JAVACLASSSUFFIX, $JAVAH, $JAVAHCOM, $JAVAHFLAGS.

Uses: $JAVACLASSPATH, $JAVAHCOMSTR.

latex
Sets construction variables for the latex utility.

Sets: $LATEX, $LATEXCOM, $LATEXFLAGS.

Uses: $LATEXCOMSTR.

ldc
Sets construction variables for the D language compiler LDC2.

lex
Sets construction variables for the lex lexical analyser.

Sets: $LEX, $LEXCOM, $LEXFLAGS, $LEXUNISTD.

Uses: $LEXCOMSTR, $LEXFLAGS, $LEX_HEADER_FILE, $LEX_TABLES_FILE.

link
Sets construction variables for generic POSIX linkers. This is a
"smart" linker tool which selects a compiler to complete the
linking based on the types of source files.

Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS,
$LDMODULENOVERSIONSYMLINKS, $LDMODULEPREFIX, $LDMODULESUFFIX,
$LDMODULEVERSION, $LDMODULEVERSIONFLAGS, $LIBDIRPREFIX,
$LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM,
$LINKFLAGS, $SHLIBSUFFIX, $SHLINK, $SHLINKCOM, $SHLINKFLAGS,
$__LDMODULEVERSIONFLAGS, $__SHLIBVERSIONFLAGS.

Uses: $LDMODULECOMSTR, $LINKCOMSTR, $SHLINKCOMSTR.

linkloc
Sets construction variables for the LinkLoc linker for the Phar Lap
ETS embedded operating system.

Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX,
$LINK, $LINKCOM, $LINKFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS.

Uses: $LINKCOMSTR, $SHLINKCOMSTR.

m4
Sets construction variables for the m4 macro processor.

Sets: $M4, $M4COM, $M4FLAGS.

Uses: $M4COMSTR.

masm
Sets construction variables for the Microsoft assembler.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $ASCOMSTR, $ASPPCOMSTR, $CPPFLAGS, $_CPPDEFFLAGS,
$_CPPINCFLAGS.

midl
Sets construction variables for the Microsoft IDL compiler.

Sets: $MIDL, $MIDLCOM, $MIDLFLAGS.

Uses: $MIDLCOMSTR.

mingw
Sets construction variables for MinGW (Minimal Gnu on Windows).

Sets: $AS, $CC, $CXX, $LDMODULECOM, $LIBPREFIX, $LIBSUFFIX,
$OBJSUFFIX, $RC, $RCCOM, $RCFLAGS, $RCINCFLAGS, $RCINCPREFIX,
$RCINCSUFFIX, $SHCCFLAGS, $SHCXXFLAGS, $SHLINKCOM, $SHLINKFLAGS,
$SHOBJSUFFIX, $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX.

Uses: $RCCOMSTR, $SHLINKCOMSTR.

msgfmt
This scons tool is a part of scons gettext toolset. It provides
scons interface to msgfmt(1) command, which generates binary
message catalog (MO) from a textual translation description (PO).

Sets: $MOSUFFIX, $MSGFMT, $MSGFMTCOM, $MSGFMTCOMSTR, $MSGFMTFLAGS,
$POSUFFIX.

Uses: $LINGUAS_FILE.

msginit
This scons tool is a part of scons gettext toolset. It provides
scons interface to msginit(1) program, which creates new PO file,
initializing the meta information with values from user's
environment (or options).

Sets: $MSGINIT, $MSGINITCOM, $MSGINITCOMSTR, $MSGINITFLAGS,
$POAUTOINIT, $POCREATE_ALIAS, $POSUFFIX, $POTSUFFIX,
$_MSGINITLOCALE.

Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

msgmerge
This scons tool is a part of scons gettext toolset. It provides
scons interface to msgmerge(1) command, which merges two Uniform
style .po files together.

Sets: $MSGMERGE, $MSGMERGECOM, $MSGMERGECOMSTR, $MSGMERGEFLAGS,
$POSUFFIX, $POTSUFFIX, $POUPDATE_ALIAS.

Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

mslib
Sets construction variables for the Microsoft mslib library
archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

Uses: $ARCOMSTR.

mslink
Sets construction variables for the Microsoft linker.

Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS, $LDMODULEPREFIX,
$LDMODULESUFFIX, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $REGSVR, $REGSVRCOM,
$REGSVRFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS, $WINDOWSDEFPREFIX,
$WINDOWSDEFSUFFIX, $WINDOWSEXPPREFIX, $WINDOWSEXPSUFFIX,
$WINDOWSPROGMANIFESTPREFIX, $WINDOWSPROGMANIFESTSUFFIX,
$WINDOWSSHLIBMANIFESTPREFIX, $WINDOWSSHLIBMANIFESTSUFFIX,
$WINDOWS_INSERT_DEF.

Uses: $LDMODULECOMSTR, $LINKCOMSTR, $REGSVRCOMSTR, $SHLINKCOMSTR.

mssdk
Sets variables for Microsoft Platform SDK and/or Windows SDK. Note
that unlike most other Tool modules, mssdk does not set
construction variables, but sets the environment variables in the
environment SCons uses to execute the Microsoft toolchain:
%INCLUDE%, %LIB%, %LIBPATH% and %PATH%.

Uses: $MSSDK_DIR, $MSSDK_VERSION, $MSVS_VERSION.

msvc
Sets construction variables for the Microsoft Visual C/C++
compiler.

Sets: $BUILDERS, $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CCPCHFLAGS,
$CCPDBFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX, $CPPDEFSUFFIX,
$CXX, $CXXCOM, $CXXFILESUFFIX, $CXXFLAGS, $INCPREFIX, $INCSUFFIX,
$OBJPREFIX, $OBJSUFFIX, $PCHCOM, $PCHPDBFLAGS, $RC, $RCCOM,
$RCFLAGS, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHCXX,
$SHCXXCOM, $SHCXXFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

Uses: $CCCOMSTR, $CXXCOMSTR, $MSVC_NOTFOUND_POLICY, $PCH, $PCHSTOP,
$PDB, $SHCCCOMSTR, $SHCXXCOMSTR.

msvs
Sets construction variables for Microsoft Visual Studio.

Sets: $MSVSBUILDCOM, $MSVSCLEANCOM, $MSVSENCODING, $MSVSPROJECTCOM,
$MSVSREBUILDCOM, $MSVSSCONS, $MSVSSCONSCOM, $MSVSSCONSCRIPT,
$MSVSSCONSFLAGS, $MSVSSOLUTIONCOM.

mwcc
Sets construction variables for the Metrowerks CodeWarrior
compiler.

Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX,
$CXX, $CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX,
$MWCW_VERSION, $MWCW_VERSIONS, $SHCC, $SHCCCOM, $SHCCFLAGS,
$SHCFLAGS, $SHCXX, $SHCXXCOM, $SHCXXFLAGS.

Uses: $CCCOMSTR, $CXXCOMSTR, $SHCCCOMSTR, $SHCXXCOMSTR.

mwld
Sets construction variables for the Metrowerks CodeWarrior linker.

Sets: $AR, $ARCOM, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
$LIBLINKSUFFIX, $LINK, $LINKCOM, $SHLINK, $SHLINKCOM, $SHLINKFLAGS.

nasm
Sets construction variables for the nasm Netwide Assembler.

Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

Uses: $ASCOMSTR, $ASPPCOMSTR.

ninja
Sets up the Ninja builder, which generates a ninja build file, and
then optionally runs ninja.

Note
This is an experimental feature. This functionality is subject
to change and/or removal without a deprecation cycle.
Sets: $IMPLICIT_COMMAND_DEPENDENCIES, $NINJA_ALIAS_NAME,
$NINJA_CMD_ARGS, $NINJA_COMPDB_EXPAND, $NINJA_DEPFILE_PARSE_FORMAT,
$NINJA_DIR, $NINJA_DISABLE_AUTO_RUN, $NINJA_ENV_VAR_CACHE,
$NINJA_FILE_NAME, $NINJA_FORCE_SCONS_BUILD,
$NINJA_GENERATED_SOURCE_ALIAS_NAME,
$NINJA_GENERATED_SOURCE_SUFFIXES, $NINJA_MSVC_DEPS_PREFIX,
$NINJA_POOL, $NINJA_REGENERATE_DEPS,
$NINJA_SCONS_DAEMON_KEEP_ALIVE, $NINJA_SCONS_DAEMON_PORT,
$NINJA_SYNTAX, $_NINJA_REGENERATE_DEPS_FUNC.

Uses: $AR, $ARCOM, $ARFLAGS, $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS,
$CXX, $CXXCOM, $ESCAPE, $LINK, $LINKCOM, $PLATFORM,
$PRINT_CMD_LINE_FUNC, $PROGSUFFIX, $RANLIB, $RANLIBCOM, $SHCCCOM,
$SHCXXCOM, $SHLINK, $SHLINKCOM.

packaging
Sets construction variables for the Package Builder. If this tool
is enabled, the --package-type command-line option is also enabled.

pdf
Sets construction variables for the Portable Document Format
builder.

Sets: $PDFPREFIX, $PDFSUFFIX.

pdflatex
Sets construction variables for the pdflatex utility.

Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS.

Uses: $PDFLATEXCOMSTR.

pdftex
Sets construction variables for the pdftex utility.

Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS,
$PDFTEX, $PDFTEXCOM, $PDFTEXFLAGS.

Uses: $PDFLATEXCOMSTR, $PDFTEXCOMSTR.

python
Loads the Python source scanner into the invoking environment. When
loaded, the scanner will attempt to find implicit dependencies for
any Python source files in the list of sources provided to an
Action that uses this environment.

Available since scons 4.0..

qt
Sets construction variables for building Qt3 applications.

Note
This tool is only suitable for building targeted to Qt3, which
is obsolete (the tool is deprecated since 4.3). There are
contributed tools for Qt4 and Qt5, see
https://github.com/SCons/scons-contrib[1]. Qt4 has also passed
end of life for standard support (in Dec 2015).
Note paths for these construction variables are assembled using the
os.path.join method so they will have the appropriate separator at
runtime, but are listed here in the various entries only with the
'/' separator for simplicity.

In addition, the construction variables $CPPPATH, $LIBPATH and
$LIBS may be modified and the variables $PROGEMITTER, $SHLIBEMITTER
and $LIBEMITTER are modified. Because the build-performance is
affected when using this tool, you have to explicitly specify it at
Environment creation:

Environment(tools=['default','qt'])

The qt tool supports the following operations:

Automatic moc file generation from header files. You do not have
to specify moc files explicitly, the tool does it for you. However,
there are a few preconditions to do so: Your header file must have
the same filebase as your implementation file and must stay in the
same directory. It must have one of the suffixes .h, .hpp, .H,
.hxx, .hh. You can turn off automatic moc file generation by
setting $QT_AUTOSCAN to False. See also the corresponding Moc
Builder.

Automatic moc file generation from C++ files. As described in the
Qt documentation, include the moc file at the end of the C++ file.
Note that you have to include the file, which is generated by the
transformation ${QT_MOCCXXPREFIX}<basename>${QT_MOCCXXSUFFIX}, by
default <basename>.mo. A warning is generated after building the
moc file if you do not include the correct file. If you are using
VariantDir, you may need to specify duplicate=True. You can turn
off automatic moc file generation by setting $QT_AUTOSCAN to False.
See also the corresponding Moc Builder.

Automatic handling of .ui files. The implementation files
generated from .ui files are handled much the same as yacc or lex
files. Each .ui file given as a source of Program, Library or
SharedLibrary will generate three files: the declaration file, the
implementation file and a moc file. Because there are also
generated headers, you may need to specify duplicate=True in calls
to VariantDir. See also the corresponding Uic Builder.

Sets: $QTDIR, $QT_AUTOSCAN, $QT_BINPATH, $QT_CPPPATH, $QT_LIB,
$QT_LIBPATH, $QT_MOC, $QT_MOCCXXPREFIX, $QT_MOCCXXSUFFIX,
$QT_MOCFROMCXXCOM, $QT_MOCFROMCXXFLAGS, $QT_MOCFROMHCOM,
$QT_MOCFROMHFLAGS, $QT_MOCHPREFIX, $QT_MOCHSUFFIX, $QT_UIC,
$QT_UICCOM, $QT_UICDECLFLAGS, $QT_UICDECLPREFIX, $QT_UICDECLSUFFIX,
$QT_UICIMPLFLAGS, $QT_UICIMPLPREFIX, $QT_UICIMPLSUFFIX,
$QT_UISUFFIX.

Uses: $QTDIR.

rmic
Sets construction variables for the rmic utility.

Sets: $JAVACLASSSUFFIX, $RMIC, $RMICCOM, $RMICFLAGS.

Uses: $RMICCOMSTR.

rpcgen
Sets construction variables for building with RPCGEN.

Sets: $RPCGEN, $RPCGENCLIENTFLAGS, $RPCGENFLAGS,
$RPCGENHEADERFLAGS, $RPCGENSERVICEFLAGS, $RPCGENXDRFLAGS.

sgiar
Sets construction variables for the SGI library archiver.

Sets: $AR, $ARCOMSTR, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $SHLINK,
$SHLINKFLAGS.

Uses: $ARCOMSTR, $SHLINKCOMSTR.

sgic++
Sets construction variables for the SGI C++ compiler.

Sets: $CXX, $CXXFLAGS, $SHCXX, $SHOBJSUFFIX.

sgicc
Sets construction variables for the SGI C compiler.

Sets: $CXX, $SHOBJSUFFIX.

sgilink
Sets construction variables for the SGI linker.

Sets: $LINK, $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

sunar
Sets construction variables for the Sun library archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

Uses: $ARCOMSTR.

sunc++
Sets construction variables for the Sun C++ compiler.

Sets: $CXX, $CXXVERSION, $SHCXX, $SHCXXFLAGS, $SHOBJPREFIX,
$SHOBJSUFFIX.

suncc
Sets construction variables for the Sun C compiler.

Sets: $CXX, $SHCCFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

sunf77
Set construction variables for the Sun f77 Fortran compiler.

Sets: $F77, $FORTRAN, $SHF77, $SHF77FLAGS, $SHFORTRAN,
$SHFORTRANFLAGS.

sunf90
Set construction variables for the Sun f90 Fortran compiler.

Sets: $F90, $FORTRAN, $SHF90, $SHF90FLAGS, $SHFORTRAN,
$SHFORTRANFLAGS.

sunf95
Set construction variables for the Sun f95 Fortran compiler.

Sets: $F95, $FORTRAN, $SHF95, $SHF95FLAGS, $SHFORTRAN,
$SHFORTRANFLAGS.

sunlink
Sets construction variables for the Sun linker.

Sets: $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

swig
Sets construction variables for the SWIG interface compiler.

Sets: $SWIG, $SWIGCFILESUFFIX, $SWIGCOM, $SWIGCXXFILESUFFIX,
$SWIGDIRECTORSUFFIX, $SWIGFLAGS, $SWIGINCPREFIX, $SWIGINCSUFFIX,
$SWIGPATH, $SWIGVERSION, $_SWIGINCFLAGS.

Uses: $SWIGCOMSTR.

tar
Sets construction variables for the tar archiver.

Sets: $TAR, $TARCOM, $TARFLAGS, $TARSUFFIX.

Uses: $TARCOMSTR.

tex
Sets construction variables for the TeX formatter and typesetter.

Sets: $BIBTEX, $BIBTEXCOM, $BIBTEXFLAGS, $LATEX, $LATEXCOM,
$LATEXFLAGS, $MAKEINDEX, $MAKEINDEXCOM, $MAKEINDEXFLAGS, $TEX,
$TEXCOM, $TEXFLAGS.

Uses: $BIBTEXCOMSTR, $LATEXCOMSTR, $MAKEINDEXCOMSTR, $TEXCOMSTR.

textfile
Set construction variables for the Textfile and Substfile builders.

Sets: $LINESEPARATOR, $SUBSTFILEPREFIX, $SUBSTFILESUFFIX,
$TEXTFILEPREFIX, $TEXTFILESUFFIX.

Uses: $SUBST_DICT.

tlib
Sets construction variables for the Borlan tib library archiver.

Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

Uses: $ARCOMSTR.

xgettext
This scons tool is a part of scons gettext toolset. It provides
scons interface to xgettext(1) program, which extracts
internationalized messages from source code. The tool provides
POTUpdate builder to make PO Template files.

Sets: $POTSUFFIX, $POTUPDATE_ALIAS, $XGETTEXTCOM, $XGETTEXTCOMSTR,
$XGETTEXTFLAGS, $XGETTEXTFROM, $XGETTEXTFROMPREFIX,
$XGETTEXTFROMSUFFIX, $XGETTEXTPATH, $XGETTEXTPATHPREFIX,
$XGETTEXTPATHSUFFIX, $_XGETTEXTDOMAIN, $_XGETTEXTFROMFLAGS,
$_XGETTEXTPATHFLAGS.

Uses: $POTDOMAIN.

yacc
Sets construction variables for the yacc parse generator.

Sets: $YACC, $YACCCOM, $YACCFLAGS, $YACCHFILESUFFIX,
$YACCHXXFILESUFFIX, $YACCVCGFILESUFFIX.

Uses: $YACCCOMSTR, $YACCFLAGS, $YACC_GRAPH_FILE, $YACC_HEADER_FILE.

zip
Sets construction variables for the zip archiver.

Sets: $ZIP, $ZIPCOM, $ZIPCOMPRESSION, $ZIPFLAGS, $ZIPSUFFIX.

Uses: $ZIPCOMSTR.

Builder Methods
You tell SCons what to build by calling Builders, functions which take
particular action(s) to produce target(s) of a particular type
(conventionally hinted at by the builder name, e.g. Program) from the
specified source files. A builder call is a declaration: SCons enters
the specified relationship into its internal dependency node graph, and
only later makes the decision on whether anything is actually built,
since this depends on command-line options, target selection rules, and
whether the target(s) are out of date with respect to the sources.

SCons provides a number of builders, and you can also write your own
(see Builder Objects). Builders are created dynamically at run-time,
often (though not always) by tools which determine whether the external
dependencies for the builder are satisfied, and which perform the
necessary setup (see Tools). Builders are attached to a construction
environment as methods. The available builder methods are registered as
key-value pairs in the $BUILDERS attribute of the construction
environment, so the available builders can be examined. This example
displays them for debugging purposes:

env = Environment()
print("Builders:", list(env['BUILDERS']))

Builder methods take two required arguments: target and source. The
target and source arguments can be specified either as positional
arguments, in which case target comes first, or as keyword arguments,
using target= and source=. Although both arguments are nominally
required, if there is a single source and the target can be inferred
the target argument can be omitted (see below). Builder methods also
take a variety of keyword arguments, described below.

Because long lists of file names can lead to a lot of quoting in a
builder call, SCons supplies a Split global function and a same-named
environment method that splits a single string into a list, using
strings of white-space characters as the delimiter (similar to the
Python string split method, but succeeds even if the input isn't a
string).

The following are equivalent examples of calling the Program builder
method:

env.Program('bar', ['bar.c', 'foo.c'])
env.Program('bar', Split('bar.c foo.c'))
env.Program('bar', env.Split('bar.c foo.c'))
env.Program(source=['bar.c', 'foo.c'], target='bar')
env.Program(target='bar', source=Split('bar.c foo.c'))
env.Program(target='bar', source=env.Split('bar.c foo.c'))
env.Program('bar', source='bar.c foo.c'.split())

Sources and targets can be specified as a scalar or as a list, composed
of either strings or nodes (more on nodes below). When specifying path
strings, Python follows the POSIX pathname convention: if a string
begins with the operating system pathname separator (on Windows both
the slash and backslash separator are accepted, and any leading drive
specifier is ignored for the determination) it is considered an
absolute path, otherwise it is a relative path. If the path string
contains no separator characters, it is searched for as a file in the
current directory. If it contains separator characters, the search
follows down from the starting point, which is the top of the directory
tree for an absolute path and the current directory for a relative
path. The "current directory" in this context is the directory of the
SConscript file currently being processed.

SCons also recognizes a third way to specify path strings: if the
string begins with the # character it is top-relative - it works like a
relative path but the search follows down from the directory containing
the top-level SConstruct rather than from the current directory. The #
can optionally be followed by a pathname separator, which is ignored if
found in that position. Top-relative paths only work in places where
scons will interpret the path (see some examples below). To be used in
other contexts the string will need to be converted to a relative or
absolute path first.

Examples:

# The comments describing the targets that will be built
# assume these calls are in a SConscript file in the
# a subdirectory named "subdir".

# Builds the program "subdir/foo" from "subdir/foo.c":
env.Program('foo', 'foo.c')

# Builds the program "/tmp/bar" from "subdir/bar.c":
env.Program('/tmp/bar', 'bar.c')

# An initial '#' or '#/' are equivalent; the following
# calls build the programs "foo" and "bar" (in the
# top-level SConstruct directory) from "subdir/foo.c" and
# "subdir/bar.c", respectively:
env.Program('#foo', 'foo.c')
env.Program('#/bar', 'bar.c')

# Builds the program "other/foo" (relative to the top-level
# SConstruct directory) from "subdir/foo.c":
env.Program('#other/foo', 'foo.c')

# This will not work, only SCons interfaces understand '#',
# os.path.exists is pure Python:
if os.path.exists('#inc/foo.h'):
env.Append(CPPPATH='#inc')

When the target shares the same base name as the source and only the
suffix varies, and if the builder method has a suffix defined for the
target file type, then the target argument may be omitted completely,
and scons will deduce the target file name from the source file name.
The following examples all build the executable program bar (on POSIX
systems) or bar.exe (on Windows systems) from the bar.c source file:

env.Program(target='bar', source='bar.c')
env.Program('bar', source='bar.c')
env.Program(source='bar.c')
env.Program('bar.c')

The optional srcdir keyword argument specifies that all source file
strings that are not absolute paths or top-relative paths shall be
interpreted relative to the specified srcdir. The following example
will build the build/prog (or build/prog.exe on Windows) program from
the files src/f1.c and src/f2.c:

env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src')

The optional parse_flags keyword argument causes behavior similar to
the env.MergeFlags method, where the argument value is broken into
individual settings and merged into the appropriate construction
variables.

env.Program('hello', 'hello.c', parse_flags='-Iinclude -DEBUG -lm')

This example adds 'include' to the $CPPPATH construction variable,
'EBUG' to $CPPDEFINES, and 'm' to $LIBS.

The optional chdir keyword argument specifies that the Builder's
action(s) should be executed after changing directory. If the chdir
argument is a path string or a directory Node, scons will change to the
specified directory. If the chdir is not a string or Node and evaluates
true, then scons will change to the target file's directory.

Warning
Python only keeps one current directory location even if there are
multiple threads. This means that use of the chdir argument will
not work with the SCons -j option, because individual worker
threads spawned by SCons interfere with each other when they start
changing directory.

# scons will change to the "sub" subdirectory
# before executing the "cp" command.
env.Command(
target='sub/dir/foo.out',
source='sub/dir/foo.in',
action="cp dir/foo.in dir/foo.out",
chdir='sub',
)

# Because chdir is not a string, scons will change to the
# target's directory ("sub/dir") before executing the
# "cp" command.
env.Command('sub/dir/foo.out', 'sub/dir/foo.in', "cp foo.in foo.out", chdir=True)

Note that SCons will not automatically modify its expansion of
construction variables like $TARGET and $SOURCE when using the chdir
keyword argument--that is, the expanded file names will still be
relative to the top-level directory where the SConstruct was found, and
consequently incorrect relative to the chdir directory. If you use the
chdir keyword argument, you will typically need to supply a different
command line using expansions like ${TARGET.file} and ${SOURCE.file} to
use just the filename portion of the target and source.

Keyword arguments that are not specifically recognized are treated as
construction variable overrides, which replace or add those variables
on a limited basis. These overrides will only be in effect when
building the target of the builder call, and will not affect other
parts of the build. For example, if you want to specify some libraries
needed by just one program:

env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

or generate a shared library with a non-standard suffix:

env.SharedLibrary(
target='word',
source='word.cpp',
SHLIBSUFFIX='.ocx',
LIBSUFFIXES=['.ocx'],
)

Note that both the $SHLIBSUFFIX and $LIBSUFFIXES construction variables
must be set if you want scons to search automatically for dependencies
on the non-standard library names; see the descriptions of these
variables for more information.

Although the builder methods defined by scons are, in fact, methods of
a construction environment object, many may also be called without an
explicit environment:

Program('hello', 'hello.c')
SharedLibrary('word', 'word.cpp')

If called this way, the builder will internally use the Default
Environment that consists of the tools and values that scons has
determined are appropriate for the local system.

Builder methods that can be called without an explicit environment
(indicated in the listing of builders below without a leading env.) may
be called from custom Python modules that you import into an SConscript
file by adding the following to the Python module:

from SCons.Script import *

A builder may add additional targets beyond those requested if an
attached Emitter chooses to do so (see the section called “Builder
Objects” for more information. $PROGEMITTER is an example). For
example, the GNU linker takes a command-line argument -Map=mapfile,
which causes it to produce a linker map file in addition to the
executable file actually being linked. If the Program builder's emitter
is configured to add this mapfile if the option is set, then two
targets will be returned when you only provided for one.

For this reason, builder methods always return a NodeList, a list-like
object whose elements are Nodes. Nodes are the internal representation
of build targets or sources (see the section called “Node Objects” for
more information). The returned NodeList object can be passed to other
builder methods as source(s) or to other SCons functions or methods
where a path string would normally be accepted.

For example, to add a specific preprocessor define when compiling one
specific object file but not the others:

bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
env.Program("prog", ['foo.c', bar_obj_list, 'main.c'])

Using a Node as in this example makes for a more portable build by
avoiding having to specify a platform-specific object suffix when
calling the Program builder method.

The NodeList object is also convenient to pass to the Default function,
for the same reason of avoiding a platform-specific name:

tgt = env.Program("prog", ["foo.c", "bar.c", "main.c"])
Default(tgt)

Builder calls will automatically "flatten" lists passed as source and
target, so they are free to contain elements which are themselves
lists, such as bar_obj_list returned by the StaticObject call. If you
need to manipulate a list of lists returned by builders directly in
Python code, you can either build a new list by hand:

foo = Object('foo.c')
bar = Object('bar.c')
objects = ['begin.o'] + foo + ['middle.o'] + bar + ['end.o']
for obj in objects:
print(str(obj))

Or you can use the Flatten function supplied by SCons to create a list
containing just the Nodes, which may be more convenient:

foo = Object('foo.c')
bar = Object('bar.c')
objects = Flatten(['begin.o', foo, 'middle.o', bar, 'end.o'])
for obj in objects:
print(str(obj))

Since builder calls return a list-like object, not an actual Python
list, it is not appropriate to use the Python add operator (+ or +=) to
append builder results to a Python list. Because the list and the
object are different types, Python will not update the original list in
place, but will instead create a new NodeList object containing the
concatenation of the list elements and the builder results. This will
cause problems for any other Python variables in your SCons
configuration that still hold on to a reference to the original list.
Instead, use the Python list extend method to make sure the list is
updated in-place. Example:

object_files = []

# Do NOT use += here:
# object_files += Object('bar.c')
#
# It will not update the object_files list in place.
#
# Instead, use the list extend method:
object_files.extend(Object('bar.c'))

The path name for a Node's file may be used by passing the Node to
Python's builtin str function:

bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
print("The path to bar_obj is:", str(bar_obj_list[0]))

Note that because the Builder call returns a NodeList, you have to
access the first element in the list (bar_obj_list[0] in the example)
to get at the Node that actually represents the object file.

When trying to handle errors that may occur in a builder method,
consider that the corresponding Action is executed at a different time
than the SConscript file statement calling the builder. It is not
useful to wrap a builder call in a try block, since success in the
builder call is not the same as the builder itself succeeding. If
necessary, a Builder's Action should be coded to exit with a useful
exception message indicating the problem in the SConscript files -
programmatically recovering from build errors is rarely useful.

The following builder methods are predefined in the SCons core software
distribution. Depending on the setup of a particular construction
environment and on the type and software installation status of the
underlying system, not all builders may be available in that
construction environment. Since the function calling signature is the
same for all builders:

Buildername(target, source, [key=val, ...])

it is omitted in this listing for brevity.

CFile(), env.CFile()
Builds a C source file given a lex (.l) or yacc (.y) input file.
The suffix specified by the $CFILESUFFIX construction variable (.c
by default) is automatically added to the target if it is not
already present. Example:

# builds foo.c
env.CFile(target = 'foo.c', source = 'foo.l')
# builds bar.c
env.CFile(target = 'bar', source = 'bar.y')

Command(), env.Command()
The Command "Builder" is actually a function that looks like a
Builder, but takes a required third argument, which is the action
to take to construct the target from the source, used for "one-off"
builds where a full builder is not needed. Thus it does not follow
the builder calling rules described at the start of this section.
See instead the Command function description for the calling syntax
and details.

CompilationDatabase(), env.CompilationDatabase()

CompilationDatabase is a special builder which adds a target to
create a JSON formatted compilation database compatible with clang
tooling (see the LLVM specification[2]). This database is suitable
for consumption by various tools and editors who can use it to
obtain build and dependency information which otherwise would be
internal to SCons. The builder does not require any source files to
be specified, rather it arranges to emit information about all of
the C, C++ and assembler source/output pairs identified in the
build that are not excluded by the optional filter
$COMPILATIONDB_PATH_FILTER. The target is subject to the usual
SCons target selection rules.

If called with no arguments, the builder will default to a target
name of compile_commands.json.

If called with a single positional argument, scons will "deduce"
the target name from that source argument, giving it the same name,
and then ignore the source. This is the usual way to call the
builder if a non-default target name is wanted.

If called with either the target= or source= keyword arguments, the
value of the argument is taken as the target name. If called with
both, the target= value is used and source= is ignored. If called
with multiple sources, the source list will be ignored, since there
is no way to deduce what the intent was; in this case the default
target name will be used.

Note
You must load the compilation_db tool prior to specifying any
part of your build or some source/output files will not show up
in the compilation database.
Available since scons 4.0.

CXXFile(), env.CXXFile()
Builds a C++ source file given a lex (.ll) or yacc (.yy) input
file. The suffix specified by the $CXXFILESUFFIX construction
variable (.cc by default) is automatically added to the target if
it is not already present. Example:

# builds foo.cc
env.CXXFile(target = 'foo.cc', source = 'foo.ll')
# builds bar.cc
env.CXXFile(target = 'bar', source = 'bar.yy')

DocbookEpub(), env.DocbookEpub()
A pseudo-Builder, providing a Docbook toolchain for EPUB output.

env = Environment(tools=['docbook'])
env.DocbookEpub('manual.epub', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookEpub('manual')

DocbookHtml(), env.DocbookHtml()
A pseudo-Builder, providing a Docbook toolchain for HTML output.

env = Environment(tools=['docbook'])
env.DocbookHtml('manual.html', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookHtml('manual')

DocbookHtmlChunked(), env.DocbookHtmlChunked()
A pseudo-Builder providing a Docbook toolchain for chunked HTML
output. It supports the base.dir parameter. The chunkfast.xsl file
(requires "EXSLT") is used as the default stylesheet. Basic syntax:

env = Environment(tools=['docbook'])
env.DocbookHtmlChunked('manual')

where manual.xml is the input file.

If you use the root.filename parameter in your own stylesheets you
have to specify the new target name. This ensures that the
dependencies get correct, especially for the cleanup via “scons
-c”:

env = Environment(tools=['docbook'])
env.DocbookHtmlChunked('mymanual.html', 'manual', xsl='htmlchunk.xsl')

Some basic support for the base.dir parameter is provided. You can
add the base_dir keyword to your Builder call, and the given prefix
gets prepended to all the created filenames:

env = Environment(tools=['docbook'])
env.DocbookHtmlChunked('manual', xsl='htmlchunk.xsl', base_dir='output/')

Make sure that you don't forget the trailing slash for the base
folder, else your files get renamed only!

DocbookHtmlhelp(), env.DocbookHtmlhelp()
A pseudo-Builder, providing a Docbook toolchain for HTMLHELP
output. Its basic syntax is:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('manual')

where manual.xml is the input file.

If you use the root.filename parameter in your own stylesheets you
have to specify the new target name. This ensures that the
dependencies get correct, especially for the cleanup via “scons
-c”:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('mymanual.html', 'manual', xsl='htmlhelp.xsl')

Some basic support for the base.dir parameter is provided. You can
add the base_dir keyword to your Builder call, and the given prefix
gets prepended to all the created filenames:

env = Environment(tools=['docbook'])
env.DocbookHtmlhelp('manual', xsl='htmlhelp.xsl', base_dir='output/')

Make sure that you don't forget the trailing slash for the base
folder, else your files get renamed only!

DocbookMan(), env.DocbookMan()
A pseudo-Builder, providing a Docbook toolchain for Man page
output. Its basic syntax is:

env = Environment(tools=['docbook'])
env.DocbookMan('manual')

where manual.xml is the input file. Note, that you can specify a
target name, but the actual output names are automatically set from
the refname entries in your XML source.

DocbookPdf(), env.DocbookPdf()
A pseudo-Builder, providing a Docbook toolchain for PDF output.

env = Environment(tools=['docbook'])
env.DocbookPdf('manual.pdf', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookPdf('manual')

DocbookSlidesHtml(), env.DocbookSlidesHtml()
A pseudo-Builder, providing a Docbook toolchain for HTML slides
output.

env = Environment(tools=['docbook'])
env.DocbookSlidesHtml('manual')

If you use the titlefoil.html parameter in your own stylesheets you
have to give the new target name. This ensures that the
dependencies get correct, especially for the cleanup via “scons
-c”:

env = Environment(tools=['docbook'])
env.DocbookSlidesHtml('mymanual.html','manual', xsl='slideshtml.xsl')

Some basic support for the base.dir parameter is provided. You can
add the base_dir keyword to your Builder call, and the given prefix
gets prepended to all the created filenames:

env = Environment(tools=['docbook'])
env.DocbookSlidesHtml('manual', xsl='slideshtml.xsl', base_dir='output/')

Make sure that you don't forget the trailing slash for the base
folder, else your files get renamed only!

DocbookSlidesPdf(), env.DocbookSlidesPdf()
A pseudo-Builder, providing a Docbook toolchain for PDF slides
output.

env = Environment(tools=['docbook'])
env.DocbookSlidesPdf('manual.pdf', 'manual.xml')

or simply

env = Environment(tools=['docbook'])
env.DocbookSlidesPdf('manual')

DocbookXInclude(), env.DocbookXInclude()
A pseudo-Builder, for resolving XIncludes in a separate processing
step.

env = Environment(tools=['docbook'])
env.DocbookXInclude('manual_xincluded.xml', 'manual.xml')

DocbookXslt(), env.DocbookXslt()
A pseudo-Builder, applying a given XSL transformation to the input
file.

env = Environment(tools=['docbook'])
env.DocbookXslt('manual_transformed.xml', 'manual.xml', xsl='transform.xslt')

Note, that this builder requires the xsl parameter to be set.

DVI(), env.DVI()
Builds a .dvi file from a .tex, .ltx or .latex input file. If the
source file suffix is .tex, scons will examine the contents of the
file; if the string \documentclass or \documentstyle is found, the
file is assumed to be a LaTeX file and the target is built by
invoking the $LATEXCOM command line; otherwise, the $TEXCOM command
line is used. If the file is a LaTeX file, the DVI builder method
will also examine the contents of the .aux file and invoke the
$BIBTEX command line if the string bibdata is found, start
$MAKEINDEX to generate an index if a .ind file is found and will
examine the contents .log file and re-run the $LATEXCOM command if
the log file says it is necessary.

The suffix .dvi (hard-coded within TeX itself) is automatically
added to the target if it is not already present. Examples:

# builds from aaa.tex
env.DVI(target = 'aaa.dvi', source = 'aaa.tex')
# builds bbb.dvi
env.DVI(target = 'bbb', source = 'bbb.ltx')
# builds from ccc.latex
env.DVI(target = 'ccc.dvi', source = 'ccc.latex')

Gs(), env.Gs()
A Builder for explicitly calling the gs executable. Depending on
the underlying OS, the different names gs, gsos2 and gswin32c are
tried.

env = Environment(tools=['gs'])
env.Gs(
'cover.jpg',
'scons-scons.pdf',
GSFLAGS='-dNOPAUSE -dBATCH -sDEVICE=jpeg -dFirstPage=1 -dLastPage=1 -q',
)

Install(), env.Install()
Installs one or more source files or directories in the specified
target, which must be a directory. The names of the specified
source files or directories remain the same within the destination
directory. The sources may be given as a string or as a node
returned by a builder.

env.Install(target='/usr/local/bin', source=['foo', 'bar'])

Note that if target paths chosen for the Install builder (and the
related InstallAs and InstallVersionedLib builders) are outside the
project tree, such as in the example above, they may not be
selected for "building" by default, since in the absence of other
instructions scons builds targets that are underneath the top
directory (the directory that contains the SConstruct file, usually
the current directory). Use command line targets or the Default
function in this case.

If the --install-sandbox command line option is given, the target
directory will be prefixed by the directory path specified. This is
useful to test installs without installing to a "live" location in
the system.

See also FindInstalledFiles. For more thoughts on installation, see
the User Guide (particularly the section on Command-Line Targets
and the chapters on Installing Files and on Alias Targets).

InstallAs(), env.InstallAs()
Installs one or more source files or directories to specific names,
allowing changing a file or directory name as part of the
installation. It is an error if the target and source arguments
list different numbers of files or directories.

env.InstallAs(target='/usr/local/bin/foo',
source='foo_debug')
env.InstallAs(target=['../lib/libfoo.a', '../lib/libbar.a'],
source=['libFOO.a', 'libBAR.a'])

See the note under Install.

InstallVersionedLib(), env.InstallVersionedLib()
Installs a versioned shared library. The symlinks appropriate to
the architecture will be generated based on symlinks of the source
library.

env.InstallVersionedLib(target='/usr/local/bin/foo',
source='libxyz.1.5.2.so')

See the note under Install.

Jar(), env.Jar()
Builds a Java archive (.jar) file from the specified list of
sources. Any directories in the source list will be searched for
.class files). Any .java files in the source list will be compiled
to .class files by calling the Java Builder.

If the $JARCHDIR value is set, the jar command will change to the
specified directory using the -C option. If $JARCHDIR is not set
explicitly, SCons will use the top of any subdirectory tree in
which Java .class were built by the Java Builder.

If the contents any of the source files begin with the string
Manifest-Version, the file is assumed to be a manifest and is
passed to the jar command with the m option set.

env.Jar(target = 'foo.jar', source = 'classes')

env.Jar(target = 'bar.jar',
source = ['bar1.java', 'bar2.java'])

Java(), env.Java()
Builds one or more Java class files. The sources may be any
combination of explicit .java files, or directory trees which will
be scanned for .java files.

SCons will parse each source .java file to find the classes
(including inner classes) defined within that file, and from that
figure out the target .class files that will be created. The class
files will be placed underneath the specified target directory.

SCons will also search each Java file for the Java package name,
which it assumes can be found on a line beginning with the string
package in the first column; the resulting .class files will be
placed in a directory reflecting the specified package name. For
example, the file Foo.java defining a single public Foo class and
containing a package name of sub.dir will generate a corresponding
sub/dir/Foo.class class file.

Examples:

env.Java(target = 'classes', source = 'src')
env.Java(target = 'classes', source = ['src1', 'src2'])
env.Java(target = 'classes', source = ['File1.java', 'File2.java'])

Java source files can use the native encoding for the underlying
OS. Since SCons compiles in simple ASCII mode by default, the
compiler will generate warnings about unmappable characters, which
may lead to errors as the file is processed further. In this case,
the user must specify the LANG environment variable to tell the
compiler what encoding is used. For portibility, it's best if the
encoding is hard-coded so that the compile will work if it is done
on a system with a different encoding.

env = Environment()
env['ENV']['LANG'] = 'en_GB.UTF-8'

JavaH(), env.JavaH()
Builds C header and source files for implementing Java native
methods. The target can be either a directory in which the header
files will be written, or a header file name which will contain all
of the definitions. The source can be the names of .class files,
the names of .java files to be compiled into .class files by
calling the Java builder method, or the objects returned from the
Java builder method.

If the construction variable $JAVACLASSDIR is set, either in the
environment or in the call to the JavaH builder method itself, then
the value of the variable will be stripped from the beginning of
any .class file names.

Examples:

# builds java_native.h
classes = env.Java(target="classdir", source="src")
env.JavaH(target="java_native.h", source=classes)

# builds include/package_foo.h and include/package_bar.h
env.JavaH(target="include", source=["package/foo.class", "package/bar.class"])

# builds export/foo.h and export/bar.h
env.JavaH(
target="export",
source=["classes/foo.class", "classes/bar.class"],
JAVACLASSDIR="classes",
)

Note
Java versions starting with 10.0 no longer use the javah
command for generating JNI headers/sources, and indeed have
removed the command entirely (see Java Enhancement Proposal JEP
313[3]), making this tool harder to use for that purpose.
SCons may autodiscover a javah belonging to an older release if
there are multiple Java versions on the system, which will lead
to incorrect results. To use with a newer Java, override the
default values of $JAVAH (to contain the path to the javac) and
$JAVAHFLAGS (to contain at least a -h flag) and note that
generating headers with javac requires supplying source .java
files only, not .class files.

Library(), env.Library()
A synonym for the StaticLibrary builder method.

LoadableModule(), env.LoadableModule()
On most systems, this is the same as SharedLibrary. On Mac OS X
(Darwin) platforms, this creates a loadable module bundle.

M4(), env.M4()
Builds an output file from an M4 input file. This uses a default
$M4FLAGS value of -E, which considers all warnings to be fatal and
stops on the first warning when using the GNU version of m4.
Example:

env.M4(target = 'foo.c', source = 'foo.c.m4')

Moc(), env.Moc()
Builds an output file from a moc input file. moc input files are
either header files or C++ files. This builder is only available
after using the tool qt. See the $QTDIR variable for more
information. Example:

env.Moc('foo.h') # generates moc_foo.cc
env.Moc('foo.cpp') # generates foo.moc

MOFiles(), env.MOFiles()
This builder belongs to msgfmt tool. The builder compiles PO files
to MO files.

Example 1. Create pl.mo and en.mo by compiling pl.po and en.po:

# ...
env.MOFiles(['pl', 'en'])

Example 2. Compile files for languages defined in LINGUAS file:

# ...
env.MOFiles(LINGUAS_FILE = 1)

Example 3. Create pl.mo and en.mo by compiling pl.po and en.po plus
files for languages defined in LINGUAS file:

# ...
env.MOFiles(['pl', 'en'], LINGUAS_FILE = 1)

Example 4. Compile files for languages defined in LINGUAS file
(another version):

# ...
env['LINGUAS_FILE'] = 1
env.MOFiles()

MSVSProject(), env.MSVSProject()
Builds a Microsoft Visual Studio project file, and by default
builds a solution file as well.

This builds a Visual Studio project file, based on the version of
Visual Studio that is configured (either the latest installed
version, or the version specified by $MSVS_VERSION in the
Environment constructor). For Visual Studio 6, it will generate a
.dsp file. For Visual Studio 7, 8, and 9, it will generate a
.vcproj file. For Visual Studio 10 and later, it will generate a
.vcxproj file.

By default, this also generates a solution file for the specified
project, a .dsw file for Visual Studio 6 or a .sln file for Visual
Studio 7 and later. This behavior may be disabled by specifying
auto_build_solution=0 when you call MSVSProject, in which case you
presumably want to build the solution file(s) by calling the
MSVSSolution Builder (see below).

The MSVSProject builder takes several lists of filenames to be
placed into the project file. These are currently limited to srcs,
incs, localincs, resources, and misc. These are pretty
self-explanatory, but it should be noted that these lists are added
to the $SOURCES construction variable as strings, NOT as SCons File
Nodes. This is because they represent file names to be added to the
project file, not the source files used to build the project file.

The above filename lists are all optional, although at least one
must be specified for the resulting project file to be non-empty.

In addition to the above lists of values, the following values may
be specified:

target
The name of the target .dsp or .vcproj file. The correct suffix
for the version of Visual Studio must be used, but the
$MSVSPROJECTSUFFIX construction variable will be defined to the
correct value (see example below).

variant
The name of this particular variant. For Visual Studio 7
projects, this can also be a list of variant names. These are
typically things like "Debug" or "Release", but really can be
anything you want. For Visual Studio 7 projects, they may also
specify a target platform separated from the variant name by a
| (vertical pipe) character: Debug|Xbox. The default target
platform is Win32. Multiple calls to MSVSProject with different
variants are allowed; all variants will be added to the project
file with their appropriate build targets and sources.

cmdargs
Additional command line arguments for the different variants.
The number of cmdargs entries must match the number of variant
entries, or be empty (not specified). If you give only one, it
will automatically be propagated to all variants.

cppdefines
Preprocessor definitions for the different variants. The number
of cppdefines entries must match the number of variant entries,
or be empty (not specified). If you give only one, it will
automatically be propagated to all variants. If you don't give
this parameter, SCons will use the invoking environment's
CPPDEFINES entry for all variants.

cppflags
Compiler flags for the different variants. If a /std:c++ flag
is found then /Zc:__cplusplus is appended to the flags if not
already found, this ensures that intellisense uses the /std:c++
switch. The number of cppflags entries must match the number of
variant entries, or be empty (not specified). If you give only
one, it will automatically be propagated to all variants. If
you don't give this parameter, SCons will combine the invoking
environment's CCFLAGS, CXXFLAGS, CPPFLAGS entries for all
variants.

cpppaths
Compiler include paths for the different variants. The number
of cpppaths entries must match the number of variant entries,
or be empty (not specified). If you give only one, it will
automatically be propagated to all variants. If you don't give
this parameter, SCons will use the invoking environment's
CPPPATH entry for all variants.

buildtarget
An optional string, node, or list of strings or nodes (one per
build variant), to tell the Visual Studio debugger what output
target to use in what build variant. The number of buildtarget
entries must match the number of variant entries.

runfile
The name of the file that Visual Studio 7 and later will run
and debug. This appears as the value of the Output field in the
resulting Visual Studio project file. If this is not specified,
the default is the same as the specified buildtarget value.

Note that because SCons always executes its build commands from the
directory in which the SConstruct file is located, if you generate
a project file in a different directory than the SConstruct
directory, users will not be able to double-click on the file name
in compilation error messages displayed in the Visual Studio
console output window. This can be remedied by adding the Visual
C/C++ /FC compiler option to the $CCFLAGS variable so that the
compiler will print the full path name of any files that cause
compilation errors.

Example usage:

barsrcs = ['bar.cpp']
barincs = ['bar.h']
barlocalincs = ['StdAfx.h']
barresources = ['bar.rc','resource.h']
barmisc = ['bar_readme.txt']

dll = env.SharedLibrary(target='bar.dll',
source=barsrcs)
buildtarget = [s for s in dll if str(s).endswith('dll')]
env.MSVSProject(target='Bar' + env['MSVSPROJECTSUFFIX'],
srcs=barsrcs,
incs=barincs,
localincs=barlocalincs,
resources=barresources,
misc=barmisc,
buildtarget=buildtarget,
variant='Release')

Starting with version 2.4 of SCons it is also possible to specify
the optional argument DebugSettings, which creates files for
debugging under Visual Studio:

DebugSettings
A dictionary of debug settings that get written to the
.vcproj.user or the .vcxproj.user file, depending on the
version installed. As it is done for cmdargs (see above), you
can specify a DebugSettings dictionary per variant. If you give
only one, it will be propagated to all variants.

Currently, only Visual Studio v9.0 and Visual Studio version v11
are implemented, for other versions no file is generated. To
generate the user file, you just need to add a DebugSettings
dictionary to the environment with the right parameters for your
MSVS version. If the dictionary is empty, or does not contain any
good value, no file will be generated.

Following is a more contrived example, involving the setup of a
project for variants and DebugSettings:

# Assuming you store your defaults in a file
vars = Variables('variables.py')
msvcver = vars.args.get('vc', '9')

# Check command args to force one Microsoft Visual Studio version
if msvcver == '9' or msvcver == '11':
env = Environment(MSVC_VERSION=msvcver+'.0', MSVC_BATCH=False)
else:
env = Environment()

AddOption('--userfile', action='store_true', dest='userfile', default=False,
help="Create Visual Studio Project user file")

#
# 1. Configure your Debug Setting dictionary with options you want in the list
# of allowed options, for instance if you want to create a user file to launch
# a specific application for testing your dll with Microsoft Visual Studio 2008 (v9):
#
V9DebugSettings = {
'Command':'c:\\myapp\\using\\thisdll.exe',
'WorkingDirectory': 'c:\\myapp\\using\\',
'CommandArguments': '-p password',
# 'Attach':'false',
# 'DebuggerType':'3',
# 'Remote':'1',
# 'RemoteMachine': None,
# 'RemoteCommand': None,
# 'HttpUrl': None,
# 'PDBPath': None,
# 'SQLDebugging': None,
# 'Environment': '',
# 'EnvironmentMerge':'true',
# 'DebuggerFlavor': None,
# 'MPIRunCommand': None,
# 'MPIRunArguments': None,
# 'MPIRunWorkingDirectory': None,
# 'ApplicationCommand': None,
# 'ApplicationArguments': None,
# 'ShimCommand': None,
# 'MPIAcceptMode': None,
# 'MPIAcceptFilter': None,
}

#
# 2. Because there are a lot of different options depending on the Microsoft
# Visual Studio version, if you use more than one version you have to
# define a dictionary per version, for instance if you want to create a user
# file to launch a specific application for testing your dll with Microsoft
# Visual Studio 2012 (v11):
#
V10DebugSettings = {
'LocalDebuggerCommand': 'c:\\myapp\\using\\thisdll.exe',
'LocalDebuggerWorkingDirectory': 'c:\\myapp\\using\\',
'LocalDebuggerCommandArguments': '-p password',
# 'LocalDebuggerEnvironment': None,
# 'DebuggerFlavor': 'WindowsLocalDebugger',
# 'LocalDebuggerAttach': None,
# 'LocalDebuggerDebuggerType': None,
# 'LocalDebuggerMergeEnvironment': None,
# 'LocalDebuggerSQLDebugging': None,
# 'RemoteDebuggerCommand': None,
# 'RemoteDebuggerCommandArguments': None,
# 'RemoteDebuggerWorkingDirectory': None,
# 'RemoteDebuggerServerName': None,
# 'RemoteDebuggerConnection': None,
# 'RemoteDebuggerDebuggerType': None,
# 'RemoteDebuggerAttach': None,
# 'RemoteDebuggerSQLDebugging': None,
# 'DeploymentDirectory': None,
# 'AdditionalFiles': None,
# 'RemoteDebuggerDeployDebugCppRuntime': None,
# 'WebBrowserDebuggerHttpUrl': None,
# 'WebBrowserDebuggerDebuggerType': None,
# 'WebServiceDebuggerHttpUrl': None,
# 'WebServiceDebuggerDebuggerType': None,
# 'WebServiceDebuggerSQLDebugging': None,
}

#
# 3. Select the dictionary you want depending on the version of visual Studio
# Files you want to generate.
#
if not env.GetOption('userfile'):
dbgSettings = None
elif env.get('MSVC_VERSION', None) == '9.0':
dbgSettings = V9DebugSettings
elif env.get('MSVC_VERSION', None) == '11.0':
dbgSettings = V10DebugSettings
else:
dbgSettings = None

#
# 4. Add the dictionary to the DebugSettings keyword.
#
barsrcs = ['bar.cpp', 'dllmain.cpp', 'stdafx.cpp']
barincs = ['targetver.h']
barlocalincs = ['StdAfx.h']
barresources = ['bar.rc','resource.h']
barmisc = ['ReadMe.txt']

dll = env.SharedLibrary(target='bar.dll',
source=barsrcs)

env.MSVSProject(target='Bar' + env['MSVSPROJECTSUFFIX'],
srcs=barsrcs,
incs=barincs,
localincs=barlocalincs,
resources=barresources,
misc=barmisc,
buildtarget=[dll[0]] * 2,
variant=('Debug|Win32', 'Release|Win32'),
cmdargs='vc=%s' % msvcver,
DebugSettings=(dbgSettings, {}))

MSVSSolution(), env.MSVSSolution()
Builds a Microsoft Visual Studio solution file.

This builds a Visual Studio solution file, based on the version of
Visual Studio that is configured (either the latest installed
version, or the version specified by $MSVS_VERSION in the
construction environment). For Visual Studio 6, it will generate a
.dsw file. For Visual Studio 7 (.NET), it will generate a .sln
file.

The following values must be specified:

target
The name of the target .dsw or .sln file. The correct suffix
for the version of Visual Studio must be used, but the value
$MSVSSOLUTIONSUFFIX will be defined to the correct value (see
example below).

variant
The name of this particular variant, or a list of variant names
(the latter is only supported for MSVS 7 solutions). These are
typically things like "Debug" or "Release", but really can be
anything you want. For MSVS 7 they may also specify target
platform, like this "Debug|Xbox". Default platform is Win32.

projects
A list of project file names, or Project nodes returned by
calls to the MSVSProject Builder, to be placed into the
solution file. It should be noted that these file names are NOT
added to the $SOURCES environment variable in form of files,
but rather as strings. This is because they represent file
names to be added to the solution file, not the source files
used to build the solution file.

Example Usage:

env.MSVSSolution(
target="Bar" + env["MSVSSOLUTIONSUFFIX"],
projects=["bar" + env["MSVSPROJECTSUFFIX"]],
variant="Release",
)

Ninja(), env.Ninja()
A special builder which adds a target to create a Ninja build file.
The builder does not require any source files to be specified.

Note
This is an experimental feature. To enable it you must use one
of the following methods

# On the command line
--experimental=ninja

# Or in your SConstruct
SetOption('experimental', 'ninja')

This functionality is subject to change and/or removal without
deprecation cycle.

To use this tool you need to install the Python ninja package,
as the tool by default depends on being able to do an import of
the package This can be done via:

python -m pip install ninja

If called with no arguments, the builder will default to a target
name of ninja.build.

Available since scons 4.2.

Object(), env.Object()
A synonym for the StaticObject builder method.

Package(), env.Package()
Builds software distribution packages. A package is a container
format which includes files to install along with metadata.
Packaging is optional, and must be enabled by specifying the
packaging tool. For example:

env = Environment(tools=['default', 'packaging'])

SCons can build packages in a number of well known packaging
formats. The target package type may be selected with the the
$PACKAGETYPE construction variable or the --package-type command
line option. The package type may be a list, in which case SCons
will attempt to build packages for each type in the list. Example:

env.Package(PACKAGETYPE=['src_zip', 'src_targz'], ...other args...)

The currently supported packagers are:

┌───────────┬────────────────────────────┐
│msi │ Microsoft Installer │
│ │ package │
├───────────┼────────────────────────────┤
│rpm │ RPM Package Manger package │
├───────────┼────────────────────────────┤
│ipkg │ Itsy Package Management │
│ │ package │
├───────────┼────────────────────────────┤
│tarbz2 │ bzip2-compressed tar file │
├───────────┼────────────────────────────┤
│targz │ gzip-compressed tar file │
├───────────┼────────────────────────────┤
│tarxz │ xz-compressed tar file │
├───────────┼────────────────────────────┤
│zip │ zip file │
├───────────┼────────────────────────────┤
│src_tarbz2 │ bzip2-compressed tar file │
│ │ suitable as source to │
│ │ another packager │
├───────────┼────────────────────────────┤
│src_targz │ gzip-compressed tar file │
│ │ suitable as source to │
│ │ another packager │
├───────────┼────────────────────────────┤
│src_tarxz │ xz-compressed tar file │
│ │ suitable as source to │
│ │ another packager │
├───────────┼────────────────────────────┤
│src_zip │ zip file suitable as │
│ │ source to another packager │
└───────────┴────────────────────────────┘
The file list to include in the package may be specified with the
source keyword argument. If omitted, the FindInstalledFiles
function is called behind the scenes to select all files that have
an Install, InstallAs or InstallVersionedLib Builder attached. If
the target keyword argument is omitted, the target name(s) will be
deduced from the package type(s).

The metadata comes partly from attributes of the files to be
packaged, and partly from packaging tags. Tags can be passed as
keyword arguments to the Package builder call, and may also be
attached to files (or more accurately, Nodes representing files)
with the Tag function. Some package-level tags are mandatory, and
will lead to errors if omitted. The mandatory tags vary depending
on the package type.

While packaging, the builder uses a temporary location named by the
value of the $PACKAGEROOT variable - the package sources are copied
there before packaging.

Packaging example:

env = Environment(tools=["default", "packaging"])
env.Install("/bin/", "my_program")
env.Package(
NAME="foo",
VERSION="1.2.3",
PACKAGEVERSION=0,
PACKAGETYPE="rpm",
LICENSE="gpl",
SUMMARY="balalalalal",
DESCRIPTION="this should be really really long",
X_RPM_GROUP="Application/fu",
SOURCE_URL="https://foo.org/foo-1.2.3.tar.gz",
)

In this example, the target /bin/my_program created by the Install
call would not be built by default since it is not under the
project top directory. However, since no source is specified to the
Package builder, it is selected for packaging by the default
sources rule. Since packaging is done using $PACKAGEROOT, no write
is actually done to the system's /bin directory, and the target
will be selected since after rebasing to underneath $PACKAGEROOT it
is now under the top directory of the project.

PCH(), env.PCH()
Builds a Microsoft Visual C++ precompiled header. Calling this
builder returns a list of two targets: the PCH as the first
element, and the object file as the second element. Normally the
object file is ignored. This builder is only provided when
Microsoft Visual C++ is being used as the compiler. The PCH builder
is generally used in conjunction with the $PCH construction
variable to force object files to use the precompiled header:

env['PCH'] = env.PCH('StdAfx.cpp')[0]

PDF(), env.PDF()
Builds a .pdf file from a .dvi input file (or, by extension, a
.tex, .ltx, or .latex input file). The suffix specified by the
$PDFSUFFIX construction variable (.pdf by default) is added
automatically to the target if it is not already present. Example:

# builds from aaa.tex
env.PDF(target = 'aaa.pdf', source = 'aaa.tex')
# builds bbb.pdf from bbb.dvi
env.PDF(target = 'bbb', source = 'bbb.dvi')

POInit(), env.POInit()
This builder belongs to msginit tool. The builder initializes
missing PO file(s) if $POAUTOINIT is set. If $POAUTOINIT is not set
(default), POInit prints instruction for user (that is supposed to
be a translator), telling how the PO file should be initialized. In
normal projects you should not use POInit and use POUpdate instead.
POUpdate chooses intelligently between msgmerge(1) and msginit(1).
POInit always uses msginit(1) and should be regarded as builder for
special purposes or for temporary use (e.g. for quick, one time
initialization of a bunch of PO files) or for tests.

Target nodes defined through POInit are not built by default
(they're Ignored from '.' node) but are added to special Alias
('po-create' by default). The alias name may be changed through the
$POCREATE_ALIAS construction variable. All PO files defined through
POInit may be easily initialized by scons po-create.

Example 1. Initialize en.po and pl.po from messages.pot:

# ...
env.POInit(['en', 'pl']) # messages.pot --> [en.po, pl.po]

Example 2. Initialize en.po and pl.po from foo.pot:

# ...
env.POInit(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.po]

Example 3. Initialize en.po and pl.po from foo.pot but using
$POTDOMAIN construction variable:

# ...
env.POInit(['en', 'pl'], POTDOMAIN='foo') # foo.pot --> [en.po, pl.po]

Example 4. Initialize PO files for languages defined in LINGUAS
file. The files will be initialized from template messages.pot:

# ...
env.POInit(LINGUAS_FILE = 1) # needs 'LINGUAS' file

Example 5. Initialize en.po and pl.pl PO files plus files for
languages defined in LINGUAS file. The files will be initialized
from template messages.pot:

# ...
env.POInit(['en', 'pl'], LINGUAS_FILE = 1)

Example 6. You may preconfigure your environment first, and then
initialize PO files:

# ...
env['POAUTOINIT'] = 1
env['LINGUAS_FILE'] = 1
env['POTDOMAIN'] = 'foo'
env.POInit()

which has same efect as:

# ...
env.POInit(POAUTOINIT = 1, LINGUAS_FILE = 1, POTDOMAIN = 'foo')

PostScript(), env.PostScript()
Builds a .ps file from a .dvi input file (or, by extension, a .tex,
.ltx, or .latex input file). The suffix specified by the $PSSUFFIX
construction variable (.ps by default) is added automatically to
the target if it is not already present. Example:

# builds from aaa.tex
env.PostScript(target = 'aaa.ps', source = 'aaa.tex')
# builds bbb.ps from bbb.dvi
env.PostScript(target = 'bbb', source = 'bbb.dvi')

POTUpdate(), env.POTUpdate()
The builder belongs to xgettext tool. The builder updates target
POT file if exists or creates one if it doesn't. The node is not
built by default (i.e. it is Ignored from '.'), but only on demand
(i.e. when given POT file is required or when special alias is
invoked). This builder adds its targe node (messages.pot, say) to a
special alias (pot-update by default, see $POTUPDATE_ALIAS) so you
can update/create them easily with scons pot-update. The file is
not written until there is no real change in internationalized
messages (or in comments that enter POT file).

Note
You may see xgettext(1) being invoked by the xgettext tool even
if there is no real change in internationalized messages (so
the POT file is not being updated). This happens every time a
source file has changed. In such case we invoke xgettext(1) and
compare its output with the content of POT file to decide
whether the file should be updated or not.

Example 1. Let's create po/ directory and place following
SConstruct script there:

# SConstruct in 'po/' subdir
env = Environment( tools = ['default', 'xgettext'] )
env.POTUpdate(['foo'], ['../a.cpp', '../b.cpp'])
env.POTUpdate(['bar'], ['../c.cpp', '../d.cpp'])

Then invoke scons few times:

user@host:$ scons # Does not create foo.pot nor bar.pot
user@host:$ scons foo.pot # Updates or creates foo.pot
user@host:$ scons pot-update # Updates or creates foo.pot and bar.pot
user@host:$ scons -c # Does not clean foo.pot nor bar.pot.

the results shall be as the comments above say.

Example 2. The POTUpdate builder may be used with no target
specified, in which case default target messages.pot will be used.
The default target may also be overridden by setting $POTDOMAIN
construction variable or providing it as an override to POTUpdate
builder:

# SConstruct script
env = Environment( tools = ['default', 'xgettext'] )
env['POTDOMAIN'] = "foo"
env.POTUpdate(source = ["a.cpp", "b.cpp"]) # Creates foo.pot ...
env.POTUpdate(POTDOMAIN = "bar", source = ["c.cpp", "d.cpp"]) # and bar.pot

Example 3. The sources may be specified within separate file, for
example POTFILES.in:

# POTFILES.in in 'po/' subdirectory
../a.cpp
../b.cpp
# end of file

The name of the file (POTFILES.in) containing the list of sources
is provided via $XGETTEXTFROM:

# SConstruct file in 'po/' subdirectory
env = Environment( tools = ['default', 'xgettext'] )
env.POTUpdate(XGETTEXTFROM = 'POTFILES.in')

Example 4. You may use $XGETTEXTPATH to define source search path.
Assume, for example, that you have files a.cpp, b.cpp,
po/SConstruct, po/POTFILES.in. Then your POT-related files could
look as below:

# POTFILES.in in 'po/' subdirectory
a.cpp
b.cpp
# end of file

# SConstruct file in 'po/' subdirectory
env = Environment( tools = ['default', 'xgettext'] )
env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH='../')

Example 5. Multiple search directories may be defined within a
list, i.e. XGETTEXTPATH = ['dir1', 'dir2', ...]. The order in the
list determines the search order of source files. The path to the
first file found is used.

Let's create 0/1/po/SConstruct script:

# SConstruct file in '0/1/po/' subdirectory
env = Environment( tools = ['default', 'xgettext'] )
env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../', '../../'])

and 0/1/po/POTFILES.in:

# POTFILES.in in '0/1/po/' subdirectory
a.cpp
# end of file

Write two *.cpp files, the first one is 0/a.cpp:

/* 0/a.cpp */
gettext("Hello from ../../a.cpp")

and the second is 0/1/a.cpp:

/* 0/1/a.cpp */
gettext("Hello from ../a.cpp")

then run scons. You'll obtain 0/1/po/messages.pot with the message
"Hello from ../a.cpp". When you reverse order in $XGETTEXTFOM, i.e.
when you write SConscript as

# SConstruct file in '0/1/po/' subdirectory
env = Environment( tools = ['default', 'xgettext'] )
env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../../', '../'])

then the messages.pot will contain msgid "Hello from ../../a.cpp"
line and not msgid "Hello from ../a.cpp".

POUpdate(), env.POUpdate()
The builder belongs to msgmerge tool. The builder updates PO files
with msgmerge(1), or initializes missing PO files as described in
documentation of msginit tool and POInit builder (see also
$POAUTOINIT). Note, that POUpdate does not add its targets to
po-create alias as POInit does.

Target nodes defined through POUpdate are not built by default
(they're Ignored from '.' node). Instead, they are added
automatically to special Alias ('po-update' by default). The alias
name may be changed through the $POUPDATE_ALIAS construction
variable. You can easily update PO files in your project by scons
po-update.

Example 1. Update en.po and pl.po from messages.pot template (see
also $POTDOMAIN), assuming that the later one exists or there is
rule to build it (see POTUpdate):

# ...
env.POUpdate(['en','pl']) # messages.pot --> [en.po, pl.po]

Example 2. Update en.po and pl.po from foo.pot template:

# ...
env.POUpdate(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.pl]

Example 3. Update en.po and pl.po from foo.pot (another version):

# ...
env.POUpdate(['en', 'pl'], POTDOMAIN='foo') # foo.pot -- > [en.po, pl.pl]

Example 4. Update files for languages defined in LINGUAS file. The
files are updated from messages.pot template:

# ...
env.POUpdate(LINGUAS_FILE = 1) # needs 'LINGUAS' file

Example 5. Same as above, but update from foo.pot template:

# ...
env.POUpdate(LINGUAS_FILE = 1, source = ['foo'])

Example 6. Update en.po and pl.po plus files for languages defined
in LINGUAS file. The files are updated from messages.pot template:

# produce 'en.po', 'pl.po' + files defined in 'LINGUAS':
env.POUpdate(['en', 'pl' ], LINGUAS_FILE = 1)

Example 7. Use $POAUTOINIT to automatically initialize PO file if
it doesn't exist:

# ...
env.POUpdate(LINGUAS_FILE = 1, POAUTOINIT = 1)

Example 8. Update PO files for languages defined in LINGUAS file.
The files are updated from foo.pot template. All necessary settings
are pre-configured via environment.

# ...
env['POAUTOINIT'] = 1
env['LINGUAS_FILE'] = 1
env['POTDOMAIN'] = 'foo'
env.POUpdate()

Program(), env.Program()
Builds an executable given one or more object files or C, C++, D,
or Fortran source files. If any C, C++, D or Fortran source files
are specified, then they will be automatically compiled to object
files using the Object builder method; see that builder method's
description for a list of legal source file suffixes and how they
are interpreted. The target executable file prefix, specified by
the $PROGPREFIX construction variable (nothing by default), and
suffix, specified by the $PROGSUFFIX construction variable (by
default, .exe on Windows systems, nothing on POSIX systems), are
automatically added to the target if not already present. Example:

env.Program(target='foo', source=['foo.o', 'bar.c', 'baz.f'])

ProgramAllAtOnce(), env.ProgramAllAtOnce()
Builds an executable from D sources without first creating
individual objects for each file.

D sources can be compiled file-by-file as C and C++ source are, and
D is integrated into the scons Object and Program builders for this
model of build. D codes can though do whole source meta-programming
(some of the testing frameworks do this). For this it is imperative
that all sources are compiled and linked in a single call to the D
compiler. This builder serves that purpose.

env.ProgramAllAtOnce('executable', ['mod_a.d, mod_b.d', 'mod_c.d'])

This command will compile the modules mod_a, mod_b, and mod_c in a
single compilation process without first creating object files for
the modules. Some of the D compilers will create executable.o
others will not.

RES(), env.RES()
Builds a Microsoft Visual C++ resource file. This builder method is
only provided when Microsoft Visual C++ or MinGW is being used as
the compiler. The .res (or .o for MinGW) suffix is added to the
target name if no other suffix is given. The source file is scanned
for implicit dependencies as though it were a C file. Example:

env.RES('resource.rc')

RMIC(), env.RMIC()
Builds stub and skeleton class files for remote objects from Java
.class files. The target is a directory relative to which the stub
and skeleton class files will be written. The source can be the
names of .class files, or the objects return from the Java builder
method.

If the construction variable $JAVACLASSDIR is set, either in the
environment or in the call to the RMIC builder method itself, then
the value of the variable will be stripped from the beginning of
any .class file names.

classes = env.Java(target = 'classdir', source = 'src')
env.RMIC(target = 'outdir1', source = classes)

env.RMIC(target = 'outdir2',
source = ['package/foo.class', 'package/bar.class'])

env.RMIC(target = 'outdir3',
source = ['classes/foo.class', 'classes/bar.class'],
JAVACLASSDIR = 'classes')

RPCGenClient(), env.RPCGenClient()
Generates an RPC client stub (_clnt.c) file from a specified RPC
(.x) source file. Because rpcgen only builds output files in the
local directory, the command will be executed in the source file's
directory by default.

# Builds src/rpcif_clnt.c
env.RPCGenClient('src/rpcif.x')

RPCGenHeader(), env.RPCGenHeader()
Generates an RPC header (.h) file from a specified RPC (.x) source
file. Because rpcgen only builds output files in the local
directory, the command will be executed in the source file's
directory by default.

# Builds src/rpcif.h
env.RPCGenHeader('src/rpcif.x')

RPCGenService(), env.RPCGenService()
Generates an RPC server-skeleton (_svc.c) file from a specified RPC
(.x) source file. Because rpcgen only builds output files in the
local directory, the command will be executed in the source file's
directory by default.

# Builds src/rpcif_svc.c
env.RPCGenClient('src/rpcif.x')

RPCGenXDR(), env.RPCGenXDR()
Generates an RPC XDR routine (_xdr.c) file from a specified RPC
(.x) source file. Because rpcgen only builds output files in the
local directory, the command will be executed in the source file's
directory by default.

# Builds src/rpcif_xdr.c
env.RPCGenClient('src/rpcif.x')

SharedLibrary(), env.SharedLibrary()
Builds a shared library (.so on a POSIX system, .dll on Windows)
given one or more object files or C, C++, D or Fortran source
files. If any source files are given, then they will be
automatically compiled to object files. The target library file
prefix, specified by the $SHLIBPREFIX construction variable (by
default, lib on POSIX systems, nothing on Windows systems), and
suffix, specified by the $SHLIBSUFFIX construction variable (by
default, .dll on Windows systems, .so on POSIX systems), are
automatically added to the target if not already present. Example:

env.SharedLibrary(target='bar', source=['bar.c', 'foo.o'])

On Windows systems, the SharedLibrary builder method will always
build an import library (.lib) in addition to the shared library
(.dll), adding a .lib library with the same basename if there is
not already a .lib file explicitly listed in the targets.

On Cygwin systems, the SharedLibrary builder method will always
build an import library (.dll.a) in addition to the shared library
(.dll), adding a .dll.a library with the same basename if there is
not already a .dll.a file explicitly listed in the targets.

Any object files listed in the source must have been built for a
shared library (that is, using the SharedObject builder method).
scons will raise an error if there is any mismatch.

On some platforms, there is a distinction between a shared library
(loaded automatically by the system to resolve external references)
and a loadable module (explicitly loaded by user action). For
maximum portability, use the LoadableModule builder for the latter.

When the $SHLIBVERSION construction variable is defined, a
versioned shared library is created. This modifies $SHLINKFLAGS as
required, adds the version number to the library name, and creates
any symbolic links that are needed.

env.SharedLibrary(target='bar', source=['bar.c', 'foo.o'], SHLIBVERSION='1.5.2')

On a POSIX system, versions with a single token create exactly one
symlink: libbar.so.6 would have symlink libbar.so only. On a POSIX
system, versions with two or more tokens create exactly two
symlinks: libbar.so.2.3.1 would have symlinks libbar.so and
libbar.so.2; on a Darwin (OSX) system the library would be
libbar.2.3.1.dylib and the link would be libbar.dylib.

On Windows systems, specifying register=1 will cause the .dll to be
registered after it is built. The command that is run is determined
by the $REGSVR construction variable (regsvr32 by default), and the
flags passed are determined by $REGSVRFLAGS. By default,
$REGSVRFLAGS includes the /s option, to prevent dialogs from
popping up and requiring user attention when it is run. If you
change $REGSVRFLAGS, be sure to include the /s option. For example,

env.SharedLibrary(target='bar', source=['bar.cxx', 'foo.obj'], register=1)

will register bar.dll as a COM object when it is done linking it.

SharedObject(), env.SharedObject()
Builds an object file intended for inclusion in a shared library.
Source files must have one of the same set of extensions specified
above for the StaticObject builder method. On some platforms
building a shared object requires additional compiler option (e.g.
-fPIC for gcc) in addition to those needed to build a normal
(static) object, but on some platforms there is no difference
between a shared object and a normal (static) one. When there is a
difference, SCons will only allow shared objects to be linked into
a shared library, and will use a different suffix for shared
objects. On platforms where there is no difference, SCons will
allow both normal (static) and shared objects to be linked into a
shared library, and will use the same suffix for shared and normal
(static) objects. The target object file prefix, specified by the
$SHOBJPREFIX construction variable (by default, the same as
$OBJPREFIX), and suffix, specified by the $SHOBJSUFFIX construction
variable, are automatically added to the target if not already
present. Examples:

env.SharedObject(target='ddd', source='ddd.c')
env.SharedObject(target='eee.o', source='eee.cpp')
env.SharedObject(target='fff.obj', source='fff.for')

Note that the source files will be scanned according to the suffix
mappings in the SourceFileScanner object. See the manpage section
"Scanner Objects" for more information.

StaticLibrary(), env.StaticLibrary()
Builds a static library given one or more object files or C, C++, D
or Fortran source files. If any source files are given, then they
will be automatically compiled to object files. The static library
file prefix, specified by the $LIBPREFIX construction variable (by
default, lib on POSIX systems, nothing on Windows systems), and
suffix, specified by the $LIBSUFFIX construction variable (by
default, .lib on Windows systems, .a on POSIX systems), are
automatically added to the target if not already present. Example:

env.StaticLibrary(target='bar', source=['bar.c', 'foo.o'])

Any object files listed in the source must have been built for a
static library (that is, using the StaticObject builder method).
scons will raise an error if there is any mismatch.

StaticObject(), env.StaticObject()
Builds a static object file from one or more C, C++, D, or Fortran
source files. Source files must have one of the following
extensions:

.asm assembly language file
.ASM assembly language file
.c C file
.C Windows: C file
POSIX: C++ file
.cc C++ file
.cpp C++ file
.cxx C++ file
.cxx C++ file
.c++ C++ file
.C++ C++ file
.d D file
.f Fortran file
.F Windows: Fortran file
POSIX: Fortran file + C pre-processor
.for Fortran file
.FOR Fortran file
.fpp Fortran file + C pre-processor
.FPP Fortran file + C pre-processor
.m Object C file
.mm Object C++ file
.s assembly language file
.S Windows: assembly language file
ARM: CodeSourcery Sourcery Lite
.sx assembly language file + C pre-processor
POSIX: assembly language file + C pre-processor
.spp assembly language file + C pre-processor
.SPP assembly language file + C pre-processor

The target object file prefix, specified by the $OBJPREFIX
construction variable (nothing by default), and suffix, specified
by the $OBJSUFFIX construction variable (.obj on Windows systems,
.o on POSIX systems), are automatically added to the target if not
already present. Examples:

env.StaticObject(target='aaa', source='aaa.c')
env.StaticObject(target='bbb.o', source='bbb.c++')
env.StaticObject(target='ccc.obj', source='ccc.f')

Note that the source files will be scanned according to the suffix
mappings in the SourceFileScanner object. See the manpage section
"Scanner Objects" for more information.

Substfile(), env.Substfile()
The Substfile builder creates a single text file from a template
consisting of a file or set of files (or nodes), replacing text
using the $SUBST_DICT construction variable (if set). If a set,
they are concatenated into the target file using the value of the
$LINESEPARATOR construction variable as a separator between
contents; the separator is not emitted after the contents of the
last file. Nested lists of source files are flattened. See also
Textfile.

If a single source file name is specified and has a .in suffix, the
suffix is stripped and the remainder of the name is used as the
default target name.

The prefix and suffix specified by the $SUBSTFILEPREFIX and
$SUBSTFILESUFFIX construction variables (an empty string by default
in both cases) are automatically added to the target if they are
not already present.

If a construction variable named $SUBST_DICT is present, it may be
either a Python dictionary or a sequence of (key, value) tuples. If
it is a dictionary it is converted into a list of tuples with
unspecified order, so if one key is a prefix of another key or if
one substitution could be further expanded by another subsitition,
it is unpredictable whether the expansion will occur.

Any occurrences of a key in the source are replaced by the
corresponding value, which may be a Python callable function or a
string. If the value is a callable, it is called with no arguments
to get a string. Strings are subst-expanded and the result replaces
the key.

env = Environment(tools=['default'])

env['prefix'] = '/usr/bin'
script_dict = {'@prefix@': '/bin', '@exec_prefix@': '$prefix'}
env.Substfile('script.in', SUBST_DICT=script_dict)

conf_dict = {'%VERSION%': '1.2.3', '%BASE%': 'MyProg'}
env.Substfile('config.h.in', conf_dict, SUBST_DICT=conf_dict)

# UNPREDICTABLE - one key is a prefix of another
bad_foo = {'$foo': '$foo', '$foobar': '$foobar'}
env.Substfile('foo.in', SUBST_DICT=bad_foo)

# PREDICTABLE - keys are applied longest first
good_foo = [('$foobar', '$foobar'), ('$foo', '$foo')]
env.Substfile('foo.in', SUBST_DICT=good_foo)

# UNPREDICTABLE - one substitution could be futher expanded
bad_bar = {'@bar@': '@soap@', '@soap@': 'lye'}
env.Substfile('bar.in', SUBST_DICT=bad_bar)

# PREDICTABLE - substitutions are expanded in order
good_bar = (('@bar@', '@soap@'), ('@soap@', 'lye'))
env.Substfile('bar.in', SUBST_DICT=good_bar)

# the SUBST_DICT may be in common (and not an override)
substutions = {}
subst = Environment(tools=['textfile'], SUBST_DICT=substitutions)
substitutions['@foo@'] = 'foo'
subst['SUBST_DICT']['@bar@'] = 'bar'
subst.Substfile(
'pgm1.c',
[Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm1.in"],
)
subst.Substfile(
'pgm2.c',
[Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm2.in"],
)

Tar(), env.Tar()
Builds a tar archive of the specified files and/or directories.
Unlike most builder methods, the Tar builder method may be called
multiple times for a given target; each additional call adds to the
list of entries that will be built into the archive. Any source
directories will be scanned for changes to any on-disk files,
regardless of whether or not scons knows about them from other
Builder or function calls.

env.Tar('src.tar', 'src')

# Create the stuff.tar file.
env.Tar('stuff', ['subdir1', 'subdir2'])
# Also add "another" to the stuff.tar file.
env.Tar('stuff', 'another')

# Set TARFLAGS to create a gzip-filtered archive.
env = Environment(TARFLAGS = '-c -z')
env.Tar('foo.tar.gz', 'foo')

# Also set the suffix to .tgz.
env = Environment(TARFLAGS = '-c -z',
TARSUFFIX = '.tgz')
env.Tar('foo')

Textfile(), env.Textfile()
The Textfile builder generates a single text file from a template
consisting of a list of strings, replacing text using the
$SUBST_DICT construction variable (if set) - see Substfile for a
description of replacement. The strings will be separated in the
target file using the value of the $LINESEPARATOR construction
variable; the line separator is not emitted after the last string.
Nested lists of source strings are flattened. Source strings need
not literally be Python strings: they can be Nodes or Python
objects that convert cleanly to Value nodes

The prefix and suffix specified by the $TEXTFILEPREFIX and
$TEXTFILESUFFIX construction variables (by default an empty string
and .txt, respectively) are automatically added to the target if
they are not already present. Examples:

# builds/writes foo.txt
env.Textfile(target='foo.txt', source=['Goethe', 42, 'Schiller'])

# builds/writes bar.txt
env.Textfile(target='bar', source=['lalala', 'tanteratei'], LINESEPARATOR='|*')

# nested lists are flattened automatically
env.Textfile(target='blob', source=['lalala', ['Goethe', 42, 'Schiller'], 'tanteratei'])

# files may be used as input by wraping them in File()
env.Textfile(
target='concat', # concatenate files with a marker between
source=[File('concat1'), File('concat2')],
LINESEPARATOR='====================\n',
)

Results:

foo.txt

Goethe
42
Schiller

bar.txt

lalala|*tanteratei

blob.txt

lalala
Goethe
42
Schiller
tanteratei

Translate(), env.Translate()
This pseudo-builder belongs to gettext toolset. The builder
extracts internationalized messages from source files, updates POT
template (if necessary) and then updates PO translations (if
necessary). If $POAUTOINIT is set, missing PO files will be
automatically created (i.e. without translator person
intervention). The variables $LINGUAS_FILE and $POTDOMAIN are taken
into acount too. All other construction variables used by
POTUpdate, and POUpdate work here too.

Example 1. The simplest way is to specify input files and output
languages inline in a SCons script when invoking Translate

# SConscript in 'po/' directory
env = Environment( tools = ["default", "gettext"] )
env['POAUTOINIT'] = 1
env.Translate(['en','pl'], ['../a.cpp','../b.cpp'])

Example 2. If you wish, you may also stick to conventional style
known from autotools, i.e. using POTFILES.in and LINGUAS files

# LINGUAS
en pl
#end

# POTFILES.in
a.cpp
b.cpp
# end

# SConscript
env = Environment( tools = ["default", "gettext"] )
env['POAUTOINIT'] = 1
env['XGETTEXTPATH'] = ['../']
env.Translate(LINGUAS_FILE = 1, XGETTEXTFROM = 'POTFILES.in')

The last approach is perhaps the recommended one. It allows easily
split internationalization/localization onto separate SCons
scripts, where a script in source tree is responsible for
translations (from sources to PO files) and script(s) under variant
directories are responsible for compilation of PO to MO files to
and for installation of MO files. The "gluing factor" synchronizing
these two scripts is then the content of LINGUAS file. Note, that
the updated POT and PO files are usually going to be committed back
to the repository, so they must be updated within the source
directory (and not in variant directories). Additionaly, the file
listing of po/ directory contains LINGUAS file, so the source tree
looks familiar to translators, and they may work with the project
in their usual way.

Example 3. Let's prepare a development tree as below

project/
+ SConstruct
+ build/
+ src/
+ po/
+ SConscript
+ SConscript.i18n
+ POTFILES.in
+ LINGUAS

with build being variant directory. Write the top-level SConstruct
script as follows

# SConstruct
env = Environment( tools = ["default", "gettext"] )
VariantDir('build', 'src', duplicate = 0)
env['POAUTOINIT'] = 1
SConscript('src/po/SConscript.i18n', exports = 'env')
SConscript('build/po/SConscript', exports = 'env')

the src/po/SConscript.i18n as

# src/po/SConscript.i18n
Import('env')
env.Translate(LINGUAS_FILE=1, XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../'])

and the src/po/SConscript

# src/po/SConscript
Import('env')
env.MOFiles(LINGUAS_FILE = 1)

Such setup produces POT and PO files under source tree in src/po/
and binary MO files under variant tree in build/po/. This way the
POT and PO files are separated from other output files, which must
not be committed back to source repositories (e.g. MO files).

Note
In above example, the PO files are not updated, nor created
automatically when you issue scons '.' command. The files must
be updated (created) by hand via scons po-update and then MO
files can be compiled by running scons '.'.

TypeLibrary(), env.TypeLibrary()
Builds a Windows type library (.tlb) file from an input IDL file
(.idl). In addition, it will build the associated interface stub
and proxy source files, naming them according to the base name of
the .idl file. For example,

env.TypeLibrary(source="foo.idl")

Will create foo.tlb, foo.h, foo_i.c, foo_p.c and foo_data.c files.

Uic(), env.Uic()
Builds a header file, an implementation file and a moc file from an
ui file. and returns the corresponding nodes in the that order.
This builder is only available after using the tool qt. Note: you
can specify .ui files directly as source files to the Program,
Library and SharedLibrary builders without using this builder.
Using this builder lets you override the standard naming
conventions (be careful: prefixes are always prepended to names of
built files; if you don't want prefixes, you may set them to ``).
See the $QTDIR variable for more information. Example:

env.Uic('foo.ui') # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc']
env.Uic(
target=Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'),
source='foo.ui'
) # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']

Zip(), env.Zip()
Builds a zip archive of the specified files and/or directories.
Unlike most builder methods, the Zip builder method may be called
multiple times for a given target; each additional call adds to the
list of entries that will be built into the archive. Any source
directories will be scanned for changes to any on-disk files,
regardless of whether or not scons knows about them from other
Builder or function calls.

env.Zip('src.zip', 'src')

# Create the stuff.zip file.
env.Zip('stuff', ['subdir1', 'subdir2'])
# Also add "another" to the stuff.tar file.
env.Zip('stuff', 'another')

All targets of builder methods automatically depend on their sources.
An explicit dependency can be specified using the env.Depends method of
a construction environment (see below).

In addition, scons automatically scans source files for various
programming languages, so the dependencies do not need to be specified
explicitly. By default, SCons can C source files, C++ source files,
Fortran source files with .F (POSIX systems only), .fpp, or .FPP file
extensions, and assembly language files with .S (POSIX systems only),
.spp, or .SPP files extensions for C preprocessor dependencies. SCons
also has default support for scanning D source files, You can also
write your own Scanners to add support for additional source file
types. These can be added to the default Scanner object used by the
Object, StaticObject and SharedObject Builders by adding them to the
SourceFileScanner object. See the section called “Scanner Objects” for
more information about defining your own Scanner objects and using the
SourceFileScanner object.

Methods and Functions To Do Things
In addition to Builder methods, scons provides a number of other
construction environment methods and global functions to manipulate the
build configuration.

Usually, a construction environment method and global function with the
same name both exist for convenience. In the following list, the global
function is documented in this style:

Function(arguments, [optional arguments])

and the construction environment method looks like:

env.Function(arguments, [optional arguments])

If the function can be called both ways, then both forms are listed.

The global function and same-named construction environment method
provide almost identical functionality, with a couple of exceptions.
First, many of the construction environment methods affect only that
construction environment, while the global function has a global
effect. Second, where appropriate, calling the functionality through a
construction environment will substitute construction variables into
any supplied string arguments, while the global function doesn't have
the context of a construction environment to pick variables from, so it
cannot perform the substitution. For example:

Default('$FOO')

env = Environment(FOO='foo')
env.Default('$FOO')

In the above example, the call to the global Default function will add
a target named $FOO to the list of default targets, while the call to
the env.Default construction environment method will expand the value
and add a target named foo to the list of default targets. For more on
construction variable expansion, see the next section on construction
variables.

Global functions may be called from custom Python modules that you
import into an SConscript file by adding the following import to the
Python module:

from SCons.Script import *

Construction environment methods and global functions provided by scons
include:

Action(action, [output, [var, ...]] [key=value, ...]),
env.Action(action, [output, [var, ...]] [key=value, ...])
A factory function to create an Action object for the specified
action. See the manpage section "Action Objects" for a complete
explanation of the arguments and behavior.

Note that the env.Action form of the invocation will expand
construction variables in any argument strings, including the
action argument, at the time it is called using the construction
variables in the env construction environment through which
env.Action was called. The Action global function form delays all
variable expansion until the Action object is actually used.

AddMethod(object, function, [name]), env.AddMethod(function, [name])
Adds function to an object as a method. function will be called
with an instance object as the first argument as for other methods.
If name is given, it is used as the name of the new method, else
the name of function is used.

When the global function AddMethod is called, the object to add the
method to must be passed as the first argument; typically this will
be Environment, in order to create a method which applies to all
construction environments subsequently constructed. When called
using the env.AddMethod form, the method is added to the specified
construction environment only. Added methods propagate through
env.Clone calls.

More examples:

# Function to add must accept an instance argument.
# The Python convention is to call this 'self'.
def my_method(self, arg):
print("my_method() got", arg)

# Use the global function to add a method to the Environment class:
AddMethod(Environment, my_method)
env = Environment()
env.my_method('arg')

# Use the optional name argument to set the name of the method:
env.AddMethod(my_method, 'other_method_name')
env.other_method_name('another arg')

AddOption(arguments)
Adds a local (project-specific) command-line option. arguments are
the same as those supported by the add_option method in the
standard Python library module optparse, with a few additional
capabilities noted below. See the documentation for optparse for a
thorough discussion of its option-processing capabities.

In addition to the arguments and values supported by the optparse
add_option method, AddOption allows setting the nargs keyword value
to a string consisting of a question mark ('?') to indicate that
the option argument for that option string is optional. If the
option string is present on the command line but has no matching
option argument, the value of the const keyword argument is
produced as the value of the option. If the option string is
omitted from the command line, the value of the default keyword
argument is produced, as usual; if there is no default keyword
argument in the AddOption call, None is produced.

optparse recognizes abbreviations of long option names, as long as
they can be unambiguously resolved. For example, if add_option is
called to define a --devicename option, it will recognize --device,
--dev and so forth as long as there is no other option which could
also match to the same abbreviation. Options added via AddOption do
not support the automatic recognition of abbreviations. Instead, to
allow specific abbreviations, include them as synonyms in the
AddOption call itself.

Once a new command-line option has been added with AddOption, the
option value may be accessed using GetOption or env.GetOption.
SetOption is not currently supported for options added with
AddOption.

Help text for an option is a combination of the string supplied in
the help keyword argument to AddOption and information collected
from the other keyword arguments. Such help is displayed if the -h
command line option is used (but not with -H). Help for all local
options is displayed under the separate heading Local Options. The
options are unsorted - they will appear in the help text in the
order in which the AddOption calls occur.

Example:

AddOption(
'--prefix',
dest='prefix',
nargs=1,
type='string',
action='store',
metavar='DIR',
help='installation prefix',
)
env = Environment(PREFIX=GetOption('prefix'))

For that example, the following help text would be produced:

Local Options:
--prefix=DIR installation prefix

Help text for local options may be unavailable if the Help function
has been called, see the Help documentation for details.

Note
As an artifact of the internal implementation, the behavior of
options added by AddOption which take option arguments is
undefined if whitespace (rather than an = sign) is used as the
separator on the command line. Users should avoid such usage;
it is recommended to add a note to this effect to project
documentation if the situation is likely to arise. In addition,
if the nargs keyword is used to specify more than one following
option argument (that is, with a value of 2 or greater), such
arguments would necessarily be whitespace separated, triggering
the issue. Developers should not use AddOption this way. Future
versions of SCons will likely forbid such usage.

AddPostAction(target, action), env.AddPostAction(target, action)
Arranges for the specified action to be performed after the
specified target has been built. The specified action(s) may be an
Action object, or anything that can be converted into an Action
object See the manpage section "Action Objects" for a complete
explanation.

When multiple targets are supplied, the action may be called
multiple times, once after each action that generates one or more
targets in the list.

AddPreAction(target, action), env.AddPreAction(target, action)
Arranges for the specified action to be performed before the
specified target is built. The specified action(s) may be an Action
object, or anything that can be converted into an Action object See
the manpage section "Action Objects" for a complete explanation.

When multiple targets are specified, the action(s) may be called
multiple times, once before each action that generates one or more
targets in the list.

Note that if any of the targets are built in multiple steps, the
action will be invoked just before the "final" action that
specifically generates the specified target(s). For example, when
building an executable program from a specified source .c file via
an intermediate object file:

foo = Program('foo.c')
AddPreAction(foo, 'pre_action')

The specified pre_action would be executed before scons calls the
link command that actually generates the executable program binary
foo, not before compiling the foo.c file into an object file.

Alias(alias, [targets, [action]]), env.Alias(alias, [targets,
[action]])
Creates one or more phony targets that expand to one or more other
targets. An optional action (command) or list of actions can be
specified that will be executed whenever the any of the alias
targets are out-of-date. Returns the Node object representing the
alias, which exists outside of any file system. This Node object,
or the alias name, may be used as a dependency of any other target,
including another alias. Alias can be called multiple times for
the same alias to add additional targets to the alias, or
additional actions to the list for this alias. Aliases are global
even if set through the construction environment method.

Examples:

Alias('install')
Alias('install', '/usr/bin')
Alias(['install', 'install-lib'], '/usr/local/lib')

env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
env.Alias('install', ['/usr/local/man'])

env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")

AllowSubstExceptions([exception, ...])
Specifies the exceptions that will be allowed when expanding
construction variables. By default, any construction variable
expansions that generate a NameError or IndexError exception will
expand to a '' (an empty string) and not cause scons to fail. All
exceptions not in the specified list will generate an error message
and terminate processing.

If AllowSubstExceptions is called multiple times, each call
completely overwrites the previous list of allowed exceptions.

Example:

# Requires that all construction variable names exist.
# (You may wish to do this if you want to enforce strictly
# that all construction variables must be defined before use.)
AllowSubstExceptions()

# Also allow a string containing a zero-division expansion
# like '${1 / 0}' to evalute to ''.
AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)

AlwaysBuild(target, ...), env.AlwaysBuild(target, ...)
Marks each given target so that it is always assumed to be out of
date, and will always be rebuilt if needed. Note, however, that
AlwaysBuild does not add its target(s) to the default target list,
so the targets will only be built if they are specified on the
command line, or are a dependent of a target specified on the
command line--but they will always be built if so specified.
Multiple targets can be passed in to a single call to AlwaysBuild.

env.Append(key=val, [...])
Intelligently append values to construction variables in the
construction environment named by env. The construction variables
and values to add to them are passed as key=val pairs (Python
keyword arguments). env.Append is designed to allow adding values
without normally having to know the data type of an existing
construction variable. Regular Python syntax can also be used to
manipulate the construction variable, but for that you must know
the type of the construction variable: for example, different
Python syntax is needed to combine a list of values with a single
string value, or vice versa. Some pre-defined construction
variables do have type expectations based on how SCons will use
them, for example $CPPDEFINES is normally a string or a list of
strings, but can be a string, a list of strings, a list of tuples,
or a dictionary, while $LIBEMITTER would expect a callable or list
of callables, and $BUILDERS would expect a mapping type. Consult
the documentation for the various construction variables for more
details.

The following descriptions apply to both the append and prepend
functions, the only difference being the insertion point of the
added values.

If env. does not have a construction variable indicated by key, val
is added to the environment under that key as-is.

val can be almost any type, and SCons will combine it with an
existing value into an appropriate type, but there are a few
special cases to be aware of. When two strings are combined, the
result is normally a new string, with the caller responsible for
supplying any needed separation. The exception to this is the
construction variable $CPPDEFINES, in which each item will be
postprocessed by adding a prefix and/or suffix, so the contents are
treated as a list of strings, that is, adding a string will result
in a separate string entry, not a combined string. For $CPPDEFINES
as well as for $LIBS, and the various *PATH; variables, SCons will
supply the compiler-specific syntax (e.g. adding a -D or /D prefix
for $CPPDEFINES), so this syntax should be omitted when adding
values to these variables. Example (gcc syntax shown in the
expansion of CPPDEFINES):

env = Environment(CXXFLAGS="-std=c11", CPPDEFINES="RELEASE")
print("CXXFLAGS={}, CPPDEFINES={}".format(env['CXXFLAGS'], env['CPPDEFINES']))
# notice including a leading space in CXXFLAGS value
env.Append(CXXFLAGS=" -O", CPPDEFINES="EXTRA")
print("CXXFLAGS={}, CPPDEFINES={}".format(env['CXXFLAGS'], env['CPPDEFINES']))
print("CPPDEFINES will expand to {}".format(env.subst("$_CPPDEFFLAGS")))

$ scons -Q
CXXFLAGS=-std=c11, CPPDEFINES=RELEASE
CXXFLAGS=-std=c11 -O, CPPDEFINES=['RELEASE', 'EXTRA']
CPPDEFINES will expand to -DRELEASE -DEXTRA
scons: `.' is up to date.

Because $CPPDEFINES is intended to describe C/C++ pre-processor
macro definitions, it accepts additional syntax. Preprocessor
macros can be valued, or un-valued, as in -DBAR=1 or -DFOO. The
macro can be be supplied as a complete string including the value,
or as a tuple (or list) of macro, value, or as a dictionary.
Example (again gcc syntax in the expanded defines):

env = Environment(CPPDEFINES="FOO")
print("CPPDEFINES={}".format(env['CPPDEFINES']))
env.Append(CPPDEFINES="BAR=1")
print("CPPDEFINES={}".format(env['CPPDEFINES']))
env.Append(CPPDEFINES=("OTHER", 2))
print("CPPDEFINES={}".format(env['CPPDEFINES']))
env.Append(CPPDEFINES={"EXTRA": "arg"})
print("CPPDEFINES={}".format(env['CPPDEFINES']))
print("CPPDEFINES will expand to {}".format(env.subst("$_CPPDEFFLAGS")))

$ scons -Q
CPPDEFINES=FOO
CPPDEFINES=['FOO', 'BAR=1']
CPPDEFINES=['FOO', 'BAR=1', ('OTHER', 2)]
CPPDEFINES=['FOO', 'BAR=1', ('OTHER', 2), {'EXTRA': 'arg'}]
CPPDEFINES will expand to -DFOO -DBAR=1 -DOTHER=2 -DEXTRA=arg
scons: `.' is up to date.

Adding a string val to a dictonary construction variable will enter
val as the key in the dict, and None as its value. Using a tuple
type to supply a key + value only works for the special case of
$CPPDEFINES described above.

Although most combinations of types work without needing to know
the details, some combinations do not make sense and a Python
exception will be raised.

When using env.Append to modify construction variables which are
path specifications (conventionally, the names of such end in
PATH), it is recommended to add the values as a list of strings,
even if there is only a single string to add. The same goes for
adding library names to $LIBS.

env.Append(CPPPATH=["#/include"])

See also env.AppendUnique, env.Prepend and env.PrependUnique.

env.AppendENVPath(name, newpath, [envname, sep, delete_existing=False])
Append path elements specified by newpath to the given search path
string or list name in mapping envname in the construction
environment. Supplying envname is optional: the default is the
execution environment $ENV. Optional sep is used as the search path
separator, the default is the platform's separator (os.pathsep). A
path element will only appear once. Any duplicates in newpath are
dropped, keeping the last appearing (to preserve path order). If
delete_existing is False (the default) any addition duplicating an
existing path element is ignored; if delete_existing is True the
existing value will be dropped and the path element will be added
at the end. To help maintain uniqueness all paths are normalized
(using os.path.normpath and os.path.normcase).

Example:

print('before:', env['ENV']['INCLUDE'])
include_path = '/foo/bar:/foo'
env.AppendENVPath('INCLUDE', include_path)
print('after:', env['ENV']['INCLUDE'])

Yields:

before: /foo:/biz
after: /biz:/foo/bar:/foo

See also env.AppendENVPath.

env.PrependUnique(key=val, delete_existing=False, [...])
Prepend values to construction variables in the current
construction environment, maintaining uniqueness. Works like
env.Append (see for details), except that values are added to the
front, rather than the end, of any existing value of the
construction variable, and values already present in the
construction variable will not be added again. If delete_existing
is True, the existing matching value is first removed, and the
requested value is inserted, having the effect of moving such
values to the front.

Example:

env.PrependUnique(CCFLAGS='-g', FOO=['foo.yyy'])

See also env.Append, env.AppendUnique and env.Prepend.

Progress(callable, [interval]), Progress(string, [interval, file,
overwrite]), Progress(list_of_strings, [interval, file, overwrite])
Allows SCons to show progress made during the build by displaying a
string or calling a function while evaluating Nodes (e.g. files).

If the first specified argument is a Python callable (a function or
an object that has a __call__ method), the function will be called
once every interval times a Node is evaluated (default 1). The
callable will be passed the evaluated Node as its only argument.
(For future compatibility, it's a good idea to also add *args and
**kwargs as arguments to your function or method signatures. This
will prevent the code from breaking if SCons ever changes the
interface to call the function with additional arguments in the
future.)

An example of a simple custom progress function that prints a
string containing the Node name every 10 Nodes:

def my_progress_function(node, *args, **kwargs):
print('Evaluating node %s!' % node)
Progress(my_progress_function, interval=10)

A more complicated example of a custom progress display object that
prints a string containing a count every 100 evaluated Nodes. Note
the use of \r (a carriage return) at the end so that the string
will overwrite itself on a display:

import sys
class ProgressCounter(object):
count = 0
def __call__(self, node, *args, **kw):
self.count += 100
sys.stderr.write('Evaluated %s nodes\r' % self.count)

Progress(ProgressCounter(), interval=100)

If the first argument to Progress is a string or list of strings,
it is taken as text to be displayed every interval evaluated Nodes.
If the first argument is a list of strings, then each string in the
list will be displayed in rotating fashion every interval evaluated
Nodes.

The default is to print the string on standard output. An alternate
output stream may be specified with the file keyword argument,
which the caller must pass already opened.

The following will print a series of dots on the error output, one
dot for every 100 evaluated Nodes:

import sys
Progress('.', interval=100, file=sys.stderr)

If the string contains the verbatim substring $TARGET;, it will be
replaced with the Node. Note that, for performance reasons, this is
not a regular SCons variable substition, so you can not use other
variables or use curly braces. The following example will print the
name of every evaluated Node, using a carriage return) (\r) to
cause each line to overwritten by the next line, and the overwrite
keyword argument (default False) to make sure the
previously-printed file name is overwritten with blank spaces:

import sys
Progress('$TARGET\r', overwrite=True)

A list of strings can be used to implement a "spinner" on the
user's screen as follows, changing every five evaluated Nodes:

Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)

Pseudo(target, ...), env.Pseudo(target, ...)
This indicates that each given target should not be created by the
build rule, and if the target is created, an error will be
generated. This is similar to the gnu make .PHONY target. However,
in the vast majority of cases, an Alias is more appropriate.
Multiple targets can be passed in to a single call to Pseudo.

PyPackageDir(modulename), env.PyPackageDir(modulename)
This returns a Directory Node similar to Dir. The python module /
package is looked up and if located the directory is returned for
the location. modulename Is a named python package / module to
lookup the directory for it's location.

If modulename is a list, SCons returns a list of Dir nodes.
Construction variables are expanded in modulename.

env.Replace(key=val, [...])
Replaces construction variables in the Environment with the
specified keyword arguments.

Example:

env.Replace(CCFLAGS='-g', FOO='foo.xxx')

Repository(directory), env.Repository(directory)
Specifies that directory is a repository to be searched for files.
Multiple calls to Repository are legal, and each one adds to the
list of repositories that will be searched.

To scons, a repository is a copy of the source tree, from the
top-level directory on down, which may contain both source files
and derived files that can be used to build targets in the local
source tree. The canonical example would be an official source tree
maintained by an integrator. If the repository contains derived
files, then the derived files should have been built using scons,
so that the repository contains the necessary signature information
to allow scons to figure out when it is appropriate to use the
repository copy of a derived file, instead of building one locally.

Note that if an up-to-date derived file already exists in a
repository, scons will not make a copy in the local directory tree.
In order to guarantee that a local copy will be made, use the Local
method.

Requires(target, prerequisite), env.Requires(target, prerequisite)
Specifies an order-only relationship between the specified target
file(s) and the specified prerequisite file(s). The prerequisite
file(s) will be (re)built, if necessary, before the target file(s),
but the target file(s) do not actually depend on the prerequisites
and will not be rebuilt simply because the prerequisite file(s)
change.

Example:

env.Requires('foo', 'file-that-must-be-built-before-foo')

Return([vars..., stop=True])
Return to the calling SConscript, optionally returning the values
of variables named in vars. Multiple strings contaning variable
names may be passed to Return. A string containing white space is
split into individual variable names. Returns the value if one
variable is specified, else returns a tuple of values. Returns an
empty tuple if vars is omitted.

By default Return stops processing the current SConscript and
returns immediately. The optional stop keyword argument may be set
to a false value to continue processing the rest of the SConscript
file after the Return call (this was the default behavior prior to
SCons 0.98.) However, the values returned are still the values of
the variables in the named vars at the point Return was called.

Examples:

# Returns no values (evaluates False)
Return()

# Returns the value of the 'foo' Python variable.
Return("foo")

# Returns the values of the Python variables 'foo' and 'bar'.
Return("foo", "bar")

# Returns the values of Python variables 'val1' and 'val2'.
Return('val1 val2')

Scanner(function, [name, argument, skeys, path_function, node_class,
node_factory, scan_check, recursive]), env.Scanner(function, [name,
argument, skeys, path_function, node_class, node_factory, scan_check,
recursive])
Creates a Scanner object for the specified function. See manpage
section "Scanner Objects" for a complete explanation of the
arguments and behavior.

SConscript(scripts, [exports, variant_dir, duplicate, must_exist]),
env.SConscript(scripts, [exports, variant_dir, duplicate, must_exist]),
SConscript(dirs=subdirs, [name=scriptname, exports, variant_dir,
duplicate, must_exist]), env.SConscript(dirs=subdirs, [name=scriptname,
exports, variant_dir, duplicate, must_exist])
Executes one or more subsidiary SConscript (configuration) files.
There are two ways to call the SConscript function.

The first calling style is to supply one or more SConscript file
names as the first (positional) argument. A single script may be
specified as a string; multiple scripts must be specified as a list
of strings (either explicitly or as created by a function like
Split). Examples:

SConscript('SConscript') # run SConscript in the current directory
SConscript('src/SConscript') # run SConscript in the src directory
SConscript(['src/SConscript', 'doc/SConscript'])
config = SConscript('MyConfig.py')

The other calling style is to omit the positional argument naming
scripts and instead specify a list of directory names using the
dirs keyword argument. In this case, scons will execute a
subsidiary configuration file named SConscript in each of the
specified directories. You may specify a name other than SConscript
by supplying an optional name=scriptname keyword argument. The
first three examples below have the same effect as the first three
examples above:

SConscript(dirs='.') # run SConscript in the current directory
SConscript(dirs='src') # run SConscript in the src directory
SConscript(dirs=['src', 'doc'])
SConscript(dirs=['sub1', 'sub2'], name='MySConscript')

The optional exports keyword argument provides a string or list of
strings representing variable names, or a dictionary of named
values, to export. For the first calling style only, a second
positional argument will be interpreted as exports; the second
calling style must use the keyword argument form for exports. These
variables are locally exported only to the called SConscript
file(s) and do not affect the global pool of variables managed by
the Export function. The subsidiary SConscript files must use the
Import function to import the variables. Examples:

foo = SConscript('sub/SConscript', exports='env')
SConscript('dir/SConscript', exports=['env', 'variable'])
SConscript(dirs='subdir', exports='env variable')
SConscript(dirs=['one', 'two', 'three'], exports='shared_info')

If the optional variant_dir argument is present, it causes an
effect equivalent to the VariantDir function, but in effect only
within the scope of the SConscript call. The variant_dir argument
is interpreted relative to the directory of the calling SConscript
file. The source directory is the directory in which the called
SConscript file resides and the SConscript file is evaluated as if
it were in the variant_dir directory. Thus:

SConscript('src/SConscript', variant_dir='build')

is equivalent to:

VariantDir('build', 'src')
SConscript('build/SConscript')

If the sources are in the same directory as the SConstruct,

SConscript('SConscript', variant_dir='build')

is equivalent to:

VariantDir('build', '.')
SConscript('build/SConscript')

The optional duplicate argument is interpreted as for VariantDir.
If the variant_dir argument is omitted, the duplicate argument is
ignored. See the description of VariantDir for additional details
and restrictions.

If the optional must_exist is True, causes an exception to be
raised if a requested SConscript file is not found. The current
default is False, causing only a warning to be emitted, but this
default is deprecated (since 3.1). For scripts which truly intend
to be optional, transition to explicitly supplying must_exist=False
to the SConscript call.

Here are some composite examples:

# collect the configuration information and use it to build src and doc
shared_info = SConscript('MyConfig.py')
SConscript('src/SConscript', exports='shared_info')
SConscript('doc/SConscript', exports='shared_info')

# build debugging and production versions. SConscript
# can use Dir('.').path to determine variant.
SConscript('SConscript', variant_dir='debug', duplicate=0)
SConscript('SConscript', variant_dir='prod', duplicate=0)

# build debugging and production versions. SConscript
# is passed flags to use.
opts = { 'CPPDEFINES' : ['DEBUG'], 'CCFLAGS' : '-pgdb' }
SConscript('SConscript', variant_dir='debug', duplicate=0, exports=opts)
opts = { 'CPPDEFINES' : ['NODEBUG'], 'CCFLAGS' : '-O' }
SConscript('SConscript', variant_dir='prod', duplicate=0, exports=opts)

# build common documentation and compile for different architectures
SConscript('doc/SConscript', variant_dir='build/doc', duplicate=0)
SConscript('src/SConscript', variant_dir='build/x86', duplicate=0)
SConscript('src/SConscript', variant_dir='build/ppc', duplicate=0)

SConscript returns the values of any variables named by the
executed SConscript file(s) in arguments to the Return function. If
a single SConscript call causes multiple scripts to be executed,
the return value is a tuple containing the returns of each of the
scripts. If an executed script does not explicitly call Return, it
returns None.

SConscriptChdir(value), env.SConscriptChdir(value)
By default, scons changes its working directory to the directory in
which each subsidiary SConscript file lives. This behavior may be
disabled by specifying either:

SConscriptChdir(0)
env.SConscriptChdir(0)

in which case scons will stay in the top-level directory while
reading all SConscript files. (This may be necessary when building
from repositories, when all the directories in which SConscript
files may be found don't necessarily exist locally.) You may enable
and disable this ability by calling SConscriptChdir multiple times.

Example:

env = Environment()
SConscriptChdir(0)
SConscript('foo/SConscript') # will not chdir to foo
env.SConscriptChdir(1)
SConscript('bar/SConscript') # will chdir to bar

SConsignFile([name, dbm_module]), env.SConsignFile([name, dbm_module])
Specify where to store the SCons file signature database, and which
database format to use. This may be useful to specify alternate
database files and/or file locations for different types of builds.

The optional name argument is the base name of the database
file(s). If not an absolute path name, these are placed relative to
the directory containing the top-level SConstruct file. The default
is .sconsign. The actual database file(s) stored on disk may have
an appropriate suffix appended by the chosen dbm_module

The optional dbm_module argument specifies which Python database
module to use for reading/writing the file. The module must be
imported first; then the imported module name is passed as the
argument. The default is a custom SCons.dblite module that uses
pickled Python data structures, which works on all Python versions.
See documentation of the Python dbm module for other available
types.

If called with no arguments, the database will default to
.sconsign.dblite in the top directory of the project, which is also
the default if if SConsignFile is not called.

The setting is global, so the only difference between the global
function and the environment method form is variable expansion on
name. There should only be one active call to this function/method
in a given build setup.

If name is set to None, scons will store file signatures in a
separate .sconsign file in each directory, not in a single combined
database file. This is a backwards-compatibility meaure to support
what was the default behavior prior to SCons 0.97 (i.e. before
2008). Use of this mode is discouraged and may be deprecated in a
future SCons release.

Examples:

# Explicitly stores signatures in ".sconsign.dblite"
# in the top-level SConstruct directory (the default behavior).
SConsignFile()

# Stores signatures in the file "etc/scons-signatures"
# relative to the top-level SConstruct directory.
# SCons will add a database suffix to this name.
SConsignFile("etc/scons-signatures")

# Stores signatures in the specified absolute file name.
# SCons will add a database suffix to this name.
SConsignFile("/home/me/SCons/signatures")

# Stores signatures in a separate .sconsign file
# in each directory.
SConsignFile(None)

# Stores signatures in a GNU dbm format .sconsign file
import dbm.gnu
SConsignFile(dbm_module=dbm.gnu)

env.SetDefault(key=val, [...])
Sets construction variables to default values specified with the
keyword arguments if (and only if) the variables are not already
set. The following statements are equivalent:

env.SetDefault(FOO='foo')
if 'FOO' not in env:
env['FOO'] = 'foo'

SetOption(name, value), env.SetOption(name, value)
Sets scons option variable name to value. These options are all
also settable via command-line options but the variable name may
differ from the command-line option name - see the table for
correspondences. A value set via command-line option will take
precedence over one set with SetOption, which allows setting a
project default in the scripts and temporarily overriding it via
command line. SetOption calls can also be placed in the
site_init.py file.

See the documentation in the manpage for the corresponding command
line option for information about each specific option. The value
parameter is mandatory, for option values which are boolean in
nature (that is, the command line option does not take an argument)
use a value which evaluates to true (e.g. True, 1) or false (e.g.
False, 0).

Options which affect the reading and processing of SConscript files
are not settable using SetOption since those files must be read in
order to find the SetOption call in the first place.

The settable variables with their associated command-line options
are:

┌────────────────────────┬───────────────────────────┬─────────────────────┐
│Settable name │ Command-line │ Notes │
│ │ options │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│clean │ -c, │ │
│ │ --clean, │ │
│ │ --remove │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│diskcheck │ --diskcheck │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│duplicate │ --duplicate │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│experimental │ --experimental │ since 4.2 │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│hash_chunksize │ --hash-chunksize │ Actually sets │
│ │ │ md5_chunksize. │
│ │ │ since 4.2 │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│hash_format │ --hash-format │ since 4.2 │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│help │ -h, --help │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│implicit_cache │ --implicit-cache │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│implicit_deps_changed │ --implicit-deps-changed │ Also sets │
│ │ │ implicit_cache. │
│ │ │ (settable since │
│ │ │ 4.2) │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│implicit_deps_unchanged │ --implicit-deps-unchanged │ Also sets │
│ │ │ implicit_cache. │
│ │ │ (settable since │
│ │ │ 4.2) │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│max_drift │ --max-drift │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│md5_chunksize │ --md5-chunksize │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│no_exec │ -n, │ │
│ │ --no-exec, │ │
│ │ --just-print, │ │
│ │ --dry-run, │ │
│ │ --recon │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│no_progress │ -Q │ See │
│ │ │ [4] │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│num_jobs │ -j, --jobs │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│random │ --random │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│silent │ -s, │ │
│ │ --silent, │ │
│ │ --quiet │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│stack_size │ --stack-size │ │
├────────────────────────┼───────────────────────────┼─────────────────────┤
│warn │ --warn │ │
├────────────────────────┴───────────────────────────┴─────────────────────┤
│---- │
│[a] If no_progress is set via SetOption in an SConscript │
│file (but not if set in a site_init.py file) there will │
│still be an initial status message about reading │
│SConscript files since SCons has to start reading them │
│before it can see the SetOption. │
└──────────────────────────────────────────────────────────────────────────┘
Example:

SetOption('max_drift', 0)

SideEffect(side_effect, target), env.SideEffect(side_effect, target)
Declares side_effect as a side effect of building target. Both
side_effect and target can be a list, a file name, or a node. A
side effect is a target file that is created or updated as a side
effect of building other targets. For example, a Windows PDB file
is created as a side effect of building the .obj files for a static
library, and various log files are created updated as side effects
of various TeX commands. If a target is a side effect of multiple
build commands, scons will ensure that only one set of commands is
executed at a time. Consequently, you only need to use this method
for side-effect targets that are built as a result of multiple
build commands.

Because multiple build commands may update the same side effect
file, by default the side_effect target is not automatically
removed when the target is removed by the -c option. (Note,
however, that the side_effect might be removed as part of cleaning
the directory in which it lives.) If you want to make sure the
side_effect is cleaned whenever a specific target is cleaned, you
must specify this explicitly with the Clean or env.Clean function.

This function returns the list of side effect Node objects that
were successfully added. If the list of side effects contained any
side effects that had already been added, they are not added and
included in the returned list.

Split(arg), env.Split(arg)
If arg is a string, splits on whitespace and returns a list of
strings without whitespace. This mode is the most common case, and
can be used to split a list of filenames (for example) rather than
having to type them as a list of individually quoted words. If arg
is a list or tuple returns the list or tuple unchanged. If arg is
any other type of object, returns a list containing just the
object. These non-string cases do not actually do any spliting, but
allow an argument variable to be passed to Split without having to
first check its type.

Example:

files = Split("f1.c f2.c f3.c")
files = env.Split("f4.c f5.c f6.c")
files = Split("""
f7.c
f8.c
f9.c
""")

env.subst(input, [raw, target, source, conv])
Performs construction variable interpolation (substitution) on
input, which can be a string or a sequence. Substitutable elements
take the form ${expression}, although if there is no ambiguity in
recognizing the element, the braces can be omitted. A literal $ can
be entered by using $$.

By default, leading or trailing white space will be removed from
the result, and all sequences of white space will be compressed to
a single space character. Additionally, any $( and $) character
sequences will be stripped from the returned string, The optional
raw argument may be set to 1 if you want to preserve white space
and $(-$) sequences. The raw argument may be set to 2 if you want
to additionally discard all characters between any $( and $) pairs
(as is done for signature calculation).

If input is a sequence (list or tuple), the individual elements of
the sequence will be expanded, and the results will be returned as
a list.

The optional target and source keyword arguments must be set to
lists of target and source nodes, respectively, if you want the
$TARGET, $TARGETS, $SOURCE and $SOURCES to be available for
expansion. This is usually necessary if you are calling env.subst
from within a Python function used as an SCons action.

Returned string values or sequence elements are converted to their
string representation by default. The optional conv argument may
specify a conversion function that will be used in place of the
default. For example, if you want Python objects (including SCons
Nodes) to be returned as Python objects, you can use a Python
lambda expression to pass in an unnamed function that simply
returns its unconverted argument.

Example:

print(env.subst("The C compiler is: $CC"))

def compile(target, source, env):
sourceDir = env.subst(
"${SOURCE.srcdir}",
target=target,
source=source
)

source_nodes = env.subst('$EXPAND_TO_NODELIST', conv=lambda x: x)

Tag(node, tags)
Annotates file or directory Nodes with information about how the
Package Builder should package those files or directories. All
Node-level tags are optional.

Examples:

# makes sure the built library will be installed with 644 file access mode
Tag(Library('lib.c'), UNIX_ATTR="0o644")

# marks file2.txt to be a documentation file
Tag('file2.txt', DOC)

Tool(name, [toolpath, **kwargs]), env.Tool(name, [toolpath, **kwargs])
Locates the tool specification module name and returns a callable
tool object for that tool. The tool module is searched for in
standard locations and in any paths specified by the optional
toolpath parameter. The standard locations are SCons' own internal
path for tools plus the toolpath, if any (see the Tools section in
the manual page for more details). Any additional keyword arguments
kwargs are passed to the tool module's generate function during
tool object construction.

When called, the tool object updates a construction environment
with construction variables and arranges any other initialization
needed to use the mechanisms that tool describes.

When the env.Tool form is used, the tool object is automatically
called to update env and the value of tool is appended to the
$TOOLS construction variable in that environment.

Examples:

env.Tool('gcc')
env.Tool('opengl', toolpath=['build/tools'])

When the global function Tool form is used, the tool object is
constructed but not called, as it lacks the context of an
environment to update. The tool object can be passed to an
Environment or Clone call as part of the tools keyword argument, in
which case the tool is applied to the environment being
constructed, or it can be called directly, in which case a
construction environment to update must be passed as the argument.
Either approach will also update the $TOOLS construction variable.

Examples:

env = Environment(tools=[Tool('msvc')])

env = Environment()
msvctool = Tool('msvc')
msvctool(env) # adds 'msvc' to the TOOLS variable
gltool = Tool('opengl', toolpath = ['tools'])
gltool(env) # adds 'opengl' to the TOOLS variable

Changed in SCons 4.2: env.Tool now returns the tool object,
previously it did not return (i.e. returned None).

Value(value, [built_value], [name]), env.Value(value, [built_value],
[name])
Returns a Node object representing the specified Python value.
Value Nodes can be used as dependencies of targets. If the result
of calling str(value) changes between SCons runs, any targets
depending on Value(value) will be rebuilt. (This is true even when
using timestamps to decide if files are up-to-date.) When using
timestamp source signatures, Value Nodes' timestamps are equal to
the system time when the Node is created. name can be provided as
an alternative name for the resulting Value node; this is advised
if the value parameter can't be converted to a string.

The returned Value Node object has a write() method that can be
used to "build" a Value Node by setting a new value. The optional
built_value argument can be specified when the Value Node is
created to indicate the Node should already be considered "built."
There is a corresponding read() method that will return the built
value of the Node.

Examples:

env = Environment()

def create(target, source, env):
# A function that will write a 'prefix=$SOURCE'
# string into the file name specified as the
# $TARGET.
with open(str(target[0]), 'wb') as f:
f.write('prefix=' + source[0].get_contents())

# Fetch the prefix= argument, if any, from the command
# line, and use /usr/local as the default.
prefix = ARGUMENTS.get('prefix', '/usr/local')

# Attach a .Config() builder for the above function action
# to the construction environment.
env['BUILDERS']['Config'] = Builder(action = create)
env.Config(target = 'package-config', source = Value(prefix))

def build_value(target, source, env):
# A function that "builds" a Python Value by updating
# the Python value with the contents of the file
# specified as the source of the Builder call ($SOURCE).
target[0].write(source[0].get_contents())

output = env.Value('before')
input = env.Value('after')

# Attach a .UpdateValue() builder for the above function
# action to the construction environment.
env['BUILDERS']['UpdateValue'] = Builder(action = build_value)
env.UpdateValue(target = Value(output), source = Value(input))

VariantDir(variant_dir, src_dir, [duplicate]),
env.VariantDir(variant_dir, src_dir, [duplicate])
Sets up a mapping to define a variant build directory in
variant_dir. src_dir may not be underneath variant_dir. A
VariantDir mapping is global, even if called using the
env.VariantDir form. VariantDir can be called multiple times with
the same src_dir to set up multiple variant builds with different
options.

Note if variant_dir is not under the project top directory, target
selection rules will not pick targets in the variant directory
unless they are explicitly specified.

When files in variant_dir are referenced, SCons backfills as needed
with files from src_dir to create a complete build directory. By
default, SCons physically duplicates the source files, SConscript
files, and directory structure as needed into the variant
directory. Thus, a build performed in the variant directory is
guaranteed to be identical to a build performed in the source
directory even if intermediate source files are generated during
the build, or if preprocessors or other scanners search for
included files using paths relative to the source file, or if
individual compilers or other invoked tools are hard-coded to put
derived files in the same directory as source files. Only the files
SCons calculates are needed for the build are duplicated into
variant_dir. If possible on the platform, the duplication is
performed by linking rather than copying. This behavior is affected
by the --duplicate command-line option.

Duplicating the source files may be disabled by setting the
duplicate argument to False. This will cause SCons to invoke
Builders using the path names of source files in src_dir and the
path names of derived files within variant_dir. This is more
efficient than duplicating, and is safe for most builds; revert to
duplicate=True if it causes problems.

VariantDir works most naturally when used with a subsidiary
SConscript file. The subsidiary SConscript file must be called as
if it were in variant_dir, regardless of the value of duplicate.
When calling an SConscript file, you can use the exports keyword
argument to pass parameters (individually or as an appropriately
set up environment) so the SConscript can pick up the right
settings for that variant build. The SConscript must Import these
to use them. Example:

env1 = Environment(...settings for variant1...)
env2 = Environment(...settings for variant2...)

# run src/SConscript in two variant directories
VariantDir('build/variant1', 'src')
SConscript('build/variant1/SConscript', exports={"env": env1})
VariantDir('build/variant2', 'src')
SConscript('build/variant2/SConscript', exports={"env": env2})

See also the SConscript function for another way to specify a
variant directory in conjunction with calling a subsidiary
SConscript file.

More examples:

# use names in the build directory, not the source directory
VariantDir('build', 'src', duplicate=0)
Program('build/prog', 'build/source.c')

# this builds both the source and docs in a separate subtree
VariantDir('build', '.', duplicate=0)
SConscript(dirs=['build/src','build/doc'])

# same as previous example, but only uses SConscript
SConscript(dirs='src', variant_dir='build/src', duplicate=0)
SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)

WhereIs(program, [path, pathext, reject]), env.WhereIs(program, [path,
pathext, reject])
Searches for the specified executable program, returning the full
path to the program or None.

When called as a construction environment method, searches the
paths in the path keyword argument, or if None (the default) the
paths listed in the construction environment (env['ENV']['PATH']).
The external environment's path list (os.environ['PATH']) is used
as a fallback if the key env['ENV']['PATH'] does not exist.

On Windows systems, searches for executable programs with any of
the file extensions listed in the pathext keyword argument, or if
None (the default) the pathname extensions listed in the
construction environment (env['ENV']['PATHEXT']). The external
environment's pathname extensions list (os.environ['PATHEXT']) is
used as a fallback if the key env['ENV']['PATHEXT'] does not exist.

When called as a global function, uses the external environment's
path os.environ['PATH'] and path extensions os.environ['PATHEXT'],
respectively, if path and pathext are None.

Will not select any path name or names in the optional reject list.

SConscript Variables
In addition to the global functions and methods, scons supports a
number of variables that can be used in SConscript files to affect how
you want the build to be performed.

ARGLIST
A list of the keyword=value arguments specified on the command
line. Each element in the list is a tuple containing the argument.
The separate keyword and value elements of the tuple can be
accessed by subscripting for elements [0] and [1] of the tuple, or,
more readably, by using tuple unpacking. Example:

print("first keyword, value =", ARGLIST[0][0], ARGLIST[0][1])
print("second keyword, value =", ARGLIST[1][0], ARGLIST[1][1])
key, value = ARGLIST[2]
print("third keyword, value =", key, value)
for key, value in ARGLIST:
# process key and value

ARGUMENTS
A dictionary of all the keyword=value arguments specified on the
command line. The dictionary is not in order, and if a given
keyword has more than one value assigned to it on the command line,
the last (right-most) value is the one in the ARGUMENTS dictionary.

Example:

if ARGUMENTS.get('debug', 0):
env = Environment(CCFLAGS='-g')
else:
env = Environment()

BUILD_TARGETS
A list of the targets which scons has been asked to build. The
contents will be either those targets listed on the command line,
or, if none, those targets set via calls to the Default function.
It does not contain any dependent targets that scons selects for
building as a result of making the sure the specified targets are
up to date, if those targets did not appear on the command line.
The list is empty if neither command line targets or Default calls
are present.

The elements of this list may be strings or nodes, so you should
run the list through the Python str function to make sure any Node
path names are converted to strings.

Because this list may be taken from the list of targets specified
using the Default function, the contents of the list may change on
each successive call to Default. See the DEFAULT_TARGETS list,
below, for additional information.

Example:

if 'foo' in BUILD_TARGETS:
print("Don't forget to test the `foo' program!")
if 'special/program' in BUILD_TARGETS:
SConscript('special')

COMMAND_LINE_TARGETS
A list of the targets explicitly specified on the command line. If
there are command line targets, this list will have the same
contents as BUILD_TARGETS. If there are no targets specified on the
command line, the list is empty. The elements of this list are
strings. This can be used, for example, to take specific actions
only when certain targets are explicitly being built.

Example:

if 'foo' in COMMAND_LINE_TARGETS:
print("Don't forget to test the `foo' program!")
if 'special/program' in COMMAND_LINE_TARGETS:
SConscript('special')

DEFAULT_TARGETS
A list of the target nodes that have been specified using the
Default function. If there are no command line targets, this list
will have the same contents as BUILD_TARGETS. Since the elements of
the list are nodes, you need to call the Python str function on
them to get the path name for each Node.

Example:

print(str(DEFAULT_TARGETS[0]))
if 'foo' in [str(t) for t in DEFAULT_TARGETS]:
print("Don't forget to test the `foo' program!")

The contents of the DEFAULT_TARGETS list change on on each
successive call to the Default function:

print([str(t) for t in DEFAULT_TARGETS]) # originally []
Default('foo')
print([str(t) for t in DEFAULT_TARGETS]) # now a node ['foo']
Default('bar')
print([str(t) for t in DEFAULT_TARGETS]) # now a node ['foo', 'bar']
Default(None)
print([str(t) for t in DEFAULT_TARGETS]) # back to []

Consequently, be sure to use DEFAULT_TARGETS only after you've made
all of your Default() calls, or else simply be careful of the order
of these statements in your SConscript files so that you don't look
for a specific default target before it's actually been added to
the list.

These variables may be accessed from custom Python modules that you
import into an SConscript file by adding the following to the Python
module:

from SCons.Script import *

Construction Variables
A construction environment has an associated dictionary of construction
variables that are used by built-in or user-supplied build rules.
Construction variable naming must follow the same rules as Python
identifier naming: the initial character must be an underscore or
letter, followed by any number of underscores, letters, or digits. A
construction environment is not a Python dictionary itself, but it can
be indexed like one to access a construction variable:

env["CC"] = "cc"
flags = env.get("CPPDEFINES", [])

Construction variables can also be retrieved and set by using the
Dictionary method of the construction environment to create an actual
dictionary:

cvars = env.Dictionary()
cvars["CC"] = "cc"

Construction variables can also be passed to the construction
environment constructor:

env = Environment(CC="cc")

or when copying a construction environment using the Clone method:

env2 = env.Clone(CC="cl.exe")

Construction variables can also be supplied as keyword arguments to a
builder, in which case those settings affect only the work done by that
builder call, and not the construction environment as a whole. This
concept is called an override:

env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

A number of useful construction variables are automatically defined by
scons for each supported platform, and you can modify these or define
any additional construction variables for your own use, taking care not
to overwrite ones which SCons is using. The following is a list of the
possible automatically defined construction variables.

Note the actual list available at execution time will never include all
of these, as the ones detected as not being useful (wrong platform,
necessary external command or files not installed, etc.) will not be
set up. Correct build setups should be resilient to the possible
absence of certain construction variables before using them, for
example by using a Python dictionary get method to retrieve the value
and taking alternative action if the return indicates the variable is
unset. The env.Dump method can be called to examine the construction
variables set in a particular environment.

__LDMODULEVERSIONFLAGS
This construction variable automatically introduces
$_LDMODULEVERSIONFLAGS if $LDMODULEVERSION is set. Othervise it
evaluates to an empty string.

__SHLIBVERSIONFLAGS
This construction variable automatically introduces
$_SHLIBVERSIONFLAGS if $SHLIBVERSION is set. Othervise it evaluates
to an empty string.

APPLELINK_COMPATIBILITY_VERSION
On Mac OS X this is used to set the linker flag:
-compatibility_version

The value is specified as X[.Y[.Z]] where X is between 1 and 65535,
Y can be omitted or between 1 and 255, Z can be omitted or between
1 and 255. This value will be derived from $SHLIBVERSION if not
specified. The lowest digit will be dropped and replaced by a 0.

If the $APPLELINK_NO_COMPATIBILITY_VERSION is set then no
-compatibility_version will be output.

See MacOS's ld manpage for more details

_APPLELINK_COMPATIBILITY_VERSION
A macro (by default a generator function) used to create the linker
flags to specify apple's linker's -compatibility_version flag. The
default generator uses $APPLELINK_COMPATIBILITY_VERSION and
$APPLELINK_NO_COMPATIBILITY_VERSION and $SHLIBVERSION to determine
the correct flag.

APPLELINK_CURRENT_VERSION
On Mac OS X this is used to set the linker flag: -current_version

The value is specified as X[.Y[.Z]] where X is between 1 and 65535,
Y can be omitted or between 1 and 255, Z can be omitted or between
1 and 255. This value will be set to $SHLIBVERSION if not
specified.

If the $APPLELINK_NO_CURRENT_VERSION is set then no
-current_version will be output.

See MacOS's ld manpage for more details

_APPLELINK_CURRENT_VERSION
A macro (by default a generator function) used to create the linker
flags to specify apple's linker's -current_version flag. The
default generator uses $APPLELINK_CURRENT_VERSION and
$APPLELINK_NO_CURRENT_VERSION and $SHLIBVERSION to determine the
correct flag.

APPLELINK_NO_COMPATIBILITY_VERSION
Set this to any True (1|True|non-empty string) value to disable
adding -compatibility_version flag when generating versioned shared
libraries.

This overrides $APPLELINK_COMPATIBILITY_VERSION.

APPLELINK_NO_CURRENT_VERSION
Set this to any True (1|True|non-empty string) value to disable
adding -current_version flag when generating versioned shared
libraries.

This overrides $APPLELINK_CURRENT_VERSION.

AR
The static library archiver.

ARCHITECTURE
Specifies the system architecture for which the package is being
built. The default is the system architecture of the machine on
which SCons is running. This is used to fill in the Architecture:
field in an Ipkg control file, and the BuildArch: field in the RPM
.spec file, as well as forming part of the name of a generated RPM
package file.

See the Package builder.

ARCOM
The command line used to generate a static library from object
files.

ARCOMSTR
The string displayed when a static library is generated from object
files. If this is not set, then $ARCOM (the command line) is
displayed.

env = Environment(ARCOMSTR = "Archiving $TARGET")

ARFLAGS
General options passed to the static library archiver.

AS
The assembler.

ASCOM
The command line used to generate an object file from an
assembly-language source file.

ASCOMSTR
The string displayed when an object file is generated from an
assembly-language source file. If this is not set, then $ASCOM (the
command line) is displayed.

env = Environment(ASCOMSTR = "Assembling $TARGET")

ASFLAGS
General options passed to the assembler.

ASPPCOM
The command line used to assemble an assembly-language source file
into an object file after first running the file through the C
preprocessor. Any options specified in the $ASFLAGS and $CPPFLAGS
construction variables are included on this command line.

ASPPCOMSTR
The string displayed when an object file is generated from an
assembly-language source file after first running the file through
the C preprocessor. If this is not set, then $ASPPCOM (the command
line) is displayed.

env = Environment(ASPPCOMSTR = "Assembling $TARGET")

ASPPFLAGS
General options when an assembling an assembly-language source file
into an object file after first running the file through the C
preprocessor. The default is to use the value of $ASFLAGS.

BIBTEX
The bibliography generator for the TeX formatter and typesetter and
the LaTeX structured formatter and typesetter.

BIBTEXCOM
The command line used to call the bibliography generator for the
TeX formatter and typesetter and the LaTeX structured formatter and
typesetter.

BIBTEXCOMSTR
The string displayed when generating a bibliography for TeX or
LaTeX. If this is not set, then $BIBTEXCOM (the command line) is
displayed.

env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")

BIBTEXFLAGS
General options passed to the bibliography generator for the TeX
formatter and typesetter and the LaTeX structured formatter and
typesetter.

BUILDERS
A dictionary mapping the names of the builders available through
the construction environment to underlying Builder objects. Custom
builders need to be added to this to make them available.

A platform-dependent default list of builders such as Program,
Library etc. is used to populate this construction variable when
the construction environment is initialized via the
presence/absence of the tools those builders depend on. $BUILDERS
can be examined to learn which builders will actually be available
at run-time.

Note that if you initialize this construction variable through
assignment when the construction environment is created, that value
for $BUILDERS will override any defaults:

bld = Builder(action='foobuild < $SOURCE > $TARGET')
env = Environment(BUILDERS={'NewBuilder': bld})

To instead use a new Builder object in addition to the default
Builders, add your new Builder object like this:

env = Environment()
env.Append(BUILDERS={'NewBuilder': bld})

or this:

env = Environment()
env['BUILDERS']['NewBuilder'] = bld

CACHEDIR_CLASS
The class type that SCons should use when instantiating a new
CacheDir for the given environment. It must be a subclass of the
SCons.CacheDir.CacheDir class.

CC
The C compiler.

CCCOM
The command line used to compile a C source file to a (static)
object file. Any options specified in the $CFLAGS, $CCFLAGS and
$CPPFLAGS construction variables are included on this command line.
See also $SHCCCOM for compiling to shared objects.

CCCOMSTR
If set, the string displayed when a C source file is compiled to a
(static) object file. If not set, then $CCCOM (the command line) is
displayed. See also $SHCCCOMSTR for compiling to shared objects.

env = Environment(CCCOMSTR = "Compiling static object $TARGET")

CCDEPFLAGS
Options to pass to C or C++ compiler to generate list of dependency
files.

This is set only by compilers which support this functionality.
(gcc, clang, and msvc currently)

CCFLAGS
General options that are passed to the C and C++ compilers. See
also $SHCCFLAGS for compiling to shared objects.

CCPCHFLAGS
Options added to the compiler command line to support building with
precompiled headers. The default value expands expands to the
appropriate Microsoft Visual C++ command-line options when the $PCH
construction variable is set.

CCPDBFLAGS
Options added to the compiler command line to support storing
debugging information in a Microsoft Visual C++ PDB file. The
default value expands expands to appropriate Microsoft Visual C++
command-line options when the $PDB construction variable is set.

The Visual C++ compiler option that SCons uses by default to
generate PDB information is /Z7. This works correctly with parallel
(-j) builds because it embeds the debug information in the
intermediate object files, as opposed to sharing a single PDB file
between multiple object files. This is also the only way to get
debug information embedded into a static library. Using the /Zi
instead may yield improved link-time performance, although parallel
builds will no longer work.

You can generate PDB files with the /Zi switch by overriding the
default $CCPDBFLAGS variable as follows:

env['CCPDBFLAGS'] = ['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}']

An alternative would be to use the /Zi to put the debugging
information in a separate .pdb file for each object file by
overriding the $CCPDBFLAGS variable as follows:

env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'

CCVERSION
The version number of the C compiler. This may or may not be set,
depending on the specific C compiler being used.

CFILESUFFIX
The suffix for C source files. This is used by the internal CFile
builder when generating C files from Lex (.l) or YACC (.y) input
files. The default suffix, of course, is .c (lower case). On
case-insensitive systems (like Windows), SCons also treats .C
(upper case) files as C files.

CFLAGS
General options that are passed to the C compiler (C only; not
C++). See also $SHCFLAGS for compiling to shared objects.

CHANGE_SPECFILE
A hook for modifying the file that controls the packaging build
(the .spec for RPM, the control for Ipkg, the .wxs for MSI). If
set, the function will be called after the SCons template for the
file has been written.

See the Package builder.

CHANGED_SOURCES
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

CHANGED_TARGETS
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

CHANGELOG
The name of a file containing the change log text to be included in
the package. This is included as the %changelog section of the RPM
.spec file.

See the Package builder.

COMPILATIONDB_COMSTR
The string displayed when the CompilationDatabase builder's action
is run.

COMPILATIONDB_PATH_FILTER
A string which instructs CompilationDatabase to only include
entries where the output member matches the pattern in the filter
string using fnmatch, which uses glob style wildcards.

The default value is an empty string '', which disables filtering.

COMPILATIONDB_USE_ABSPATH
A boolean flag to instruct CompilationDatabase whether to write the
file and output members in the compilation database using absolute
or relative paths.

The default value is False (use relative paths)

_concat
A function used to produce variables like $_CPPINCFLAGS. It takes
four mandatory arguments, and up to 4 additional optional
arguments: 1) a prefix to concatenate onto each element, 2) a list
of elements, 3) a suffix to concatenate onto each element, 4) an
environment for variable interpolation, 5) an optional function
that will be called to transform the list before concatenation, 6)
an optionally specified target (Can use TARGET), 7) an optionally
specified source (Can use SOURCE), 8) optional affect_signature
flag which will wrap non-empty returned value with $( and $) to
indicate the contents should not affect the signature of the
generated command line.

env['_CPPINCFLAGS'] = '${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE, affect_signature=False)}'

CONFIGUREDIR
The name of the directory in which Configure context test files are
written. The default is .sconf_temp in the top-level directory
containing the SConstruct file.

CONFIGURELOG
The name of the Configure context log file. The default is
config.log in the top-level directory containing the SConstruct
file.

_CPPDEFFLAGS
An automatically-generated construction variable containing the C
preprocessor command-line options to define values. The value of
$_CPPDEFFLAGS is created by respectively prepending and appending
$CPPDEFPREFIX and $CPPDEFSUFFIX to each definition in $CPPDEFINES.

CPPDEFINES
A platform independent specification of C preprocessor macro
definitions. The definitions will be added to command lines through
the automatically-generated $_CPPDEFFLAGS construction variable
(see above), which is constructed according to the type of value of
$CPPDEFINES:

If $CPPDEFINES is a string, the values of the $CPPDEFPREFIX and
$CPPDEFSUFFIX construction variables will be respectively prepended
and appended to each definition in $CPPDEFINES.

# Will add -Dxyz to POSIX compiler command lines,
# and /Dxyz to Microsoft Visual C++ command lines.
env = Environment(CPPDEFINES='xyz')

If $CPPDEFINES is a list, the values of the $CPPDEFPREFIX and
$CPPDEFSUFFIX construction variables will be respectively prepended
and appended to each element in the list. If any element is a list
or tuple, then the first item is the name being defined and the
second item is its value:

# Will add -DB=2 -DA to POSIX compiler command lines,
# and /DB=2 /DA to Microsoft Visual C++ command lines.
env = Environment(CPPDEFINES=[('B', 2), 'A'])

If $CPPDEFINES is a dictionary, the values of the $CPPDEFPREFIX and
$CPPDEFSUFFIX construction variables will be respectively prepended
and appended to each item from the dictionary. The key of each
dictionary item is a name being defined to the dictionary item's
corresponding value; if the value is None, then the name is defined
without an explicit value. Note that the resulting flags are sorted
by keyword to ensure that the order of the options on the command
line is consistent each time scons is run.

# Will add -DA -DB=2 to POSIX compiler command lines,
# and /DA /DB=2 to Microsoft Visual C++ command lines.
env = Environment(CPPDEFINES={'B':2, 'A':None})

CPPDEFPREFIX
The prefix used to specify preprocessor macro definitions on the C
compiler command line. This will be prepended to each definition in
the $CPPDEFINES construction variable when the $_CPPDEFFLAGS
variable is automatically generated.

CPPDEFSUFFIX
The suffix used to specify preprocessor macro definitions on the C
compiler command line. This will be appended to each definition in
the $CPPDEFINES construction variable when the $_CPPDEFFLAGS
variable is automatically generated.

CPPFLAGS
User-specified C preprocessor options. These will be included in
any command that uses the C preprocessor, including not just
compilation of C and C++ source files via the $CCCOM, $SHCCCOM,
$CXXCOM and $SHCXXCOM command lines, but also the $FORTRANPPCOM,
$SHFORTRANPPCOM, $F77PPCOM and $SHF77PPCOM command lines used to
compile a Fortran source file, and the $ASPPCOM command line used
to assemble an assembly language source file, after first running
each file through the C preprocessor. Note that this variable does
not contain -I (or similar) include search path options that scons
generates automatically from $CPPPATH. See $_CPPINCFLAGS, below,
for the variable that expands to those options.

_CPPINCFLAGS
An automatically-generated construction variable containing the C
preprocessor command-line options for specifying directories to be
searched for include files. The value of $_CPPINCFLAGS is created
by respectively prepending and appending $INCPREFIX and $INCSUFFIX
to each directory in $CPPPATH.

CPPPATH
The list of directories that the C preprocessor will search for
include directories. The C/C++ implicit dependency scanner will
search these directories for include files. In general it's not
advised to put include directory directives directly into $CCFLAGS
or $CXXFLAGS as the result will be non-portable and the directories
will not be searched by the dependency scanner. $CPPPATH should be
a list of path strings, or a single string, not a pathname list
joined by Python's os.sep.

Note: directory names in $CPPPATH will be looked-up relative to the
directory of the SConscript file when they are used in a command.
To force scons to look-up a directory relative to the root of the
source tree use the # prefix:

env = Environment(CPPPATH='#/include')

The directory look-up can also be forced using the Dir function:

include = Dir('include')
env = Environment(CPPPATH=include)

The directory list will be added to command lines through the
automatically-generated $_CPPINCFLAGS construction variable, which
is constructed by respectively prepending and appending the values
of the $INCPREFIX and $INCSUFFIX construction variables to each
directory in $CPPPATH. Any command lines you define that need the
$CPPPATH directory list should include $_CPPINCFLAGS:

env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")

CPPSUFFIXES
The list of suffixes of files that will be scanned for C
preprocessor implicit dependencies (#include lines). The default
list is:

[".c", ".C", ".cxx", ".cpp", ".c++", ".cc",
".h", ".H", ".hxx", ".hpp", ".hh",
".F", ".fpp", ".FPP",
".m", ".mm",
".S", ".spp", ".SPP"]

CXX
The C++ compiler. See also $SHCXX for compiling to shared objects..

CXXCOM
The command line used to compile a C++ source file to an object
file. Any options specified in the $CXXFLAGS and $CPPFLAGS
construction variables are included on this command line. See also
$SHCXXCOM for compiling to shared objects..

CXXCOMSTR
If set, the string displayed when a C++ source file is compiled to
a (static) object file. If not set, then $CXXCOM (the command line)
is displayed. See also $SHCXXCOMSTR for compiling to shared
objects..

env = Environment(CXXCOMSTR = "Compiling static object $TARGET")

CXXFILESUFFIX
The suffix for C++ source files. This is used by the internal
CXXFile builder when generating C++ files from Lex (.ll) or YACC
(.yy) input files. The default suffix is .cc. SCons also treats
files with the suffixes .cpp, .cxx, .c++, and .C++ as C++ files,
and files with .mm suffixes as Objective C++ files. On
case-sensitive systems (Linux, UNIX, and other POSIX-alikes), SCons
also treats .C (upper case) files as C++ files.

CXXFLAGS
General options that are passed to the C++ compiler. By default,
this includes the value of $CCFLAGS, so that setting $CCFLAGS
affects both C and C++ compilation. If you want to add C++-specific
flags, you must set or override the value of $CXXFLAGS. See also
$SHCXXFLAGS for compiling to shared objects..

CXXVERSION
The version number of the C++ compiler. This may or may not be set,
depending on the specific C++ compiler being used.

DC
The D compiler to use. See also $SHDC for compiling to shared
objects.

DCOM
The command line used to compile a D file to an object file. Any
options specified in the $DFLAGS construction variable is included
on this command line. See also $SHDCOM for compiling to shared
objects.

DCOMSTR
If set, the string displayed when a D source file is compiled to a
(static) object file. If not set, then $DCOM (the command line) is
displayed. See also $SHDCOMSTR for compiling to shared objects.

DDEBUG
List of debug tags to enable when compiling.

DDEBUGPREFIX
DDEBUGPREFIX.

DDEBUGSUFFIX
DDEBUGSUFFIX.

DESCRIPTION
A long description of the project being packaged. This is included
in the relevant section of the file that controls the packaging
build.

See the Package builder.

DESCRIPTION_lang
A language-specific long description for the specified lang. This
is used to populate a %description -l section of an RPM .spec file.

See the Package builder.

DFILESUFFIX
DFILESUFFIX.

DFLAGPREFIX
DFLAGPREFIX.

DFLAGS
General options that are passed to the D compiler.

DFLAGSUFFIX
DFLAGSUFFIX.

DINCPREFIX
DINCPREFIX.

DINCSUFFIX
DLIBFLAGSUFFIX.

Dir
A function that converts a string into a Dir instance relative to
the target being built.

Dirs
A function that converts a list of strings into a list of Dir
instances relative to the target being built.

DLIB
Name of the lib tool to use for D codes.

DLIBCOM
The command line to use when creating libraries.

DLIBDIRPREFIX
DLIBLINKPREFIX.

DLIBDIRSUFFIX
DLIBLINKSUFFIX.

DLIBFLAGPREFIX
DLIBFLAGPREFIX.

DLIBFLAGSUFFIX
DLIBFLAGSUFFIX.

DLIBLINKPREFIX
DLIBLINKPREFIX.

DLIBLINKSUFFIX
DLIBLINKSUFFIX.

DLINK
Name of the linker to use for linking systems including D sources.
See also $SHDLINK for linking shared objects.

DLINKCOM
The command line to use when linking systems including D sources.
See also $SHDLINKCOM for linking shared objects.

DLINKFLAGPREFIX
DLINKFLAGPREFIX.

DLINKFLAGS
List of linker flags. See also $SHDLINKFLAGS for linking shared
objects.

DLINKFLAGSUFFIX
DLINKFLAGSUFFIX.

DOCBOOK_DEFAULT_XSL_EPUB
The default XSLT file for the DocbookEpub builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTML
The default XSLT file for the DocbookHtml builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
The default XSLT file for the DocbookHtmlChunked builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTMLHELP
The default XSLT file for the DocbookHtmlhelp builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_MAN
The default XSLT file for the DocbookMan builder within the current
environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_PDF
The default XSLT file for the DocbookPdf builder within the current
environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_SLIDESHTML
The default XSLT file for the DocbookSlidesHtml builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_SLIDESPDF
The default XSLT file for the DocbookSlidesPdf builder within the
current environment, if no other XSLT gets specified via keyword.

DOCBOOK_FOP
The path to the PDF renderer fop or xep, if one of them is
installed (fop gets checked first).

DOCBOOK_FOPCOM
The full command-line for the PDF renderer fop or xep.

DOCBOOK_FOPCOMSTR
The string displayed when a renderer like fop or xep is used to
create PDF output from an XML file.

DOCBOOK_FOPFLAGS
Additonal command-line flags for the PDF renderer fop or xep.

DOCBOOK_XMLLINT
The path to the external executable xmllint, if it's installed.
Note, that this is only used as last fallback for resolving
XIncludes, if no lxml Python binding can be imported in the current
system.

DOCBOOK_XMLLINTCOM
The full command-line for the external executable xmllint.

DOCBOOK_XMLLINTCOMSTR
The string displayed when xmllint is used to resolve XIncludes for
a given XML file.

DOCBOOK_XMLLINTFLAGS
Additonal command-line flags for the external executable xmllint.

DOCBOOK_XSLTPROC
The path to the external executable xsltproc (or saxon, xalan), if
one of them is installed. Note, that this is only used as last
fallback for XSL transformations, if no lxml Python binding can be
imported in the current system.

DOCBOOK_XSLTPROCCOM
The full command-line for the external executable xsltproc (or
saxon, xalan).

DOCBOOK_XSLTPROCCOMSTR
The string displayed when xsltproc is used to transform an XML file
via a given XSLT stylesheet.

DOCBOOK_XSLTPROCFLAGS
Additonal command-line flags for the external executable xsltproc
(or saxon, xalan).

DOCBOOK_XSLTPROCPARAMS
Additonal parameters that are not intended for the XSLT processor
executable, but the XSL processing itself. By default, they get
appended at the end of the command line for saxon and saxon-xslt,
respectively.

DPATH
List of paths to search for import modules.

DRPATHPREFIX
DRPATHPREFIX.

DRPATHSUFFIX
DRPATHSUFFIX.

DSUFFIXES
The list of suffixes of files that will be scanned for imported D
package files. The default list is ['.d'].

DVERPREFIX
DVERPREFIX.

DVERSIONS
List of version tags to enable when compiling.

DVERSUFFIX
DVERSUFFIX.

DVIPDF
The TeX DVI file to PDF file converter.

DVIPDFCOM
The command line used to convert TeX DVI files into a PDF file.

DVIPDFCOMSTR
The string displayed when a TeX DVI file is converted into a PDF
file. If this is not set, then $DVIPDFCOM (the command line) is
displayed.

DVIPDFFLAGS
General options passed to the TeX DVI file to PDF file converter.

DVIPS
The TeX DVI file to PostScript converter.

DVIPSFLAGS
General options passed to the TeX DVI file to PostScript converter.

ENV
The execution environment - a dictionary of environment variables
used when SCons invokes external commands to build targets defined
in this construction environment. When $ENV is passed to a command,
all list values are assumed to be path lists and are joined using
the search path separator. Any other non-string values are coerced
to a string.

Note that by default SCons does not propagate the environment in
effect when you execute scons (the "shell environment") to the
execution environment. This is so that builds will be guaranteed
repeatable regardless of the environment variables set at the time
scons is invoked. If you want to propagate a shell environment
variable to the commands executed to build target files, you must
do so explicitly. A common example is the system PATH environment
variable, so that scons will find utilities the same way as the
invoking shell (or other process):

import os
env = Environment(ENV={'PATH': os.environ['PATH']})

Although it is usually not recommended, you can propagate the
entire shell environment in one go:

import os
env = Environment(ENV=os.environ.copy())

ESCAPE
A function that will be called to escape shell special characters
in command lines. The function should take one argument: the
command line string to escape; and should return the escaped
command line.

F03
The Fortran 03 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F03 if you need to use a
specific compiler or compiler version for Fortran 03 files.

F03COM
The command line used to compile a Fortran 03 source file to an
object file. You only need to set $F03COM if you need to use a
specific command line for Fortran 03 files. You should normally set
the $FORTRANCOM variable, which specifies the default command line
for all Fortran versions.

F03COMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to an object file. If not set, then $F03COM or $FORTRANCOM
(the command line) is displayed.

F03FILESUFFIXES
The list of file extensions for which the F03 dialect will be used.
By default, this is ['.f03']

F03FLAGS
General user-specified options that are passed to the Fortran 03
compiler. Note that this variable does not contain -I (or similar)
include search path options that scons generates automatically from
$F03PATH. See $_F03INCFLAGS below, for the variable that expands to
those options. You only need to set $F03FLAGS if you need to define
specific user options for Fortran 03 files. You should normally set
the $FORTRANFLAGS variable, which specifies the user-specified
options passed to the default Fortran compiler for all Fortran
versions.

_F03INCFLAGS
An automatically-generated construction variable containing the
Fortran 03 compiler command-line options for specifying directories
to be searched for include files. The value of $_F03INCFLAGS is
created by appending $INCPREFIX and $INCSUFFIX to the beginning and
end of each directory in $F03PATH.

F03PATH
The list of directories that the Fortran 03 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F03FLAGS because the result will be
non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F03PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to look-up a directory relative to the
root of the source tree use #: You only need to set $F03PATH if you
need to define a specific include path for Fortran 03 files. You
should normally set the $FORTRANPATH variable, which specifies the
include path for the default Fortran compiler for all Fortran
versions.

env = Environment(F03PATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F03PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F03INCFLAGS construction variable, which
is constructed by appending the values of the $INCPREFIX and
$INCSUFFIX construction variables to the beginning and end of each
directory in $F03PATH. Any command lines you define that need the
F03PATH directory list should include $_F03INCFLAGS:

env = Environment(F03COM="my_compiler $_F03INCFLAGS -c -o $TARGET $SOURCE")

F03PPCOM
The command line used to compile a Fortran 03 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F03FLAGS and $CPPFLAGS
construction variables are included on this command line. You only
need to set $F03PPCOM if you need to use a specific C-preprocessor
command line for Fortran 03 files. You should normally set the
$FORTRANPPCOM variable, which specifies the default C-preprocessor
command line for all Fortran versions.

F03PPCOMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to an object file after first running the file through the
C preprocessor. If not set, then $F03PPCOM or $FORTRANPPCOM (the
command line) is displayed.

F03PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F03 dialect will be used. By default, this is
empty.

F08
The Fortran 08 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F08 if you need to use a
specific compiler or compiler version for Fortran 08 files.

F08COM
The command line used to compile a Fortran 08 source file to an
object file. You only need to set $F08COM if you need to use a
specific command line for Fortran 08 files. You should normally set
the $FORTRANCOM variable, which specifies the default command line
for all Fortran versions.

F08COMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to an object file. If not set, then $F08COM or $FORTRANCOM
(the command line) is displayed.

F08FILESUFFIXES
The list of file extensions for which the F08 dialect will be used.
By default, this is ['.f08']

F08FLAGS
General user-specified options that are passed to the Fortran 08
compiler. Note that this variable does not contain -I (or similar)
include search path options that scons generates automatically from
$F08PATH. See $_F08INCFLAGS below, for the variable that expands to
those options. You only need to set $F08FLAGS if you need to define
specific user options for Fortran 08 files. You should normally set
the $FORTRANFLAGS variable, which specifies the user-specified
options passed to the default Fortran compiler for all Fortran
versions.

_F08INCFLAGS
An automatically-generated construction variable containing the
Fortran 08 compiler command-line options for specifying directories
to be searched for include files. The value of $_F08INCFLAGS is
created by appending $INCPREFIX and $INCSUFFIX to the beginning and
end of each directory in $F08PATH.

F08PATH
The list of directories that the Fortran 08 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F08FLAGS because the result will be
non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F08PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to look-up a directory relative to the
root of the source tree use #: You only need to set $F08PATH if you
need to define a specific include path for Fortran 08 files. You
should normally set the $FORTRANPATH variable, which specifies the
include path for the default Fortran compiler for all Fortran
versions.

env = Environment(F08PATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F08PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F08INCFLAGS construction variable, which
is constructed by appending the values of the $INCPREFIX and
$INCSUFFIX construction variables to the beginning and end of each
directory in $F08PATH. Any command lines you define that need the
F08PATH directory list should include $_F08INCFLAGS:

env = Environment(F08COM="my_compiler $_F08INCFLAGS -c -o $TARGET $SOURCE")

F08PPCOM
The command line used to compile a Fortran 08 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F08FLAGS and $CPPFLAGS
construction variables are included on this command line. You only
need to set $F08PPCOM if you need to use a specific C-preprocessor
command line for Fortran 08 files. You should normally set the
$FORTRANPPCOM variable, which specifies the default C-preprocessor
command line for all Fortran versions.

F08PPCOMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to an object file after first running the file through the
C preprocessor. If not set, then $F08PPCOM or $FORTRANPPCOM (the
command line) is displayed.

F08PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F08 dialect will be used. By default, this is
empty.

F77
The Fortran 77 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F77 if you need to use a
specific compiler or compiler version for Fortran 77 files.

F77COM
The command line used to compile a Fortran 77 source file to an
object file. You only need to set $F77COM if you need to use a
specific command line for Fortran 77 files. You should normally set
the $FORTRANCOM variable, which specifies the default command line
for all Fortran versions.

F77COMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to an object file. If not set, then $F77COM or $FORTRANCOM
(the command line) is displayed.

F77FILESUFFIXES
The list of file extensions for which the F77 dialect will be used.
By default, this is ['.f77']

F77FLAGS
General user-specified options that are passed to the Fortran 77
compiler. Note that this variable does not contain -I (or similar)
include search path options that scons generates automatically from
$F77PATH. See $_F77INCFLAGS below, for the variable that expands to
those options. You only need to set $F77FLAGS if you need to define
specific user options for Fortran 77 files. You should normally set
the $FORTRANFLAGS variable, which specifies the user-specified
options passed to the default Fortran compiler for all Fortran
versions.

_F77INCFLAGS
An automatically-generated construction variable containing the
Fortran 77 compiler command-line options for specifying directories
to be searched for include files. The value of $_F77INCFLAGS is
created by appending $INCPREFIX and $INCSUFFIX to the beginning and
end of each directory in $F77PATH.

F77PATH
The list of directories that the Fortran 77 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F77FLAGS because the result will be
non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F77PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to look-up a directory relative to the
root of the source tree use #: You only need to set $F77PATH if you
need to define a specific include path for Fortran 77 files. You
should normally set the $FORTRANPATH variable, which specifies the
include path for the default Fortran compiler for all Fortran
versions.

env = Environment(F77PATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F77PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F77INCFLAGS construction variable, which
is constructed by appending the values of the $INCPREFIX and
$INCSUFFIX construction variables to the beginning and end of each
directory in $F77PATH. Any command lines you define that need the
F77PATH directory list should include $_F77INCFLAGS:

env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")

F77PPCOM
The command line used to compile a Fortran 77 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F77FLAGS and $CPPFLAGS
construction variables are included on this command line. You only
need to set $F77PPCOM if you need to use a specific C-preprocessor
command line for Fortran 77 files. You should normally set the
$FORTRANPPCOM variable, which specifies the default C-preprocessor
command line for all Fortran versions.

F77PPCOMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to an object file after first running the file through the
C preprocessor. If not set, then $F77PPCOM or $FORTRANPPCOM (the
command line) is displayed.

F77PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F77 dialect will be used. By default, this is
empty.

F90
The Fortran 90 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F90 if you need to use a
specific compiler or compiler version for Fortran 90 files.

F90COM
The command line used to compile a Fortran 90 source file to an
object file. You only need to set $F90COM if you need to use a
specific command line for Fortran 90 files. You should normally set
the $FORTRANCOM variable, which specifies the default command line
for all Fortran versions.

F90COMSTR
If set, the string displayed when a Fortran 90 source file is
compiled to an object file. If not set, then $F90COM or $FORTRANCOM
(the command line) is displayed.

F90FILESUFFIXES
The list of file extensions for which the F90 dialect will be used.
By default, this is ['.f90']

F90FLAGS
General user-specified options that are passed to the Fortran 90
compiler. Note that this variable does not contain -I (or similar)
include search path options that scons generates automatically from
$F90PATH. See $_F90INCFLAGS below, for the variable that expands to
those options. You only need to set $F90FLAGS if you need to define
specific user options for Fortran 90 files. You should normally set
the $FORTRANFLAGS variable, which specifies the user-specified
options passed to the default Fortran compiler for all Fortran
versions.

_F90INCFLAGS
An automatically-generated construction variable containing the
Fortran 90 compiler command-line options for specifying directories
to be searched for include files. The value of $_F90INCFLAGS is
created by appending $INCPREFIX and $INCSUFFIX to the beginning and
end of each directory in $F90PATH.

F90PATH
The list of directories that the Fortran 90 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F90FLAGS because the result will be
non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F90PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to look-up a directory relative to the
root of the source tree use #: You only need to set $F90PATH if you
need to define a specific include path for Fortran 90 files. You
should normally set the $FORTRANPATH variable, which specifies the
include path for the default Fortran compiler for all Fortran
versions.

env = Environment(F90PATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F90PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F90INCFLAGS construction variable, which
is constructed by appending the values of the $INCPREFIX and
$INCSUFFIX construction variables to the beginning and end of each
directory in $F90PATH. Any command lines you define that need the
F90PATH directory list should include $_F90INCFLAGS:

env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")

F90PPCOM
The command line used to compile a Fortran 90 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F90FLAGS and $CPPFLAGS
construction variables are included on this command line. You only
need to set $F90PPCOM if you need to use a specific C-preprocessor
command line for Fortran 90 files. You should normally set the
$FORTRANPPCOM variable, which specifies the default C-preprocessor
command line for all Fortran versions.

F90PPCOMSTR
If set, the string displayed when a Fortran 90 source file is
compiled after first running the file through the C preprocessor.
If not set, then $F90PPCOM or $FORTRANPPCOM (the command line) is
displayed.

F90PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F90 dialect will be used. By default, this is
empty.

F95
The Fortran 95 compiler. You should normally set the $FORTRAN
variable, which specifies the default Fortran compiler for all
Fortran versions. You only need to set $F95 if you need to use a
specific compiler or compiler version for Fortran 95 files.

F95COM
The command line used to compile a Fortran 95 source file to an
object file. You only need to set $F95COM if you need to use a
specific command line for Fortran 95 files. You should normally set
the $FORTRANCOM variable, which specifies the default command line
for all Fortran versions.

F95COMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to an object file. If not set, then $F95COM or $FORTRANCOM
(the command line) is displayed.

F95FILESUFFIXES
The list of file extensions for which the F95 dialect will be used.
By default, this is ['.f95']

F95FLAGS
General user-specified options that are passed to the Fortran 95
compiler. Note that this variable does not contain -I (or similar)
include search path options that scons generates automatically from
$F95PATH. See $_F95INCFLAGS below, for the variable that expands to
those options. You only need to set $F95FLAGS if you need to define
specific user options for Fortran 95 files. You should normally set
the $FORTRANFLAGS variable, which specifies the user-specified
options passed to the default Fortran compiler for all Fortran
versions.

_F95INCFLAGS
An automatically-generated construction variable containing the
Fortran 95 compiler command-line options for specifying directories
to be searched for include files. The value of $_F95INCFLAGS is
created by appending $INCPREFIX and $INCSUFFIX to the beginning and
end of each directory in $F95PATH.

F95PATH
The list of directories that the Fortran 95 compiler will search
for include directories. The implicit dependency scanner will
search these directories for include files. Don't explicitly put
include directory arguments in $F95FLAGS because the result will be
non-portable and the directories will not be searched by the
dependency scanner. Note: directory names in $F95PATH will be
looked-up relative to the SConscript directory when they are used
in a command. To force scons to look-up a directory relative to the
root of the source tree use #: You only need to set $F95PATH if you
need to define a specific include path for Fortran 95 files. You
should normally set the $FORTRANPATH variable, which specifies the
include path for the default Fortran compiler for all Fortran
versions.

env = Environment(F95PATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(F95PATH=include)

The directory list will be added to command lines through the
automatically-generated $_F95INCFLAGS construction variable, which
is constructed by appending the values of the $INCPREFIX and
$INCSUFFIX construction variables to the beginning and end of each
directory in $F95PATH. Any command lines you define that need the
F95PATH directory list should include $_F95INCFLAGS:

env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")

F95PPCOM
The command line used to compile a Fortran 95 source file to an
object file after first running the file through the C
preprocessor. Any options specified in the $F95FLAGS and $CPPFLAGS
construction variables are included on this command line. You only
need to set $F95PPCOM if you need to use a specific C-preprocessor
command line for Fortran 95 files. You should normally set the
$FORTRANPPCOM variable, which specifies the default C-preprocessor
command line for all Fortran versions.

F95PPCOMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to an object file after first running the file through the
C preprocessor. If not set, then $F95PPCOM or $FORTRANPPCOM (the
command line) is displayed.

F95PPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for F95 dialect will be used. By default, this is
empty.

File
A function that converts a string into a File instance relative to
the target being built.

FORTRAN
The default Fortran compiler for all versions of Fortran.

FORTRANCOM
The command line used to compile a Fortran source file to an object
file. By default, any options specified in the $FORTRANFLAGS,
$_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are
included on this command line.

FORTRANCOMMONFLAGS
General user-specified options that are passed to the Fortran
compiler. Similar to $FORTRANFLAGS, but this variable is applied to
all dialects.

FORTRANCOMSTR
If set, the string displayed when a Fortran source file is compiled
to an object file. If not set, then $FORTRANCOM (the command line)
is displayed.

FORTRANFILESUFFIXES
The list of file extensions for which the FORTRAN dialect will be
used. By default, this is ['.f', '.for', '.ftn']

FORTRANFLAGS
General user-specified options for the FORTRAN dialect that are
passed to the Fortran compiler. Note that this variable does not
contain -I (or similar) include or module search path options that
scons generates automatically from $FORTRANPATH. See
$_FORTRANINCFLAGS and $_FORTRANMODFLAG, below, for the variables
that expand those options.

_FORTRANINCFLAGS
An automatically-generated construction variable containing the
Fortran compiler command-line options for specifying directories to
be searched for include files and module files. The value of
$_FORTRANINCFLAGS is created by respectively prepending and
appending $INCPREFIX and $INCSUFFIX to the beginning and end of
each directory in $FORTRANPATH.

FORTRANMODDIR
Directory location where the Fortran compiler should place any
module files it generates. This variable is empty, by default. Some
Fortran compilers will internally append this directory in the
search path for module files, as well.

FORTRANMODDIRPREFIX
The prefix used to specify a module directory on the Fortran
compiler command line. This will be prepended to the beginning of
the directory in the $FORTRANMODDIR construction variables when the
$_FORTRANMODFLAG variables is automatically generated.

FORTRANMODDIRSUFFIX
The suffix used to specify a module directory on the Fortran
compiler command line. This will be appended to the end of the
directory in the $FORTRANMODDIR construction variables when the
$_FORTRANMODFLAG variables is automatically generated.

_FORTRANMODFLAG
An automatically-generated construction variable containing the
Fortran compiler command-line option for specifying the directory
location where the Fortran compiler should place any module files
that happen to get generated during compilation. The value of
$_FORTRANMODFLAG is created by respectively prepending and
appending $FORTRANMODDIRPREFIX and $FORTRANMODDIRSUFFIX to the
beginning and end of the directory in $FORTRANMODDIR.

FORTRANMODPREFIX
The module file prefix used by the Fortran compiler. SCons assumes
that the Fortran compiler follows the quasi-standard naming
convention for module files of module_name.mod. As a result, this
variable is left empty, by default. For situations in which the
compiler does not necessarily follow the normal convention, the
user may use this variable. Its value will be appended to every
module file name as scons attempts to resolve dependencies.

FORTRANMODSUFFIX
The module file suffix used by the Fortran compiler. SCons assumes
that the Fortran compiler follows the quasi-standard naming
convention for module files of module_name.mod. As a result, this
variable is set to ".mod", by default. For situations in which the
compiler does not necessarily follow the normal convention, the
user may use this variable. Its value will be appended to every
module file name as scons attempts to resolve dependencies.

FORTRANPATH
The list of directories that the Fortran compiler will search for
include files and (for some compilers) module files. The Fortran
implicit dependency scanner will search these directories for
include files (but not module files since they are autogenerated
and, as such, may not actually exist at the time the scan takes
place). Don't explicitly put include directory arguments in
FORTRANFLAGS because the result will be non-portable and the
directories will not be searched by the dependency scanner. Note:
directory names in FORTRANPATH will be looked-up relative to the
SConscript directory when they are used in a command. To force
scons to look-up a directory relative to the root of the source
tree use #:

env = Environment(FORTRANPATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(FORTRANPATH=include)

The directory list will be added to command lines through the
automatically-generated $_FORTRANINCFLAGS construction variable,
which is constructed by respectively prepending and appending the
values of the $INCPREFIX and $INCSUFFIX construction variables to
the beginning and end of each directory in $FORTRANPATH. Any
command lines you define that need the FORTRANPATH directory list
should include $_FORTRANINCFLAGS:

env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")

FORTRANPPCOM
The command line used to compile a Fortran source file to an object
file after first running the file through the C preprocessor. By
default, any options specified in the $FORTRANFLAGS, $CPPFLAGS,
$_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction
variables are included on this command line.

FORTRANPPCOMSTR
If set, the string displayed when a Fortran source file is compiled
to an object file after first running the file through the C
preprocessor. If not set, then $FORTRANPPCOM (the command line) is
displayed.

FORTRANPPFILESUFFIXES
The list of file extensions for which the compilation +
preprocessor pass for FORTRAN dialect will be used. By default,
this is ['.fpp', '.FPP']

FORTRANSUFFIXES
The list of suffixes of files that will be scanned for Fortran
implicit dependencies (INCLUDE lines and USE statements). The
default list is:

[".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP",
".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]

FRAMEWORKPATH
On Mac OS X with gcc, a list containing the paths to search for
frameworks. Used by the compiler to find framework-style includes
like #include <Fmwk/Header.h>. Used by the linker to find
user-specified frameworks when linking (see $FRAMEWORKS). For
example:

env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')

will add

... -Fmyframeworkdir

to the compiler and linker command lines.

_FRAMEWORKPATH
On Mac OS X with gcc, an automatically-generated construction
variable containing the linker command-line options corresponding
to $FRAMEWORKPATH.

FRAMEWORKPATHPREFIX
On Mac OS X with gcc, the prefix to be used for the FRAMEWORKPATH
entries. (see $FRAMEWORKPATH). The default value is -F.

FRAMEWORKPREFIX
On Mac OS X with gcc, the prefix to be used for linking in
frameworks (see $FRAMEWORKS). The default value is -framework.

FRAMEWORKS
On Mac OS X with gcc, a list of the framework names to be linked
into a program or shared library or bundle. The default value is
the empty list. For example:

env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))

_FRAMEWORKS
On Mac OS X with gcc, an automatically-generated construction
variable containing the linker command-line options for linking
with FRAMEWORKS.

FRAMEWORKSFLAGS
On Mac OS X with gcc, general user-supplied frameworks options to
be added at the end of a command line building a loadable module.
(This has been largely superseded by the $FRAMEWORKPATH,
$FRAMEWORKPATHPREFIX, $FRAMEWORKPREFIX and $FRAMEWORKS variables
described above.)

GS
The Ghostscript program used to, for example, convert PostScript to
PDF files.

GSCOM
The full Ghostscript command line used for the conversion process.
Its default value is “$GS $GSFLAGS -sOutputFile=$TARGET $SOURCES”.

GSCOMSTR
The string displayed when Ghostscript is called for the conversion
process. If this is not set (the default), then $GSCOM (the command
line) is displayed.

GSFLAGS
General options passed to the Ghostscript program, when converting
PostScript to PDF files for example. Its default value is
“-dNOPAUSE -dBATCH -sDEVICE=pdfwrite”

HOST_ARCH
The name of the host hardware architecture used to create this
construction environment. The platform code sets this when
initializing (see $PLATFORM and the platform argument to
Environment). Note the detected name of the architecture may not be
identical to that returned by the Python platform.machine method.

On the win32 platform, if the Microsoft Visual C++ compiler is
available, msvc tool setup is done using $HOST_ARCH and
$TARGET_ARCH. Changing the values at any later time will not cause
the tool to be reinitialized. Valid host arch values are x86 and
arm for 32-bit hosts and amd64 and x86_64 for 64-bit hosts.

Should be considered immutable. $HOST_ARCH is not currently used
by other platforms, but the option is reserved to do so in future

HOST_OS
The name of the host operating system for the platform used to
create this construction environment. The platform code sets this
when initializing (see $PLATFORM and the platform argument to
Environment).

Should be considered immutable. $HOST_OS is not currently used by
SCons, but the option is reserved to do so in future

IDLSUFFIXES
The list of suffixes of files that will be scanned for IDL implicit
dependencies (#include or import lines). The default list is:

[".idl", ".IDL"]

IMPLIBNOVERSIONSYMLINKS
Used to override $SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS
when creating versioned import library for a shared
library/loadable module. If not defined, then
$SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS is used to
determine whether to disable symlink generation or not.

IMPLIBPREFIX
The prefix used for import library names. For example, cygwin uses
import libraries (libfoo.dll.a) in pair with dynamic libraries
(cygfoo.dll). The cyglink linker sets $IMPLIBPREFIX to 'lib' and
$SHLIBPREFIX to 'cyg'.

IMPLIBSUFFIX
The suffix used for import library names. For example, cygwin uses
import libraries (libfoo.dll.a) in pair with dynamic libraries
(cygfoo.dll). The cyglink linker sets $IMPLIBSUFFIX to '.dll.a' and
$SHLIBSUFFIX to '.dll'.

IMPLIBVERSION
Used to override $SHLIBVERSION/$LDMODULEVERSION when generating
versioned import library for a shared library/loadable module. If
undefined, the $SHLIBVERSION/$LDMODULEVERSION is used to determine
the version of versioned import library.

IMPLICIT_COMMAND_DEPENDENCIES
Controls whether or not SCons will add implicit dependencies for
the commands executed to build targets.

By default, SCons will add to each target an implicit dependency on
the command represented by the first argument of any command line
it executes (which is typically the command itself). By setting
such a dependency, SCons can determine that a target should be
rebuilt if the command changes, such as when a compiler is upgraded
to a new version. The specific file for the dependency is found by
searching the PATH variable in the ENV dictionary in the
construction environment used to execute the command. The default
is the same as setting the construction variable
$IMPLICIT_COMMAND_DEPENDENCIES to a True-like value (“true”, “yes”,
or “1” - but not a number greater than one, as that has a different
meaning).

Action strings can be segmented by the use of an AND operator, &&.
In a segemented string, each segment is a separate “command line”,
these are run sequentially until one fails or the entire sequence
has been executed. If an action string is segmented, then the
selected behavior of $IMPLICIT_COMMAND_DEPENDENCIES is applied to
each segment.

If $IMPLICIT_COMMAND_DEPENDENCIES is set to a False-like value
(“none”, “false”, “no”, “0”, etc.), then the implicit dependency
will not be added to the targets built with that construction
environment.

If $IMPLICIT_COMMAND_DEPENDENCIES is set to “2” or higher, then
that number of arguments in the command line will be scanned for
relative or absolute paths. If any are present, they will be added
as implicit dependencies to the targets built with that
construction environment. The first argument in the command line
will be searched for using the PATH variable in the ENV dictionary
in the construction environment used to execute the command. The
other arguments will only be found if they are absolute paths or
valid paths relative to the working directory.

If $IMPLICIT_COMMAND_DEPENDENCIES is set to “all”, then all
arguments in the command line will be scanned for relative or
absolute paths. If any are present, they will be added as implicit
dependencies to the targets built with that construction
environment. The first argument in the command line will be
searched for using the PATH variable in the ENV dictionary in the
construction environment used to execute the command. The other
arguments will only be found if they are absolute paths or valid
paths relative to the working directory.

env = Environment(IMPLICIT_COMMAND_DEPENDENCIES=False)

INCPREFIX
The prefix used to specify an include directory on the C compiler
command line. This will be prepended to each directory in the
$CPPPATH and $FORTRANPATH construction variables when the
$_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically
generated.

INCSUFFIX
The suffix used to specify an include directory on the C compiler
command line. This will be appended to each directory in the
$CPPPATH and $FORTRANPATH construction variables when the
$_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically
generated.

INSTALL
A function to be called to install a file into a destination file
name. The default function copies the file into the destination
(and sets the destination file's mode and permission bits to match
the source file's). The function takes the following arguments:

def install(dest, source, env):

dest is the path name of the destination file. source is the path
name of the source file. env is the construction environment (a
dictionary of construction values) in force for this file
installation.

INSTALLSTR
The string displayed when a file is installed into a destination
file name. The default is:

Install file: "$SOURCE" as "$TARGET"

INTEL_C_COMPILER_VERSION
Set by the intelc Tool to the major version number of the Intel C
compiler selected for use.

JAR
The Java archive tool.

JARCHDIR
The directory to which the Java archive tool should change (using
the -C option).

JARCOM
The command line used to call the Java archive tool.

JARCOMSTR
The string displayed when the Java archive tool is called If this
is not set, then $JARCOM (the command line) is displayed.

env = Environment(JARCOMSTR="JARchiving $SOURCES into $TARGET")

JARFLAGS
General options passed to the Java archive tool. By default this is
set to cf to create the necessary jar file.

JARSUFFIX
The suffix for Java archives: .jar by default.

JAVABOOTCLASSPATH
Specifies the list of directories that will be added to the javac
command line via the -bootclasspath option. The individual
directory names will be separated by the operating system's path
separate character (: on UNIX/Linux/POSIX, ; on Windows).

JAVAC
The Java compiler.

JAVACCOM
The command line used to compile a directory tree containing Java
source files to corresponding Java class files. Any options
specified in the $JAVACFLAGS construction variable are included on
this command line.

JAVACCOMSTR
The string displayed when compiling a directory tree of Java source
files to corresponding Java class files. If this is not set, then
$JAVACCOM (the command line) is displayed.

env = Environment(JAVACCOMSTR="Compiling class files $TARGETS from $SOURCES")

JAVACFLAGS
General options that are passed to the Java compiler.

JAVACLASSDIR
The directory in which Java class files may be found. This is
stripped from the beginning of any Java .class file names supplied
to the JavaH builder.

JAVACLASSPATH
Specifies the list of directories that will be searched for Java
.class file. The directories in this list will be added to the
javac and javah command lines via the -classpath option. The
individual directory names will be separated by the operating
system's path separate character (: on UNIX/Linux/POSIX, ; on
Windows).

JAVACLASSSUFFIX
The suffix for Java class files; .class by default.

JAVAH
The Java generator for C header and stub files.

JAVAHCOM
The command line used to generate C header and stub files from Java
classes. Any options specified in the $JAVAHFLAGS construction
variable are included on this command line.

JAVAHCOMSTR
The string displayed when C header and stub files are generated
from Java classes. If this is not set, then $JAVAHCOM (the command
line) is displayed.

env = Environment(JAVAHCOMSTR="Generating header/stub file(s) $TARGETS from $SOURCES")

JAVAHFLAGS
General options passed to the C header and stub file generator for
Java classes.

JAVAINCLUDES
Include path for Java header files (such as jni.h)

JAVASOURCEPATH
Specifies the list of directories that will be searched for input
.java file. The directories in this list will be added to the javac
command line via the -sourcepath option. The individual directory
names will be separated by the operating system's path separate
character (: on UNIX/Linux/POSIX, ; on Windows).

Note that this currently just adds the specified directory via the
-sourcepath option. SCons does not currently search the
$JAVASOURCEPATH directories for dependency .java files.

JAVASUFFIX
The suffix for Java files; .java by default.

JAVAVERSION
Specifies the Java version being used by the Java builder. Set this
to specify the version of Java targeted by the javac compiler. This
is sometimes necessary because Java 1.5 changed the file names that
are created for nested anonymous inner classes, which can cause a
mismatch with the files that SCons expects will be generated by the
javac compiler. Setting $JAVAVERSION to a version greater than 1.4
makes SCons realize that a build with such a compiler is actually
up to date. The default is 1.4.

While this is not primarily intended for selecting one version of
the Java compiler vs. another, it does have that effect on the
Windows platform. A more precise approach is to set $JAVAC (and
related construction variables for related utilities) to the path
to the specific Java compiler you want, if that is not the default
compiler. On non-Windows platforms, the alternatives system may
provide a way to adjust the default Java compiler without having to
specify explicit paths.

LATEX
The LaTeX structured formatter and typesetter.

LATEXCOM
The command line used to call the LaTeX structured formatter and
typesetter.

LATEXCOMSTR
The string displayed when calling the LaTeX structured formatter
and typesetter. If this is not set, then $LATEXCOM (the command
line) is displayed.

env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")

LATEXFLAGS
General options passed to the LaTeX structured formatter and
typesetter.

LATEXRETRIES
The maximum number of times that LaTeX will be re-run if the .log
generated by the $LATEXCOM command indicates that there are
undefined references. The default is to try to resolve undefined
references by re-running LaTeX up to three times.

LATEXSUFFIXES
The list of suffixes of files that will be scanned for LaTeX
implicit dependencies (\include or \import files). The default list
is:

[".tex", ".ltx", ".latex"]

LDMODULE
The linker for building loadable modules. By default, this is the
same as $SHLINK.

LDMODULECOM
The command line for building loadable modules. On Mac OS X, this
uses the $LDMODULE, $LDMODULEFLAGS and $FRAMEWORKSFLAGS variables.
On other systems, this is the same as $SHLINK.

LDMODULECOMSTR
If set, the string displayed when building loadable modules. If not
set, then $LDMODULECOM (the command line) is displayed.

LDMODULEEMITTER
Contains the emitter specification for the LoadableModule builder.
The manpage section "Builder Objects" contains general information
on specifying emitters.

LDMODULEFLAGS
General user options passed to the linker for building loadable
modules.

LDMODULENOVERSIONSYMLINKS
Instructs the LoadableModule builder to not automatically create
symlinks for versioned modules. Defaults to $SHLIBNOVERSIONSYMLINKS

LDMODULEPREFIX
The prefix used for loadable module file names. On Mac OS X, this
is null; on other systems, this is the same as $SHLIBPREFIX.

_LDMODULESONAME
A macro that automatically generates loadable module's SONAME based
on $TARGET, $LDMODULEVERSION and $LDMODULESUFFIX. Used by
LoadableModule builder when the linker tool supports SONAME (e.g.
gnulink).

LDMODULESUFFIX
The suffix used for loadable module file names. On Mac OS X, this
is null; on other systems, this is the same as $SHLIBSUFFIX.

LDMODULEVERSION
When this construction variable is defined, a versioned loadable
module is created by LoadableModule builder. This activates the
$_LDMODULEVERSIONFLAGS and thus modifies the $LDMODULECOM as
required, adds the version number to the library name, and creates
the symlinks that are needed. $LDMODULEVERSION versions should
exist in the same format as $SHLIBVERSION.

_LDMODULEVERSIONFLAGS
This macro automatically introduces extra flags to $LDMODULECOM
when building versioned LoadableModule (that is when
$LDMODULEVERSION is set). _LDMODULEVERSIONFLAGS usually adds
$SHLIBVERSIONFLAGS and some extra dynamically generated options
(such as -Wl,-soname=$_LDMODULESONAME). It is unused by plain
(unversioned) loadable modules.

LDMODULEVERSIONFLAGS
Extra flags added to $LDMODULECOM when building versioned
LoadableModule. These flags are only used when $LDMODULEVERSION is
set.

LEX
The lexical analyzer generator.

LEX_HEADER_FILE
If supplied, generate a C header file with the name taken from this
variable. Will be emitted as a --header-file= command-line option.
Use this in preference to including --header-file= in $LEXFLAGS
directly.

LEX_TABLES_FILE
If supplied, write the lex tables to a file with the name taken
from this variable. Will be emitted as a --tables-file=
command-line option. Use this in preference to including
--tables-file= in $LEXFLAGS directly.

LEXCOM
The command line used to call the lexical analyzer generator to
generate a source file.

LEXCOMSTR
The string displayed when generating a source file using the
lexical analyzer generator. If this is not set, then $LEXCOM (the
command line) is displayed.

env = Environment(LEXCOMSTR="Lex'ing $TARGET from $SOURCES")

LEXFLAGS
General options passed to the lexical analyzer generator. In
addition to passing the value on during invocation, the lex tool
also examines this construction variable for options which cause
additional output files to be generated, and adds those to the
target list. Recognized for this purpose are GNU flex options
--header-file= and --tables-file=; the output file is named by the
option argument.

Note that files specified by --header-file= and --tables-file= may
not be properly handled by SCons in all situations. Consider using
$LEX_HEADER_FILE and $LEX_TABLES_FILE instead.

LEXUNISTD
Used only on windows environments to set a lex flag to prevent
'unistd.h' from being included. The default value is '--nounistd'.

_LIBDIRFLAGS
An automatically-generated construction variable containing the
linker command-line options for specifying directories to be
searched for library. The value of $_LIBDIRFLAGS is created by
respectively prepending and appending $LIBDIRPREFIX and
$LIBDIRSUFFIX to each directory in $LIBPATH.

LIBDIRPREFIX
The prefix used to specify a library directory on the linker
command line. This will be prepended to each directory in the
$LIBPATH construction variable when the $_LIBDIRFLAGS variable is
automatically generated.

LIBDIRSUFFIX
The suffix used to specify a library directory on the linker
command line. This will be appended to each directory in the
$LIBPATH construction variable when the $_LIBDIRFLAGS variable is
automatically generated.

LIBEMITTER
Contains the emitter specification for the StaticLibrary builder.
The manpage section "Builder Objects" contains general information
on specifying emitters.

_LIBFLAGS
An automatically-generated construction variable containing the
linker command-line options for specifying libraries to be linked
with the resulting target. The value of $_LIBFLAGS is created by
respectively prepending and appending $LIBLINKPREFIX and
$LIBLINKSUFFIX to each filename in $LIBS.

LIBLINKPREFIX
The prefix used to specify a library to link on the linker command
line. This will be prepended to each library in the $LIBS
construction variable when the $_LIBFLAGS variable is automatically
generated.

LIBLINKSUFFIX
The suffix used to specify a library to link on the linker command
line. This will be appended to each library in the $LIBS
construction variable when the $_LIBFLAGS variable is automatically
generated.

LIBPATH
The list of directories that will be searched for libraries
specified by the $LIBS construction variable. $LIBPATH should be a
list of path strings, or a single string, not a pathname list
joined by Python's os.sep.

Do not put library search directives directly into $LINKFLAGS or
$SHLINKFLAGS as the result will be non-portable.

Note: directory names in $LIBPATH will be looked-up relative to the
directory of the SConscript file when they are used in a command.
To force scons to look-up a directory relative to the root of the
source tree use the # prefix:

env = Environment(LIBPATH='#/libs')

The directory look-up can also be forced using the Dir function:

libs = Dir('libs')
env = Environment(LIBPATH=libs)

The directory list will be added to command lines through the
automatically-generated $_LIBDIRFLAGS construction variable, which
is constructed by respectively prepending and appending the values
of the $LIBDIRPREFIX and $LIBDIRSUFFIX construction variables to
each directory in $LIBPATH. Any command lines you define that need
the $LIBPATH directory list should include $_LIBDIRFLAGS:

env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

LIBPREFIX
The prefix used for (static) library file names. A default value is
set for each platform (posix, win32, os2, etc.), but the value is
overridden by individual tools (ar, mslib, sgiar, sunar, tlib,
etc.) to reflect the names of the libraries they create.

LIBPREFIXES
A list of all legal prefixes for library file names. When searching
for library dependencies, SCons will look for files with these
prefixes, the base library name, and suffixes from the $LIBSUFFIXES
list.

LIBS
A list of one or more libraries that will be added to the link line
for linking with any executable program, shared library, or
loadable module created by the construction environment or
override.

String-valued library names should include only the library base
names, without prefixes such as lib or suffixes such as .so or
.dll. The library list will be added to command lines through the
automatically-generated $_LIBFLAGS construction variable which is
constructed by respectively prepending and appending the values of
the $LIBLINKPREFIX and $LIBLINKSUFFIX construction variables to
each library name in $LIBS. Library name strings should not include
a path component, instead the compiler will be directed to look for
libraries in the paths specified by $LIBPATH.

Any command lines you define that need the $LIBS library list
should include $_LIBFLAGS:

env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

If you add a File object to the $LIBS list, the name of that file
will be added to $_LIBFLAGS, and thus to the link line, as-is,
without $LIBLINKPREFIX or $LIBLINKSUFFIX. For example:

env.Append(LIBS=File('/tmp/mylib.so'))

In all cases, scons will add dependencies from the executable
program to all the libraries in this list.

LIBSUFFIX
The suffix used for (static) library file names. A default value is
set for each platform (posix, win32, os2, etc.), but the value is
overridden by individual tools (ar, mslib, sgiar, sunar, tlib,
etc.) to reflect the names of the libraries they create.

LIBSUFFIXES
A list of all legal suffixes for library file names. When searching
for library dependencies, SCons will look for files with prefixes
from the $LIBPREFIXES list, the base library name, and these
suffixes.

LICENSE
The abbreviated name, preferably the SPDX code, of the license
under which this project is released (GPL-3.0, LGPL-2.1,
BSD-2-Clause etc.). See
http://www.opensource.org/licenses/alphabetical[5] for a list of
license names and SPDX codes.

See the Package builder.

LINESEPARATOR
The separator used by the Substfile and Textfile builders. This
value is used between sources when constructing the target. It
defaults to the current system line separator.

LINGUAS_FILE
The $LINGUAS_FILE defines file(s) containing list of additional
linguas to be processed by POInit, POUpdate or MOFiles builders. It
also affects Translate builder. If the variable contains a string,
it defines name of the list file. The $LINGUAS_FILE may be a list
of file names as well. If $LINGUAS_FILE is set to True (or non-zero
numeric value), the list will be read from default file named
LINGUAS.

LINK
The linker. See also $SHLINK for linking shared objects.

On POSIX systems (those using the link tool), you should normally
not change this value as it defaults to a "smart" linker tool which
selects a compiler driver matching the type of source files in use.
So for example, if you set $CXX to a specific compiler name, and
are compiling C++ sources, the smartlink function will
automatically select the same compiler for linking.

LINKCOM
The command line used to link object files into an executable. See
also $SHLINKCOM for linking shared objects.

LINKCOMSTR
If set, the string displayed when object files are linked into an
executable. If not set, then $LINKCOM (the command line) is
displayed. See also $SHLINKCOMSTR. for linking shared objects.

env = Environment(LINKCOMSTR = "Linking $TARGET")

LINKFLAGS
General user options passed to the linker. Note that this variable
should not contain -l (or similar) options for linking with the
libraries listed in $LIBS, nor -L (or similar) library search path
options that scons generates automatically from $LIBPATH. See
$_LIBFLAGS above, for the variable that expands to library-link
options, and $_LIBDIRFLAGS above, for the variable that expands to
library search path options. See also $SHLINKFLAGS. for linking
shared objects.

M4
The M4 macro preprocessor.

M4COM
The command line used to pass files through the M4 macro
preprocessor.

M4COMSTR
The string displayed when a file is passed through the M4 macro
preprocessor. If this is not set, then $M4COM (the command line) is
displayed.

M4FLAGS
General options passed to the M4 macro preprocessor.

MAKEINDEX
The makeindex generator for the TeX formatter and typesetter and
the LaTeX structured formatter and typesetter.

MAKEINDEXCOM
The command line used to call the makeindex generator for the TeX
formatter and typesetter and the LaTeX structured formatter and
typesetter.

MAKEINDEXCOMSTR
The string displayed when calling the makeindex generator for the
TeX formatter and typesetter and the LaTeX structured formatter and
typesetter. If this is not set, then $MAKEINDEXCOM (the command
line) is displayed.

MAKEINDEXFLAGS
General options passed to the makeindex generator for the TeX
formatter and typesetter and the LaTeX structured formatter and
typesetter.

MAXLINELENGTH
The maximum number of characters allowed on an external command
line. On Win32 systems, link lines longer than this many characters
are linked via a temporary file name.

MIDL
The Microsoft IDL compiler.

MIDLCOM
The command line used to pass files to the Microsoft IDL compiler.

MIDLCOMSTR
The string displayed when the Microsoft IDL compiler is called. If
this is not set, then $MIDLCOM (the command line) is displayed.

MIDLFLAGS
General options passed to the Microsoft IDL compiler.

MOSUFFIX
Suffix used for MO files (default: '.mo'). See msgfmt tool and
MOFiles builder.

MSGFMT
Absolute path to msgfmt(1) binary, found by Detect(). See msgfmt
tool and MOFiles builder.

MSGFMTCOM
Complete command line to run msgfmt(1) program. See msgfmt tool and
MOFiles builder.

MSGFMTCOMSTR
String to display when msgfmt(1) is invoked (default: '', which
means ``print $MSGFMTCOM''). See msgfmt tool and MOFiles builder.

MSGFMTFLAGS
Additional flags to msgfmt(1). See msgfmt tool and MOFiles builder.

MSGINIT
Path to msginit(1) program (found via Detect()). See msginit tool
and POInit builder.

MSGINITCOM
Complete command line to run msginit(1) program. See msginit tool
and POInit builder.

MSGINITCOMSTR
String to display when msginit(1) is invoked (default: '', which
means ``print $MSGINITCOM''). See msginit tool and POInit builder.

MSGINITFLAGS
List of additional flags to msginit(1) (default: []). See msginit
tool and POInit builder.

_MSGINITLOCALE
Internal ``macro''. Computes locale (language) name based on target
filename (default: '${TARGET.filebase}').

See msginit tool and POInit builder.

MSGMERGE
Absolute path to msgmerge(1) binary as found by Detect(). See
msgmerge tool and POUpdate builder.

MSGMERGECOM
Complete command line to run msgmerge(1) command. See msgmerge tool
and POUpdate builder.

MSGMERGECOMSTR
String to be displayed when msgmerge(1) is invoked (default: '',
which means ``print $MSGMERGECOM''). See msgmerge tool and POUpdate
builder.

MSGMERGEFLAGS
Additional flags to msgmerge(1) command. See msgmerge tool and
POUpdate builder.

MSSDK_DIR
The directory containing the Microsoft SDK (either Platform SDK or
Windows SDK) to be used for compilation.

MSSDK_VERSION
The version string of the Microsoft SDK (either Platform SDK or
Windows SDK) to be used for compilation. Supported versions include
6.1, 6.0A, 6.0, 2003R2 and 2003R1.

MSVC_BATCH
When set to any true value, specifies that SCons should batch
compilation of object files when calling the Microsoft Visual C/C++
compiler. All compilations of source files from the same source
directory that generate target files in a same output directory and
were configured in SCons using the same construction environment
will be built in a single call to the compiler. Only source files
that have changed since their object files were built will be
passed to each compiler invocation (via the $CHANGED_SOURCES
construction variable). Any compilations where the object (target)
file base name (minus the .obj) does not match the source file base
name will be compiled separately.

MSVC_NOTFOUND_POLICY
Specify the scons behavior when the Microsoft Visual C/C++ compiler
is not detected.

The $MSVC_NOTFOUND_POLICY specifies the scons behavior when no msvc
versions are detected or when the requested msvc version is not
detected.

The valid values for $MSVC_NOTFOUND_POLICY and the corresponding
scons behavior are:

'Error' or 'Exception'
Raise an exception when no msvc versions are detected or when
the requested msvc version is not detected.

'Warning' or 'Warn'
Issue a warning and continue when no msvc versions are detected
or when the requested msvc version is not detected. Depending
on usage, this could result in build failure(s).

'Ignore' or 'Suppress'
Take no action and continue when no msvc versions are detected
or when the requested msvc version is not detected. Depending
on usage, this could result in build failure(s).

Note: in addition to the camel case values shown above, lower case
and upper case values are accepted as well.

The $MSVC_NOTFOUND_POLICY is applied when any of the following
conditions are satisfied:

• $MSVC_VERSION is specified, the default tools list is
implicitly defined (i.e., the tools list is not specified), and
the default tools list contains one or more of the msvc tools.

• $MSVC_VERSION is specified, the default tools list is
explicitly specified (e.g., tools=['default']), and the default
tools list contains one or more of the msvc tools.

• A non-default tools list is specified that contains one or more
of the msvc tools (e.g., tools=['msvc', 'mslink']).

The $MSVC_NOTFOUND_POLICY is ignored when any of the following
conditions are satisfied:

• $MSVC_VERSION is not specified and the default tools list is
implicitly defined (i.e., the tools list is not specified).

• $MSVC_VERSION is not specified and the default tools list is
explicitly specified (e.g., tools=['default']).

• A non-default tool list is specified that does not contain any
of the msvc tools (e.g., tools=['mingw']).

Important usage details:

• $MSVC_NOTFOUND_POLICY must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_NOTFOUND_POLICY must be set before the first msvc tool is
loaded into the environment.

When $MSVC_NOTFOUND_POLICY is not specified, the default scons
behavior is to issue a warning and continue subject to the
conditions listed above. The default scons behavior may change in
the future.

MSVC_SCRIPT_ARGS
Pass user-defined arguments to the Visual C++ batch file determined
via autodetection.

$MSVC_SCRIPT_ARGS is available for msvc batch file arguments that
do not have first-class support via construction variables or when
there is an issue with the appropriate construction variable
validation. When available, it is recommended to use the
appropriate construction variables (e.g., $MSVC_TOOLSET_VERSION)
rather than $MSVC_SCRIPT_ARGS arguments.

The valid values for $MSVC_SCRIPT_ARGS are: None, a string, or a
list of strings.

The $MSVC_SCRIPT_ARGS value is converted to a scalar string (i.e.,
"flattened"). The resulting scalar string, if not empty, is passed
as an argument to the msvc batch file determined via autodetection
subject to the validation conditions listed below.

$MSVC_SCRIPT_ARGS is ignored when the value is None and when the
result from argument conversion is an empty string. The validation
conditions below do not apply.

An exception is raised when any of the following conditions are
satisfied:

• $MSVC_SCRIPT_ARGS is specified for Visual Studio 2013 and
earlier.

• Multiple SDK version arguments (e.g., '10.0.20348.0') are
specified in $MSVC_SCRIPT_ARGS.

• $MSVC_SDK_VERSION is specified and an SDK version argument
(e.g., '10.0.20348.0') is specified in $MSVC_SCRIPT_ARGS.
Multiple SDK version declarations via $MSVC_SDK_VERSION and
$MSVC_SCRIPT_ARGS are not allowed.

• Multiple toolset version arguments (e.g., '-vcvars_ver=14.29')
are specified in $MSVC_SCRIPT_ARGS.

• $MSVC_TOOLSET_VERSION is specified and a toolset version
argument (e.g., '-vcvars_ver=14.29') is specified in
$MSVC_SCRIPT_ARGS. Multiple toolset version declarations via
$MSVC_TOOLSET_VERSION and $MSVC_SCRIPT_ARGS are not allowed.

• Multiple spectre library arguments (e.g.,
'-vcvars_spectre_libs=spectre') are specified in
$MSVC_SCRIPT_ARGS.

• $MSVC_SPECTRE_LIBS is enabled and a spectre library argument
(e.g., '-vcvars_spectre_libs=spectre') is specified in
$MSVC_SCRIPT_ARGS. Multiple spectre library declarations via
$MSVC_SPECTRE_LIBS and $MSVC_SCRIPT_ARGS are not allowed.

• Multiple UWP arguments (e.g., uwp or store) are specified in
$MSVC_SCRIPT_ARGS.

• $MSVC_UWP_APP is enabled and a UWP argument (e.g., uwp or
store) is specified in $MSVC_SCRIPT_ARGS. Multiple UWP
declarations via $MSVC_UWP_APP and $MSVC_SCRIPT_ARGS are not
allowed.

Example 1 - A Visual Studio 2022 build with an SDK version and a
toolset version specified with a string argument:

env = Environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS='10.0.20348.0 -vcvars_ver=14.29.30133')

Example 2 - A Visual Studio 2022 build with an SDK version and a
toolset version specified with a list argument:

env = Environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['10.0.20348.0', '-vcvars_ver=14.29.30133'])

Important usage details:

• $MSVC_SCRIPT_ARGS must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_SCRIPT_ARGS must be set before the first msvc tool is
loaded into the environment.

• Other than checking for multiple declarations as described
above, $MSVC_SCRIPT_ARGS arguments are not validated.

•
Erroneous, inconsistent, and/or version incompatible
$MSVC_SCRIPT_ARGS arguments are likely to result in build
failures for reasons that are not readily apparent and may be
difficult to diagnose. The burden is on the user to ensure
that the arguments provided to the msvc batch file are valid,
consistent and compatible with the version of msvc selected.

MSVC_SCRIPTERROR_POLICY
Specify the scons behavior when Microsoft Visual C/C++ batch file
errors are detected.

The $MSVC_SCRIPTERROR_POLICY specifies the scons behavior when msvc
batch file errors are detected. When $MSVC_SCRIPTERROR_POLICY is
not specified, the default scons behavior is to suppress msvc batch
file error messages.

The root cause of msvc build failures may be difficult to diagnose.
In these situations, setting the scons behavior to issue a warning
when msvc batch file errors are detected may produce additional
diagnostic information.

The valid values for $MSVC_SCRIPTERROR_POLICY and the corresponding
scons behavior are:

'Error' or 'Exception'
Raise an exception when msvc batch file errors are detected.

'Warning' or 'Warn'
Issue a warning when msvc batch file errors are detected.

'Ignore' or 'Suppress'
Suppress msvc batch file error messages.

Note: in addition to the camel case values shown above, lower case
and upper case values are accepted as well.

Example 1 - A Visual Studio 2022 build with user-defined script
arguments:

env = environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['8.1', 'store', '-vcvars_ver=14.1'])
env.Program('hello', ['hello.c'], CCFLAGS='/MD', LIBS=['kernel32', 'user32', 'runtimeobject'])

Example 1 - Output fragment:

...
link /nologo /OUT:_build001\hello.exe kernel32.lib user32.lib runtimeobject.lib _build001\hello.obj
LINK : fatal error LNK1104: cannot open file 'MSVCRT.lib'
...

Example 2 - A Visual Studio 2022 build with user-defined script
arguments and the script error policy set to issue a warning when
msvc batch file errors are detected:

env = environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['8.1', 'store', '-vcvars_ver=14.1'], MSVC_SCRIPTERROR_POLICY='warn')
env.Program('hello', ['hello.c'], CCFLAGS='/MD', LIBS=['kernel32', 'user32', 'runtimeobject'])

Example 2 - Output fragment:

...
scons: warning: vc script errors detected:
[ERROR:vcvars.bat] The UWP Application Platform requires a Windows 10 SDK.
[ERROR:vcvars.bat] WindowsSdkDir = "C:\Program Files (x86)\Windows Kits\8.1\"
[ERROR:vcvars.bat] host/target architecture is not supported : { x64 , x64 }
...
link /nologo /OUT:_build001\hello.exe kernel32.lib user32.lib runtimeobject.lib _build001\hello.obj
LINK : fatal error LNK1104: cannot open file 'MSVCRT.lib'

Important usage details:

• $MSVC_SCRIPTERROR_POLICY must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_SCRIPTERROR_POLICY must be set before the first msvc tool
is loaded into the environment.

• Due to scons implementation details, not all Windows system
environment variables are propagated to the environment in
which the msvc batch file is executed. Depending on Visual
Studio version and installation options, non-fatal msvc batch
file error messages may be generated for ancillary tools which
may not affect builds with the msvc compiler. For this reason,
caution is recommended when setting the script error policy to
raise an exception (e.g., 'Error').

MSVC_SDK_VERSION
Build with a specific version of the Microsoft Software Development
Kit (SDK).

The valid values for $MSVC_SDK_VERSION are: None or a string
containing the requested SDK version (e.g., '10.0.20348.0').

$MSVC_SDK_VERSION is ignored when the value is None and when the
value is an empty string. The validation conditions below do not
apply.

An exception is raised when any of the following conditions are
satisfied:

• $MSVC_SDK_VERSION is specified for Visual Studio 2013 and
earlier.

• $MSVC_SDK_VERSION is specified and an SDK version argument is
specified in $MSVC_SCRIPT_ARGS. Multiple SDK version
declarations via $MSVC_SDK_VERSION and $MSVC_SCRIPT_ARGS are
not allowed.

• The $MSVC_SDK_VERSION specified does not match any of the
supported formats:

• '10.0.XXXXX.Y' [SDK 10.0]

• '8.1' [SDK 8.1]

• The system folder for the corresponding $MSVC_SDK_VERSION
version is not found. The requested SDK version does not appear
to be installed.

• The $MSVC_SDK_VERSION version does not appear to support the
requested platform type (i.e., UWP or Desktop). The requested
SDK version platform type components do not appear to be
installed.

• The $MSVC_SDK_VERSION version is 8.1, the platform type is UWP,
and the build tools selected are from Visual Studio 2017 and
later (i.e., $MSVC_VERSION must be '14.0' or
$MSVC_TOOLSET_VERSION must be '14.0').

Example 1 - A Visual Studio 2022 build with a specific Windows SDK
version:

env = Environment(MSVC_VERSION='14.3', MSVC_SDK_VERSION='10.0.20348.0')

Example 2 - A Visual Studio 2022 build with a specific SDK version
for the Universal Windows Platform:

env = Environment(MSVC_VERSION='14.3', MSVC_SDK_VERSION='10.0.20348.0', MSVC_UWP_APP=True)

Important usage details:

• $MSVC_SDK_VERSION must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_SDK_VERSION must be set before the first msvc tool is
loaded into the environment.

• Should a SDK 10.0 version be installed that does not follow
the naming scheme above, the SDK version will need to be
specified via $MSVC_SCRIPT_ARGS until the version number
validation format can be extended.

• Should an exception be raised indicating that the SDK version
is not found, verify that the requested SDK version is
installed with the necessary platform type components.

• There is a known issue with the Microsoft libraries when the
target architecture is ARM64 and a Windows 11 SDK (version
'10.0.22000.0' and later) is used with the v141 build tools and
older v142 toolsets (versions '14.28.29333' and earlier).
Should build failures arise with these combinations of settings
due to unresolved symbols in the Microsoft libraries,
$MSVC_SDK_VERSION may be employed to specify a Windows 10 SDK
(e.g., '10.0.20348.0') for the build.

MSVC_SPECTRE_LIBS
Build with the spectre-mitigated Visual C++ libraries.

The valid values for $MSVC_SPECTRE_LIBS are: True, False, or None.

When $MSVC_SPECTRE_LIBS is enabled (i.e., True), the Visual C++
environment will include the paths to the spectre-mitigated
implementations of the Microsoft Visual C++ libraries.

An exception is raised when any of the following conditions are
satisfied:

• $MSVC_SPECTRE_LIBS is enabled for Visual Studio 2015 and
earlier.

• $MSVC_SPECTRE_LIBS is enabled and a spectre library argument
is specified in $MSVC_SCRIPT_ARGS. Multiple spectre library
declarations via $MSVC_SPECTRE_LIBS and $MSVC_SCRIPT_ARGS are
not allowed.

• $MSVC_SPECTRE_LIBS is enabled and the platform type is UWP.
There are no spectre-mitigated libraries for Universal Windows
Platform (UWP) applications or components.

Example - A Visual Studio 2022 build with spectre mitigated Visual
C++ libraries:

env = Environment(MSVC_VERSION='14.3', MSVC_SPECTRE_LIBS=True)

Important usage details:

• $MSVC_SPECTRE_LIBS must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_SPECTRE_LIBS must be set before the first msvc tool is
loaded into the environment.

• Additional compiler switches (e.g., /Qspectre) are necessary
for including spectre mitigations when building user artifacts.
Refer to the Visual Studio documentation for details.

•
The existence of the spectre libraries host architecture and
target architecture folders are not verified when
$MSVC_SPECTRE_LIBS is enabled which could result in build
failures. The burden is on the user to ensure the requisite
libraries with spectre mitigations are installed.

MSVC_TOOLSET_VERSION
Build with a specific Visual C++ toolset version.

Specifying $MSVC_TOOLSET_VERSION does not affect the autodetection
and selection of msvc instances. The $MSVC_TOOLSET_VERSION is
applied after an msvc instance is selected. This could be the
default version of msvc if $MSVC_VERSION is not specified.

The valid values for $MSVC_TOOLSET_VERSION are: None or a string
containing the requested toolset version (e.g., '14.29').

$MSVC_TOOLSET_VERSION is ignored when the value is None and when
the value is an empty string. The validation conditions below do
not apply.

An exception is raised when any of the following conditions are
satisfied:

• $MSVC_TOOLSET_VERSION is specified for Visual Studio 2015 and
earlier.

• $MSVC_TOOLSET_VERSION is specified and a toolset version
argument is specified in $MSVC_SCRIPT_ARGS. Multiple toolset
version declarations via $MSVC_TOOLSET_VERSION and
$MSVC_SCRIPT_ARGS are not allowed.

• The $MSVC_TOOLSET_VERSION specified does not match any of the
supported formats:

• 'XX.Y'

• 'XX.YY'

• 'XX.YY.ZZZZZ'

• 'XX.YY.Z' to 'XX.YY.ZZZZ'
[scons extension not directly supported by the msvc batch
files and may be removed in the future]

• 'XX.YY.ZZ.N' [SxS format]

• 'XX.YY.ZZ.NN' [SxS format]

• The major msvc version prefix (i.e., 'XX.Y') of the
$MSVC_TOOLSET_VERSION specified is for Visual Studio 2013 and
earlier (e.g., '12.0').

• The major msvc version prefix (i.e., 'XX.Y') of the
$MSVC_TOOLSET_VERSION specified is greater than the msvc
version selected (e.g., '99.0').

• A system folder for the corresponding $MSVC_TOOLSET_VERSION
version is not found. The requested toolset version does not
appear to be installed.

Toolset selection details:

• When $MSVC_TOOLSET_VERSION is not an SxS version number or a
full toolset version number: the first toolset version, ranked
in descending order, that matches the $MSVC_TOOLSET_VERSION
prefix is selected.

• When $MSVC_TOOLSET_VERSION is specified using the major msvc
version prefix (i.e., 'XX.Y') and the major msvc version is
that of the latest release of Visual Studio, the selected
toolset version may not be the same as the default Visual C++
toolset version.

In the latest release of Visual Studio, the default Visual C++
toolset version is not necessarily the toolset with the largest
version number.

Example 1 - A default Visual Studio build with a partial toolset
version specified:

env = Environment(MSVC_TOOLSET_VERSION='14.2')

Example 2 - A default Visual Studio build with a partial toolset
version specified:

env = Environment(MSVC_TOOLSET_VERSION='14.29')

Example 3 - A Visual Studio 2022 build with a full toolset version
specified:

env = Environment(MSVC_VERSION='14.3', MSVC_TOOLSET_VERSION='14.29.30133')

Example 4 - A Visual Studio 2022 build with an SxS toolset version
specified:

env = Environment(MSVC_VERSION='14.3', MSVC_TOOLSET_VERSION='14.29.16.11')

Important usage details:

• $MSVC_TOOLSET_VERSION must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_TOOLSET_VERSION must be set before the first msvc tool is
loaded into the environment.

•
The existence of the toolset host architecture and target
architecture folders are not verified when
$MSVC_TOOLSET_VERSION is specified which could result in build
failures. The burden is on the user to ensure the requisite
toolset target architecture build tools are installed.

MSVC_USE_SCRIPT
Use a batch script to set up the Microsoft Visual C++ compiler.

If set to the name of a Visual Studio .bat file (e.g. vcvars.bat),
SCons will run that batch file instead of the auto-detected one,
and extract the relevant variables from the result (typically
%INCLUDE%, %LIB%, and %PATH%) for supplying to the build. This can
be useful to force the use of a compiler version that SCons does
not detect. $MSVC_USE_SCRIPT_ARGS provides arguments passed to
this script.

Setting $MSVC_USE_SCRIPT to None bypasses the Visual Studio
autodetection entirely; use this if you are running SCons in a
Visual Studio cmd window and importing the shell's environment
variables - that is, if you are sure everything is set correctly
already and you don't want SCons to change anything.

$MSVC_USE_SCRIPT ignores $MSVC_VERSION and $TARGET_ARCH.

MSVC_USE_SCRIPT_ARGS
Provides arguments passed to the script $MSVC_USE_SCRIPT.

MSVC_USE_SETTINGS
Use a dictionary to set up the Microsoft Visual C++ compiler.

$MSVC_USE_SETTINGS is ignored when $MSVC_USE_SCRIPT is defined
and/or when $MSVC_USE_SETTINGS is set to None.

The dictionary is used to populate the environment with the
relevant variables (typically %INCLUDE%, %LIB%, and %PATH%) for
supplying to the build. This can be useful to force the use of a
compiler environment that SCons does not configure correctly. This
is an alternative to manually configuring the environment when
bypassing Visual Studio autodetection entirely by setting
$MSVC_USE_SCRIPT to None.

Here is an example of configuring a build environment using the
Microsoft Visual C/C++ compiler included in the Microsoft SDK on a
64-bit host and building for a 64-bit architecture:

# Microsoft SDK 6.0 (MSVC 8.0): 64-bit host and 64-bit target
msvc_use_settings = {
"PATH": [
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Bin\\x64",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Bin\\x64",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Bin",
"C:\\Windows\\Microsoft.NET\\Framework\\v2.0.50727",
"C:\\Windows\\system32",
"C:\\Windows",
"C:\\Windows\\System32\\Wbem",
"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\"
],
"INCLUDE": [
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Include",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Include\\Sys",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Include",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Include\\gl",
],
"LIB": [
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Lib\\x64",
"C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Lib\\x64",
],
"LIBPATH": [],
"VSCMD_ARG_app_plat": [],
"VCINSTALLDIR": [],
"VCToolsInstallDir": []
}

# Specifying MSVC_VERSION is recommended
env = Environment(MSVC_VERSION='8.0', MSVC_USE_SETTINGS=msvc_use_settings)

Important usage details:

• $MSVC_USE_SETTINGS must be passed as an argument to the
Environment constructor when an msvc tool (e.g., msvc, msvs,
etc.) is loaded via the default tools list or via a tools list
passed to the Environment constructor. Otherwise,
$MSVC_USE_SETTINGS must be set before the first msvc tool is
loaded into the environment.

•
The dictionary content requirements are based on the internal
msvc implementation and therefore may change at any time. The
burden is on the user to ensure the dictionary contents are
minimally sufficient to ensure successful builds.

MSVC_UWP_APP
Build with the Universal Windows Platform (UWP) application Visual
C++ libraries.

The valid values for $MSVC_UWP_APP are: True, '1', False, '0', or
None.

When $MSVC_UWP_APP is enabled (i.e., True or '1'), the Visual C++
environment will be set up to point to the Windows Store compatible
libraries and Visual C++ runtimes. In doing so, any libraries that
are built will be able to be used in a UWP App and published to the
Windows Store.

An exception is raised when any of the following conditions are
satisfied:

• $MSVC_UWP_APP is enabled for Visual Studio 2013 and earlier.

• $MSVC_UWP_APP is enabled and a UWP argument is specified in
$MSVC_SCRIPT_ARGS. Multiple UWP declarations via $MSVC_UWP_APP
and $MSVC_SCRIPT_ARGS are not allowed.

Example - A Visual Studio 2022 build for the Universal Windows
Platform:

env = Environment(MSVC_VERSION='14.3', MSVC_UWP_APP=True)

Important usage details:

• $MSVC_UWP_APP must be passed as an argument to the Environment
constructor when an msvc tool (e.g., msvc, msvs, etc.) is
loaded via the default tools list or via a tools list passed to
the Environment constructor. Otherwise, $MSVC_UWP_APP must be
set before the first msvc tool is loaded into the environment.

•
The existence of the UWP libraries is not verified when
$MSVC_UWP_APP is enabled which could result in build failures.
The burden is on the user to ensure the requisite UWP libraries
are installed.

MSVC_VERSION
Sets the preferred version of Microsoft Visual C/C++ to use.

If $MSVC_VERSION is not set, SCons will (by default) select the
latest version of Visual C/C++ installed on your system. If the
specified version isn't installed, tool initialization will fail.

$MSVC_VERSION must be passed as an argument to the Environment
constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded
via the default tools list or via a tools list passed to the
Environment constructor. Otherwise, $MSVC_VERSION must be set
before the first msvc tool is loaded into the environment.

Valid values for Windows are 14.3, 14.2, 14.1, 14.1Exp, 14.0,
14.0Exp, 12.0, 12.0Exp, 11.0, 11.0Exp, 10.0, 10.0Exp, 9.0, 9.0Exp,
8.0, 8.0Exp, 7.1, 7.0, and 6.0. Versions ending in Exp refer to
"Express" or "Express for Desktop" editions.

MSVS
When the Microsoft Visual Studio tools are initialized, they set up
this dictionary with the following keys:

VERSION
the version of MSVS being used (can be set via $MSVS_VERSION)

VERSIONS
the available versions of MSVS installed

VCINSTALLDIR
installed directory of Visual C++

VSINSTALLDIR
installed directory of Visual Studio

FRAMEWORKDIR
installed directory of the .NET framework

FRAMEWORKVERSIONS
list of installed versions of the .NET framework, sorted latest
to oldest.

FRAMEWORKVERSION
latest installed version of the .NET framework

FRAMEWORKSDKDIR
installed location of the .NET SDK.

PLATFORMSDKDIR
installed location of the Platform SDK.

PLATFORMSDK_MODULES
dictionary of installed Platform SDK modules, where the
dictionary keys are keywords for the various modules, and the
values are 2-tuples where the first is the release date, and
the second is the version number.

If a value is not set, it was not available in the registry.

MSVS_ARCH
Sets the architecture for which the generated project(s) should
build.

The default value is x86. amd64 is also supported by SCons for
most Visual Studio versions. Since Visual Studio 2015 arm is
supported, and since Visual Studio 2017 arm64 is supported. Trying
to set $MSVS_ARCH to an architecture that's not supported for a
given Visual Studio version will generate an error.

MSVS_PROJECT_GUID
The string placed in a generated Microsoft Visual Studio project
file as the value of the ProjectGUID attribute. There is no default
value. If not defined, a new GUID is generated.

MSVS_SCC_AUX_PATH
The path name placed in a generated Microsoft Visual Studio project
file as the value of the SccAuxPath attribute if the
MSVS_SCC_PROVIDER construction variable is also set. There is no
default value.

MSVS_SCC_CONNECTION_ROOT
The root path of projects in your SCC workspace, i.e the path under
which all project and solution files will be generated. It is used
as a reference path from which the relative paths of the generated
Microsoft Visual Studio project and solution files are computed.
The relative project file path is placed as the value of the
SccLocalPath attribute of the project file and as the values of the
SccProjectFilePathRelativizedFromConnection[i] (where [i] ranges
from 0 to the number of projects in the solution) attributes of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. Similarly the relative solution file path is
placed as the values of the SccLocalPath[i] (where [i] ranges from
0 to the number of projects in the solution) attributes of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. This is used only if the MSVS_SCC_PROVIDER
construction variable is also set. The default value is the current
working directory.

MSVS_SCC_PROJECT_NAME
The project name placed in a generated Microsoft Visual Studio
project file as the value of the SccProjectName attribute if the
MSVS_SCC_PROVIDER construction variable is also set. In this case
the string is also placed in the SccProjectName0 attribute of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. There is no default value.

MSVS_SCC_PROVIDER
The string placed in a generated Microsoft Visual Studio project
file as the value of the SccProvider attribute. The string is also
placed in the SccProvider0 attribute of the
GlobalSection(SourceCodeControl) section of the Microsoft Visual
Studio solution file. There is no default value.

MSVS_VERSION
Sets the preferred version of Microsoft Visual Studio to use.

If $MSVS_VERSION is not set, SCons will (by default) select the
latest version of Visual Studio installed on your system. So, if
you have version 6 and version 7 (MSVS .NET) installed, it will
prefer version 7. You can override this by specifying the
MSVS_VERSION variable in the Environment initialization, setting it
to the appropriate version ('6.0' or '7.0', for example). If the
specified version isn't installed, tool initialization will fail.

This is obsolete: use $MSVC_VERSION instead. If $MSVS_VERSION is
set and $MSVC_VERSION is not, $MSVC_VERSION will be set
automatically to $MSVS_VERSION. If both are set to different
values, scons will raise an error.

MSVSBUILDCOM
The build command line placed in a generated Microsoft Visual
Studio project file. The default is to have Visual Studio invoke
SCons with any specified build targets.

MSVSCLEANCOM
The clean command line placed in a generated Microsoft Visual
Studio project file. The default is to have Visual Studio invoke
SCons with the -c option to remove any specified targets.

MSVSENCODING
The encoding string placed in a generated Microsoft Visual Studio
project file. The default is encoding Windows-1252.

MSVSPROJECTCOM
The action used to generate Microsoft Visual Studio project files.

MSVSPROJECTSUFFIX
The suffix used for Microsoft Visual Studio project (DSP) files.
The default value is .vcproj when using Visual Studio version 7.x
(.NET) or later version, and .dsp when using earlier versions of
Visual Studio.

MSVSREBUILDCOM
The rebuild command line placed in a generated Microsoft Visual
Studio project file. The default is to have Visual Studio invoke
SCons with any specified rebuild targets.

MSVSSCONS
The SCons used in generated Microsoft Visual Studio project files.
The default is the version of SCons being used to generate the
project file.

MSVSSCONSCOM
The default SCons command used in generated Microsoft Visual Studio
project files.

MSVSSCONSCRIPT
The sconscript file (that is, SConstruct or SConscript file) that
will be invoked by Visual Studio project files (through the
$MSVSSCONSCOM variable). The default is the same sconscript file
that contains the call to MSVSProject to build the project file.

MSVSSCONSFLAGS
The SCons flags used in generated Microsoft Visual Studio project
files.

MSVSSOLUTIONCOM
The action used to generate Microsoft Visual Studio solution files.

MSVSSOLUTIONSUFFIX
The suffix used for Microsoft Visual Studio solution (DSW) files.
The default value is .sln when using Visual Studio version 7.x
(.NET), and .dsw when using earlier versions of Visual Studio.

MT
The program used on Windows systems to embed manifests into DLLs
and EXEs. See also $WINDOWS_EMBED_MANIFEST.

MTEXECOM
The Windows command line used to embed manifests into executables.
See also $MTSHLIBCOM.

MTFLAGS
Flags passed to the $MT manifest embedding program (Windows only).

MTSHLIBCOM
The Windows command line used to embed manifests into shared
libraries (DLLs). See also $MTEXECOM.

MWCW_VERSION
The version number of the MetroWerks CodeWarrior C compiler to be
used.

MWCW_VERSIONS
A list of installed versions of the MetroWerks CodeWarrior C
compiler on this system.

NAME
Specfies the name of the project to package.

See the Package builder.

NINJA_ALIAS_NAME
The name of the alias target which will cause SCons to create the
ninja build file, and then (optionally) run ninja. The default
value is generate-ninja.

NINJA_CMD_ARGS
A string which will pass arguments through SCons to the ninja
command when scons executes ninja. Has no effect if
$NINJA_DISABLE_AUTO_RUN is set.

This value can also be passed on the command line:

scons NINJA_CMD_ARGS=-v
or
scons NINJA_CMD_ARGS="-v -j 3"

NINJA_COMPDB_EXPAND
Boolean value to instruct ninja to expand the command line
arguments normally put into response files. If true, prevents
unexpanded lines in the compilation database like “gcc @rsp_file”
and instead yields expanded lines like “gcc -c -o myfile.o myfile.c
-Ia -DXYZ”.

Ninja's compdb tool added the -x flag in Ninja V1.9.0

NINJA_DEPFILE_PARSE_FORMAT
Determines the type of format ninja should expect when parsing
header include depfiles. Can be msvc, gcc, or clang. The msvc
option corresponds to /showIncludes format, and gcc or clang
correspond to -MMD -MF.

NINJA_DIR
The builddir value. Propagates directly into the generated ninja
build file. From Ninja's docs: “ A directory for some Ninja output
files. ... (You can also store other build output in this
directory.) ” The default value is .ninja.

NINJA_DISABLE_AUTO_RUN
Boolean. Default: False. If true, SCons will not run ninja
automatically after creating the ninja build file.

If not explicitly set, this will be set to True if
--disable_execute_ninja or SetOption('disable_execute_ninja', True)
is seen.

NINJA_ENV_VAR_CACHE
A string that sets the environment for any environment variables
that differ between the OS environment and the SCons execution
environment.

It will be compatible with the default shell of the operating
system.

If not explicitly set, SCons will generate this dynamically from
the execution environment stored in the current construction
environment (e.g. env['ENV']) where those values differ from the
existing shell..

NINJA_FILE_NAME
The filename for the generated Ninja build file. The default is
ninja.build.

NINJA_FORCE_SCONS_BUILD
If true, causes the build nodes to callback to scons instead of
using ninja to build them. This is intended to be passed to the
environment on the builder invocation. It is useful if you have a
build node which does something which is not easily translated into
ninja.

NINJA_GENERATED_SOURCE_ALIAS_NAME
A string matching the name of a user defined alias which represents
a list of all generated sources. This will prevent the
auto-detection of generated sources from
$NINJA_GENERATED_SOURCE_SUFFIXES. Then all other source files will
be made to depend on this in the ninja build file, forcing the
generated sources to be built first.

NINJA_GENERATED_SOURCE_SUFFIXES
The list of source file suffixes which are generated by SCons build
steps. All source files which match these suffixes will be added to
the _generated_sources alias in the output ninja build file. Then
all other source files will be made to depend on this in the ninja
build file, forcing the generated sources to be built first.

NINJA_MSVC_DEPS_PREFIX
The msvc_deps_prefix string. Propagates directly into the generated
ninja build file. From Ninja's docs: “defines the string which
should be stripped from msvc's /showIncludes output”

NINJA_POOL
Set the ninja_pool for this or all targets in scope for this env
var.

NINJA_REGENERATE_DEPS
A generator function used to create a ninja depfile which includes
all the files which would require SCons to be invoked if they
change. Or a list of said files.

_NINJA_REGENERATE_DEPS_FUNC
Internal value used to specify the function to call with argument
env to generate the list of files which if changed would require
the ninja build file to be regenerated.

NINJA_SCONS_DAEMON_KEEP_ALIVE
The number of seconds for the SCons deamon launched by ninja to
stay alive. (Default: 180000)

NINJA_SCONS_DAEMON_PORT
The TCP/IP port for the SCons daemon to listen on. NOTE: You
cannot use a port already being listened to on your build machine.
(Default: random number between 10000,60000)

NINJA_SYNTAX
The path to a custom ninja_syntax.py file which is used in
generation. The tool currently assumes you have ninja installed as
a Python module and grabs the syntax file from that installation if
$NINJA_SYNTAX is not explicitly set.

no_import_lib
When set to non-zero, suppresses creation of a corresponding
Windows static import lib by the SharedLibrary builder when used
with MinGW, Microsoft Visual Studio or Metrowerks. This also
suppresses creation of an export (.exp) file when using Microsoft
Visual Studio.

OBJPREFIX
The prefix used for (static) object file names.

OBJSUFFIX
The suffix used for (static) object file names.

PACKAGEROOT
Specifies the directory where all files in resulting archive will
be placed if applicable. The default value is “$NAME-$VERSION”.

See the Package builder.

PACKAGETYPE
Selects the package type to build when using the Package builder.
May be a string or list of strings. See the docuentation for the
builder for the currently supported types.

$PACKAGETYPE may be overridden with the --package-type command line
option.

See the Package builder.

PACKAGEVERSION
The version of the package (not the underlying project). This is
currently only used by the rpm packager and should reflect changes
in the packaging, not the underlying project code itself.

See the Package builder.

PCH
The Microsoft Visual C++ precompiled header that will be used when
compiling object files. This variable is ignored by tools other
than Microsoft Visual C++. When this variable is defined SCons will
add options to the compiler command line to cause it to use the
precompiled header, and will also set up the dependencies for the
PCH file. Example:

env['PCH'] = File('StdAfx.pch')

PCHCOM
The command line used by the PCH builder to generated a precompiled
header.

PCHCOMSTR
The string displayed when generating a precompiled header. If this
is not set, then $PCHCOM (the command line) is displayed.

PCHPDBFLAGS
A construction variable that, when expanded, adds the /yD flag to
the command line only if the $PDB construction variable is set.

PCHSTOP
This variable specifies how much of a source file is precompiled.
This variable is ignored by tools other than Microsoft Visual C++,
or when the PCH variable is not being used. When this variable is
define it must be a string that is the name of the header that is
included at the end of the precompiled portion of the source files,
or the empty string if the "#pragma hrdstop" construct is being
used:

env['PCHSTOP'] = 'StdAfx.h'

PDB
The Microsoft Visual C++ PDB file that will store debugging
information for object files, shared libraries, and programs. This
variable is ignored by tools other than Microsoft Visual C++. When
this variable is defined SCons will add options to the compiler and
linker command line to cause them to generate external debugging
information, and will also set up the dependencies for the PDB
file. Example:

env['PDB'] = 'hello.pdb'

The Visual C++ compiler switch that SCons uses by default to
generate PDB information is /Z7. This works correctly with parallel
(-j) builds because it embeds the debug information in the
intermediate object files, as opposed to sharing a single PDB file
between multiple object files. This is also the only way to get
debug information embedded into a static library. Using the /Zi
instead may yield improved link-time performance, although parallel
builds will no longer work. You can generate PDB files with the /Zi
switch by overriding the default $CCPDBFLAGS variable; see the
entry for that variable for specific examples.

PDFLATEX
The pdflatex utility.

PDFLATEXCOM
The command line used to call the pdflatex utility.

PDFLATEXCOMSTR
The string displayed when calling the pdflatex utility. If this is
not set, then $PDFLATEXCOM (the command line) is displayed.

env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")

PDFLATEXFLAGS
General options passed to the pdflatex utility.

PDFPREFIX
The prefix used for PDF file names.

PDFSUFFIX
The suffix used for PDF file names.

PDFTEX
The pdftex utility.

PDFTEXCOM
The command line used to call the pdftex utility.

PDFTEXCOMSTR
The string displayed when calling the pdftex utility. If this is
not set, then $PDFTEXCOM (the command line) is displayed.

env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

PDFTEXFLAGS
General options passed to the pdftex utility.

PKGCHK
On Solaris systems, the package-checking program that will be used
(along with $PKGINFO) to look for installed versions of the Sun PRO
C++ compiler. The default is /usr/sbin/pgkchk.

PKGINFO
On Solaris systems, the package information program that will be
used (along with $PKGCHK) to look for installed versions of the Sun
PRO C++ compiler. The default is pkginfo.

PLATFORM
The name of the platform used to create this construction
environment. SCons sets this when initializing the platform, which
by default is auto-detected (see the platform argument to
Environment).

env = Environment(tools=[])
if env['PLATFORM'] == 'cygwin':
Tool('mingw')(env)
else:
Tool('msvc')(env)

POAUTOINIT
The $POAUTOINIT variable, if set to True (on non-zero numeric
value), let the msginit tool to automatically initialize missing PO
files with msginit(1). This applies to both, POInit and POUpdate
builders (and others that use any of them).

POCREATE_ALIAS
Common alias for all PO files created with POInit builder (default:
'po-create'). See msginit tool and POInit builder.

POSUFFIX
Suffix used for PO files (default: '.po') See msginit tool and
POInit builder.

POTDOMAIN
The $POTDOMAIN defines default domain, used to generate POT
filename as $POTDOMAIN.pot when no POT file name is provided by the
user. This applies to POTUpdate, POInit and POUpdate builders (and
builders, that use them, e.g. Translate). Normally (if $POTDOMAIN
is not defined), the builders use messages.pot as default POT file
name.

POTSUFFIX
Suffix used for PO Template files (default: '.pot'). See xgettext
tool and POTUpdate builder.

POTUPDATE_ALIAS
Name of the common phony target for all PO Templates created with
POUpdate (default: 'pot-update'). See xgettext tool and POTUpdate
builder.

POUPDATE_ALIAS
Common alias for all PO files being defined with POUpdate builder
(default: 'po-update'). See msgmerge tool and POUpdate builder.

PRINT_CMD_LINE_FUNC
A Python function used to print the command lines as they are
executed (assuming command printing is not disabled by the -q or -s
options or their equivalents). The function must accept four
arguments: s, target, source and env. s is a string showing the
command being executed, target, is the target being built (file
node, list, or string name(s)), source, is the source(s) used (file
node, list, or string name(s)), and env is the environment being
used.

The function must do the printing itself. The default
implementation, used if this variable is not set or is None, is to
just print the string, as in:

def print_cmd_line(s, target, source, env):
sys.stdout.write(s + "\n")

Here is an example of a more interesting function:

def print_cmd_line(s, target, source, env):
sys.stdout.write(
"Building %s -> %s...\n"
% (
' and '.join([str(x) for x in source]),
' and '.join([str(x) for x in target]),
)
)

env = Environment(PRINT_CMD_LINE_FUNC=print_cmd_line)
env.Program('foo', ['foo.c', 'bar.c'])

This prints:

...
scons: Building targets ...
Building bar.c -> bar.o...
Building foo.c -> foo.o...
Building foo.o and bar.o -> foo...
scons: done building targets.

Another example could be a function that logs the actual commands
to a file.

PROGEMITTER
Contains the emitter specification for the Program builder. The
manpage section "Builder Objects" contains general information on
specifying emitters.

PROGPREFIX
The prefix used for executable file names.

PROGSUFFIX
The suffix used for executable file names.

PSCOM
The command line used to convert TeX DVI files into a PostScript
file.

PSCOMSTR
The string displayed when a TeX DVI file is converted into a
PostScript file. If this is not set, then $PSCOM (the command line)
is displayed.

PSPREFIX
The prefix used for PostScript file names.

PSSUFFIX
The prefix used for PostScript file names.

QT_AUTOSCAN
Turn off scanning for mocable files. Use the Moc Builder to
explicitly specify files to run moc on.

QT_BINPATH
The path where the Qt binaries are installed. The default value is
'$QTDIR/bin'.

QT_CPPPATH
The path where the Qt header files are installed. The default value
is '$QTDIR/include'. Note: If you set this variable to None, the
tool won't change the $CPPPATH construction variable.

QT_DEBUG
Prints lots of debugging information while scanning for moc files.

QT_LIB
Default value is 'qt'. You may want to set this to 'qt-mt'. Note:
If you set this variable to None, the tool won't change the $LIBS
variable.

QT_LIBPATH
The path where the Qt libraries are installed. The default value is
'$QTDIR/lib'. Note: If you set this variable to None, the tool
won't change the $LIBPATH construction variable.

QT_MOC
Default value is '$QT_BINPATH/moc'.

QT_MOCCXXPREFIX
Default value is ''. Prefix for moc output files when source is a
C++ file.

QT_MOCCXXSUFFIX
Default value is '.moc'. Suffix for moc output files when source is
a C++ file.

QT_MOCFROMCXXCOM
Command to generate a moc file from a C++ file.

QT_MOCFROMCXXCOMSTR
The string displayed when generating a moc file from a C++ file. If
this is not set, then $QT_MOCFROMCXXCOM (the command line) is
displayed.

QT_MOCFROMCXXFLAGS
Default value is '-i'. These flags are passed to moc when moccing a
C++ file.

QT_MOCFROMHCOM
Command to generate a moc file from a header.

QT_MOCFROMHCOMSTR
The string displayed when generating a moc file from a C++ file. If
this is not set, then $QT_MOCFROMHCOM (the command line) is
displayed.

QT_MOCFROMHFLAGS
Default value is ''. These flags are passed to moc when moccing a
header file.

QT_MOCHPREFIX
Default value is 'moc_'. Prefix for moc output files when source is
a header.

QT_MOCHSUFFIX
Default value is '$CXXFILESUFFIX'. Suffix for moc output files when
source is a header.

QT_UIC
Default value is '$QT_BINPATH/uic'.

QT_UICCOM
Command to generate header files from .ui files.

QT_UICCOMSTR
The string displayed when generating header files from .ui files.
If this is not set, then $QT_UICCOM (the command line) is
displayed.

QT_UICDECLFLAGS
Default value is ''. These flags are passed to uic when creating a
header file from a .ui file.

QT_UICDECLPREFIX
Default value is ''. Prefix for uic generated header files.

QT_UICDECLSUFFIX
Default value is '.h'. Suffix for uic generated header files.

QT_UICIMPLFLAGS
Default value is ''. These flags are passed to uic when creating a
C++ file from a .ui file.

QT_UICIMPLPREFIX
Default value is 'uic_'. Prefix for uic generated implementation
files.

QT_UICIMPLSUFFIX
Default value is '$CXXFILESUFFIX'. Suffix for uic generated
implementation files.

QT_UISUFFIX
Default value is '.ui'. Suffix of designer input files.

QTDIR
The path to the Qt installation to build against. If not already
set, qt tool tries to obtain this from os.environ; if not found
there, it tries to make a guess.

RANLIB
The archive indexer.

RANLIBCOM
The command line used to index a static library archive.

RANLIBCOMSTR
The string displayed when a static library archive is indexed. If
this is not set, then $RANLIBCOM (the command line) is displayed.

env = Environment(RANLIBCOMSTR = "Indexing $TARGET")

RANLIBFLAGS
General options passed to the archive indexer.

RC
The resource compiler used to build a Microsoft Visual C++ resource
file.

RCCOM
The command line used to build a Microsoft Visual C++ resource
file.

RCCOMSTR
The string displayed when invoking the resource compiler to build a
Microsoft Visual C++ resource file. If this is not set, then $RCCOM
(the command line) is displayed.

RCFLAGS
The flags passed to the resource compiler by the RES builder.

RCINCFLAGS
An automatically-generated construction variable containing the
command-line options for specifying directories to be searched by
the resource compiler. The value of $RCINCFLAGS is created by
respectively prepending and appending $RCINCPREFIX and $RCINCSUFFIX
to the beginning and end of each directory in $CPPPATH.

RCINCPREFIX
The prefix (flag) used to specify an include directory on the
resource compiler command line. This will be prepended to the
beginning of each directory in the $CPPPATH construction variable
when the $RCINCFLAGS variable is expanded.

RCINCSUFFIX
The suffix used to specify an include directory on the resource
compiler command line. This will be appended to the end of each
directory in the $CPPPATH construction variable when the
$RCINCFLAGS variable is expanded.

RDirs
A function that converts a string into a list of Dir instances by
searching the repositories.

REGSVR
The program used on Windows systems to register a newly-built DLL
library whenever the SharedLibrary builder is passed a keyword
argument of register=True.

REGSVRCOM
The command line used on Windows systems to register a newly-built
DLL library whenever the SharedLibrary builder is passed a keyword
argument of register=True.

REGSVRCOMSTR
The string displayed when registering a newly-built DLL file. If
this is not set, then $REGSVRCOM (the command line) is displayed.

REGSVRFLAGS
Flags passed to the DLL registration program on Windows systems
when a newly-built DLL library is registered. By default, this
includes the /s that prevents dialog boxes from popping up and
requiring user attention.

RMIC
The Java RMI stub compiler.

RMICCOM
The command line used to compile stub and skeleton class files from
Java classes that contain RMI implementations. Any options
specified in the $RMICFLAGS construction variable are included on
this command line.

RMICCOMSTR
The string displayed when compiling stub and skeleton class files
from Java classes that contain RMI implementations. If this is not
set, then $RMICCOM (the command line) is displayed.

env = Environment(RMICCOMSTR = "Generating stub/skeleton class files $TARGETS from $SOURCES")

RMICFLAGS
General options passed to the Java RMI stub compiler.

RPATH
A list of paths to search for shared libraries when running
programs. Currently only used in the GNU (gnulink), IRIX (sgilink)
and Sun (sunlink) linkers. Ignored on platforms and toolchains that
don't support it. Note that the paths added to RPATH are not
transformed by scons in any way: if you want an absolute path, you
must make it absolute yourself.

_RPATH
An automatically-generated construction variable containing the
rpath flags to be used when linking a program with shared
libraries. The value of $_RPATH is created by respectively
prepending $RPATHPREFIX and appending $RPATHSUFFIX to the beginning
and end of each directory in $RPATH.

RPATHPREFIX
The prefix used to specify a directory to be searched for shared
libraries when running programs. This will be prepended to the
beginning of each directory in the $RPATH construction variable
when the $_RPATH variable is automatically generated.

RPATHSUFFIX
The suffix used to specify a directory to be searched for shared
libraries when running programs. This will be appended to the end
of each directory in the $RPATH construction variable when the
$_RPATH variable is automatically generated.

RPCGEN
The RPC protocol compiler.

RPCGENCLIENTFLAGS
Options passed to the RPC protocol compiler when generating client
side stubs. These are in addition to any flags specified in the
$RPCGENFLAGS construction variable.

RPCGENFLAGS
General options passed to the RPC protocol compiler.

RPCGENHEADERFLAGS
Options passed to the RPC protocol compiler when generating a
header file. These are in addition to any flags specified in the
$RPCGENFLAGS construction variable.

RPCGENSERVICEFLAGS
Options passed to the RPC protocol compiler when generating server
side stubs. These are in addition to any flags specified in the
$RPCGENFLAGS construction variable.

RPCGENXDRFLAGS
Options passed to the RPC protocol compiler when generating XDR
routines. These are in addition to any flags specified in the
$RPCGENFLAGS construction variable.

SCANNERS
A list of the available implicit dependency scanners. New file
scanners may be added by appending to this list, although the more
flexible approach is to associate scanners with a specific Builder.
See the manpage sections "Builder Objects" and "Scanner Objects"
for more information.

SCONS_HOME
The (optional) path to the SCons library directory, initialized
from the external environment. If set, this is used to construct a
shorter and more efficient search path in the $MSVSSCONS command
line executed from Microsoft Visual Studio project files.

SHCC
The C compiler used for generating shared-library objects. See also
$CC for compiling to static objects.

SHCCCOM
The command line used to compile a C source file to a
shared-library object file. Any options specified in the $SHCFLAGS,
$SHCCFLAGS and $CPPFLAGS construction variables are included on
this command line. See also $CCCOM for compiling to static objects.

SHCCCOMSTR
If set, the string displayed when a C source file is compiled to a
shared object file. If not set, then $SHCCCOM (the command line) is
displayed. See also $CCCOMSTR for compiling to static objects.

env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")

SHCCFLAGS
Options that are passed to the C and C++ compilers to generate
shared-library objects. See also $CCFLAGS for compiling to static
objects.

SHCFLAGS
Options that are passed to the C compiler (only; not C++) to
generate shared-library objects. See also $CFLAGS for compiling to
static objects.

SHCXX
The C++ compiler used for generating shared-library objects. See
also $CXX for compiling to static objects.

SHCXXCOM
The command line used to compile a C++ source file to a
shared-library object file. Any options specified in the
$SHCXXFLAGS and $CPPFLAGS construction variables are included on
this command line. See also $CXXCOM for compiling to static
objects.

SHCXXCOMSTR
If set, the string displayed when a C++ source file is compiled to
a shared object file. If not set, then $SHCXXCOM (the command line)
is displayed. See also $CXXCOMSTR for compiling to static objects.

env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")

SHCXXFLAGS
Options that are passed to the C++ compiler to generate
shared-library objects. See also $CXXFLAGS for compiling to static
objects.

SHDC
The name of the compiler to use when compiling D source destined to
be in a shared objects. See also $DC for compiling to static
objects.

SHDCOM
The command line to use when compiling code to be part of shared
objects. See also $DCOM for compiling to static objects.

SHDCOMSTR
If set, the string displayed when a D source file is compiled to a
(shared) object file. If not set, then $SHDCOM (the command line)
is displayed. See also $DCOMSTR for compiling to static objects.

SHDLIBVERSIONFLAGS
Extra flags added to $SHDLINKCOM when building versioned
SharedLibrary. These flags are only used when $SHLIBVERSION is set.

SHDLINK
The linker to use when creating shared objects for code bases
include D sources. See also $DLINK for linking static objects.

SHDLINKCOM
The command line to use when generating shared objects. See also
$DLINKCOM for linking static objects.

SHDLINKFLAGS
The list of flags to use when generating a shared object. See also
$DLINKFLAGS for linking static objects.

SHELL
A string naming the shell program that will be passed to the $SPAWN
function. See the $SPAWN construction variable for more
information.

SHELL_ENV_GENERATORS
Must be a list (or an iterable) containing functions where each
function generates or alters the environment dictionary which will
be used when executing the $SPAWN function. The functions will
initially be passed a reference of the current execution
environment (e.g. env['ENV']), and each called while iterating the
list. Each function must return a dictionary which will then be
passed to the next function iterated. The return dictionary should
contain keys which represent the environment variables and their
respective values. This primary purpose of this construction
variable is to give the user the ability to substitute execution
environment variables based on env, targets, and sources. If
desired, the user can completely customize the execution
environment for particular targets.

def custom_shell_env(env, target, source, shell_env):
"""customize shell_env if desired"""
if str(target[0]) == 'special_target':
shell_env['SPECIAL_VAR'] = env.subst('SOME_VAR', target=target, source=source)
return shell_env

env["SHELL_ENV_GENERATORS"] = [custom_shell_env]

env The SCons construction environment from which the execution
environment can be derived from.

target The list of targets associated with this action.

source The list of sources associated with this action.

shell_env The current shell_env after iterating other
SHELL_ENV_GENERATORS functions. This can be compared to the passed
env['ENV'] to detect any changes.

SHF03
The Fortran 03 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN variable, which specifies
the default Fortran compiler for all Fortran versions. You only
need to set $SHF03 if you need to use a specific compiler or
compiler version for Fortran 03 files.

SHF03COM
The command line used to compile a Fortran 03 source file to a
shared-library object file. You only need to set $SHF03COM if you
need to use a specific command line for Fortran 03 files. You
should normally set the $SHFORTRANCOM variable, which specifies the
default command line for all Fortran versions.

SHF03COMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to a shared-library object file. If not set, then
$SHF03COM or $SHFORTRANCOM (the command line) is displayed.

SHF03FLAGS
Options that are passed to the Fortran 03 compiler to generated
shared-library objects. You only need to set $SHF03FLAGS if you
need to define specific user options for Fortran 03 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default Fortran
compiler for all Fortran versions.

SHF03PPCOM
The command line used to compile a Fortran 03 source file to a
shared-library object file after first running the file through the
C preprocessor. Any options specified in the $SHF03FLAGS and
$CPPFLAGS construction variables are included on this command line.
You only need to set $SHF03PPCOM if you need to use a specific
C-preprocessor command line for Fortran 03 files. You should
normally set the $SHFORTRANPPCOM variable, which specifies the
default C-preprocessor command line for all Fortran versions.

SHF03PPCOMSTR
If set, the string displayed when a Fortran 03 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF03PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF08
The Fortran 08 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN variable, which specifies
the default Fortran compiler for all Fortran versions. You only
need to set $SHF08 if you need to use a specific compiler or
compiler version for Fortran 08 files.

SHF08COM
The command line used to compile a Fortran 08 source file to a
shared-library object file. You only need to set $SHF08COM if you
need to use a specific command line for Fortran 08 files. You
should normally set the $SHFORTRANCOM variable, which specifies the
default command line for all Fortran versions.

SHF08COMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to a shared-library object file. If not set, then
$SHF08COM or $SHFORTRANCOM (the command line) is displayed.

SHF08FLAGS
Options that are passed to the Fortran 08 compiler to generated
shared-library objects. You only need to set $SHF08FLAGS if you
need to define specific user options for Fortran 08 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default Fortran
compiler for all Fortran versions.

SHF08PPCOM
The command line used to compile a Fortran 08 source file to a
shared-library object file after first running the file through the
C preprocessor. Any options specified in the $SHF08FLAGS and
$CPPFLAGS construction variables are included on this command line.
You only need to set $SHF08PPCOM if you need to use a specific
C-preprocessor command line for Fortran 08 files. You should
normally set the $SHFORTRANPPCOM variable, which specifies the
default C-preprocessor command line for all Fortran versions.

SHF08PPCOMSTR
If set, the string displayed when a Fortran 08 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF08PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF77
The Fortran 77 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN variable, which specifies
the default Fortran compiler for all Fortran versions. You only
need to set $SHF77 if you need to use a specific compiler or
compiler version for Fortran 77 files.

SHF77COM
The command line used to compile a Fortran 77 source file to a
shared-library object file. You only need to set $SHF77COM if you
need to use a specific command line for Fortran 77 files. You
should normally set the $SHFORTRANCOM variable, which specifies the
default command line for all Fortran versions.

SHF77COMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to a shared-library object file. If not set, then
$SHF77COM or $SHFORTRANCOM (the command line) is displayed.

SHF77FLAGS
Options that are passed to the Fortran 77 compiler to generated
shared-library objects. You only need to set $SHF77FLAGS if you
need to define specific user options for Fortran 77 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default Fortran
compiler for all Fortran versions.

SHF77PPCOM
The command line used to compile a Fortran 77 source file to a
shared-library object file after first running the file through the
C preprocessor. Any options specified in the $SHF77FLAGS and
$CPPFLAGS construction variables are included on this command line.
You only need to set $SHF77PPCOM if you need to use a specific
C-preprocessor command line for Fortran 77 files. You should
normally set the $SHFORTRANPPCOM variable, which specifies the
default C-preprocessor command line for all Fortran versions.

SHF77PPCOMSTR
If set, the string displayed when a Fortran 77 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF77PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF90
The Fortran 90 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN variable, which specifies
the default Fortran compiler for all Fortran versions. You only
need to set $SHF90 if you need to use a specific compiler or
compiler version for Fortran 90 files.

SHF90COM
The command line used to compile a Fortran 90 source file to a
shared-library object file. You only need to set $SHF90COM if you
need to use a specific command line for Fortran 90 files. You
should normally set the $SHFORTRANCOM variable, which specifies the
default command line for all Fortran versions.

SHF90COMSTR
If set, the string displayed when a Fortran 90 source file is
compiled to a shared-library object file. If not set, then
$SHF90COM or $SHFORTRANCOM (the command line) is displayed.

SHF90FLAGS
Options that are passed to the Fortran 90 compiler to generated
shared-library objects. You only need to set $SHF90FLAGS if you
need to define specific user options for Fortran 90 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default Fortran
compiler for all Fortran versions.

SHF90PPCOM
The command line used to compile a Fortran 90 source file to a
shared-library object file after first running the file through the
C preprocessor. Any options specified in the $SHF90FLAGS and
$CPPFLAGS construction variables are included on this command line.
You only need to set $SHF90PPCOM if you need to use a specific
C-preprocessor command line for Fortran 90 files. You should
normally set the $SHFORTRANPPCOM variable, which specifies the
default C-preprocessor command line for all Fortran versions.

SHF90PPCOMSTR
If set, the string displayed when a Fortran 90 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF90PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHF95
The Fortran 95 compiler used for generating shared-library objects.
You should normally set the $SHFORTRAN variable, which specifies
the default Fortran compiler for all Fortran versions. You only
need to set $SHF95 if you need to use a specific compiler or
compiler version for Fortran 95 files.

SHF95COM
The command line used to compile a Fortran 95 source file to a
shared-library object file. You only need to set $SHF95COM if you
need to use a specific command line for Fortran 95 files. You
should normally set the $SHFORTRANCOM variable, which specifies the
default command line for all Fortran versions.

SHF95COMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to a shared-library object file. If not set, then
$SHF95COM or $SHFORTRANCOM (the command line) is displayed.

SHF95FLAGS
Options that are passed to the Fortran 95 compiler to generated
shared-library objects. You only need to set $SHF95FLAGS if you
need to define specific user options for Fortran 95 files. You
should normally set the $FORTRANCOMMONFLAGS variable, which
specifies the user-specified options passed to the default Fortran
compiler for all Fortran versions.

SHF95PPCOM
The command line used to compile a Fortran 95 source file to a
shared-library object file after first running the file through the
C preprocessor. Any options specified in the $SHF95FLAGS and
$CPPFLAGS construction variables are included on this command line.
You only need to set $SHF95PPCOM if you need to use a specific
C-preprocessor command line for Fortran 95 files. You should
normally set the $SHFORTRANPPCOM variable, which specifies the
default C-preprocessor command line for all Fortran versions.

SHF95PPCOMSTR
If set, the string displayed when a Fortran 95 source file is
compiled to a shared-library object file after first running the
file through the C preprocessor. If not set, then $SHF95PPCOM or
$SHFORTRANPPCOM (the command line) is displayed.

SHFORTRAN
The default Fortran compiler used for generating shared-library
objects.

SHFORTRANCOM
The command line used to compile a Fortran source file to a
shared-library object file. By default, any options specified in
the $SHFORTRANFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS
construction variables are included on this command line. See also
$FORTRANCOM.

SHFORTRANCOMSTR
If set, the string displayed when a Fortran source file is compiled
to a shared-library object file. If not set, then $SHFORTRANCOM
(the command line) is displayed.

SHFORTRANFLAGS
Options that are passed to the Fortran compiler to generate
shared-library objects.

SHFORTRANPPCOM
The command line used to compile a Fortran source file to a
shared-library object file after first running the file through the
C preprocessor. By default, any options specified in the
$SHFORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and
$_FORTRANINCFLAGS construction variables are included on this
command line. See also $SHFORTRANCOM.

SHFORTRANPPCOMSTR
If set, the string displayed when a Fortran source file is compiled
to a shared-library object file after first running the file
through the C preprocessor. If not set, then $SHFORTRANPPCOM (the
command line) is displayed.

SHLIBEMITTER
Contains the emitter specification for the SharedLibrary builder.
The manpage section "Builder Objects" contains general information
on specifying emitters.

SHLIBNOVERSIONSYMLINKS
Instructs the SharedLibrary builder to not create symlinks for
versioned shared libraries.

SHLIBPREFIX
The prefix used for shared library file names.

_SHLIBSONAME
A macro that automatically generates shared library's SONAME based
on $TARGET, $SHLIBVERSION and $SHLIBSUFFIX. Used by SharedLibrary
builder when the linker tool supports SONAME (e.g. gnulink).

SHLIBSUFFIX
The suffix used for shared library file names.

SHLIBVERSION
When this construction variable is defined, a versioned shared
library is created by the SharedLibrary builder. This activates the
$_SHLIBVERSIONFLAGS and thus modifies the $SHLINKCOM as required,
adds the version number to the library name, and creates the
symlinks that are needed. $SHLIBVERSION versions should exist as
alpha-numeric, decimal-delimited values as defined by the regular
expression "\w+[\.\w+]*". Example $SHLIBVERSION values include '1',
'1.2.3', and '1.2.gitaa412c8b'.

_SHLIBVERSIONFLAGS
This macro automatically introduces extra flags to $SHLINKCOM when
building versioned SharedLibrary (that is when $SHLIBVERSION is
set). _SHLIBVERSIONFLAGS usually adds $SHLIBVERSIONFLAGS and some
extra dynamically generated options (such as
-Wl,-soname=$_SHLIBSONAME. It is unused by "plain" (unversioned)
shared libraries.

SHLIBVERSIONFLAGS
Extra flags added to $SHLINKCOM when building versioned
SharedLibrary. These flags are only used when $SHLIBVERSION is set.

SHLINK
The linker for programs that use shared libraries. See also $LINK
for linking static objects.

On POSIX systems (those using the link tool), you should normally
not change this value as it defaults to a "smart" linker tool which
selects a compiler driver matching the type of source files in use.
So for example, if you set $SHCXX to a specific compiler name, and
are compiling C++ sources, the smartlink function will
automatically select the same compiler for linking.

SHLINKCOM
The command line used to link programs using shared libraries. See
also $LINKCOM for linking static objects.

SHLINKCOMSTR
The string displayed when programs using shared libraries are
linked. If this is not set, then $SHLINKCOM (the command line) is
displayed. See also $LINKCOMSTR for linking static objects.

env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")

SHLINKFLAGS
General user options passed to the linker for programs using shared
libraries. Note that this variable should not contain -l (or
similar) options for linking with the libraries listed in $LIBS,
nor -L (or similar) include search path options that scons
generates automatically from $LIBPATH. See $_LIBFLAGS above, for
the variable that expands to library-link options, and
$_LIBDIRFLAGS above, for the variable that expands to library
search path options. See also $LINKFLAGS for linking static
objects.

SHOBJPREFIX
The prefix used for shared object file names.

SHOBJSUFFIX
The suffix used for shared object file names.

SONAME
Variable used to hard-code SONAME for versioned shared
library/loadable module.

env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SONAME='libtest.so.2')

The variable is used, for example, by gnulink linker tool.

SOURCE
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

SOURCE_URL
The URL (web address) of the location from which the project was
retrieved. This is used to fill in the Source: field in the
controlling information for Ipkg and RPM packages.

See the Package builder.

SOURCES
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

SOVERSION
This will construct the SONAME using on the base library name (test
in the example below) and use specified SOVERSION to create SONAME.

env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SOVERSION='2')

The variable is used, for example, by gnulink linker tool.

In the example above SONAME would be libtest.so.2 which would be a
symlink and point to libtest.so.0.1.2

SPAWN
A command interpreter function that will be called to execute
command line strings. The function must accept five arguments:

def spawn(shell, escape, cmd, args, env):

shell is a string naming the shell program to use, escape is a
function that can be called to escape shell special characters in
the command line, cmd is the path to the command to be executed,
args holds the arguments to the command and env is a dictionary of
environment variables defining the execution environment in which
the command should be executed.

STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME
When this variable is true, static objects and shared objects are
assumed to be the same; that is, SCons does not check for linking
static objects into a shared library.

SUBST_DICT
The dictionary used by the Substfile or Textfile builders for
substitution values. It can be anything acceptable to the dict()
constructor, so in addition to a dictionary, lists of tuples are
also acceptable.

SUBSTFILEPREFIX
The prefix used for Substfile file names, an empty string by
default.

SUBSTFILESUFFIX
The suffix used for Substfile file names, an empty string by
default.

SUMMARY
A short summary of what the project is about. This is used to fill
in the Summary: field in the controlling information for Ipkg and
RPM packages, and as the Description: field in MSI packages.

See the Package builder.

SWIG
The name of the SWIG compiler to use.

SWIGCFILESUFFIX
The suffix that will be used for intermediate C source files
generated by SWIG. The default value is '_wrap$CFILESUFFIX' - that
is, the concatenation of the string _wrap and the current C suffix
$CFILESUFFIX. By default, this value is used whenever the -c++
option is not specified as part of the $SWIGFLAGS construction
variable.

SWIGCOM
The command line used to call SWIG.

SWIGCOMSTR
The string displayed when calling SWIG. If this is not set, then
$SWIGCOM (the command line) is displayed.

SWIGCXXFILESUFFIX
The suffix that will be used for intermediate C++ source files
generated by SWIG. The default value is '_wrap$CXXFILESUFFIX' -
that is, the concatenation of the string _wrap and the current C++
suffix $CXXFILESUFFIX. By default, this value is used whenever the
-c++ option is specified as part of the $SWIGFLAGS construction
variable.

SWIGDIRECTORSUFFIX
The suffix that will be used for intermediate C++ header files
generated by SWIG. These are only generated for C++ code when the
SWIG 'directors' feature is turned on. The default value is
_wrap.h.

SWIGFLAGS
General options passed to SWIG. This is where you should set the
target language (-python, -perl5, -tcl, etc.) and whatever other
options you want to specify to SWIG, such as the -c++ to generate
C++ code instead of C Code.

_SWIGINCFLAGS
An automatically-generated construction variable containing the
SWIG command-line options for specifying directories to be searched
for included files. The value of $_SWIGINCFLAGS is created by
respectively prepending and appending $SWIGINCPREFIX and
$SWIGINCSUFFIX to the beginning and end of each directory in
$SWIGPATH.

SWIGINCPREFIX
The prefix used to specify an include directory on the SWIG command
line. This will be prepended to the beginning of each directory in
the $SWIGPATH construction variable when the $_SWIGINCFLAGS
variable is automatically generated.

SWIGINCSUFFIX
The suffix used to specify an include directory on the SWIG command
line. This will be appended to the end of each directory in the
$SWIGPATH construction variable when the $_SWIGINCFLAGS variable is
automatically generated.

SWIGOUTDIR
Specifies the output directory in which SWIG should place generated
language-specific files. This will be used by SCons to identify the
files that will be generated by the SWIG call, and translated into
the swig -outdir option on the command line.

SWIGPATH
The list of directories that SWIG will search for included files.
SCons' SWIG implicit dependency scanner will search these
directories for include files. The default value is an empty list.

Don't explicitly put include directory arguments in $SWIGFLAGS the
result will be non-portable and the directories will not be
searched by the dependency scanner. Note: directory names in
$SWIGPATH will be looked-up relative to the SConscript directory
when they are used in a command. To force scons to look-up a
directory relative to the root of the source tree use a
top-relative path (#):

env = Environment(SWIGPATH='#/include')

The directory look-up can also be forced using the Dir() function:

include = Dir('include')
env = Environment(SWIGPATH=include)

The directory list will be added to command lines through the
automatically-generated $_SWIGINCFLAGS construction variable, which
is constructed by respectively prepending and appending the values
of the $SWIGINCPREFIX and $SWIGINCSUFFIX construction variables to
the beginning and end of each directory in $SWIGPATH. Any command
lines you define that need the SWIGPATH directory list should
include $_SWIGINCFLAGS:

env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SOURCES")

SWIGVERSION
The detected version string of the SWIG tool.

TAR
The tar archiver.

TARCOM
The command line used to call the tar archiver.

TARCOMSTR
The string displayed when archiving files using the tar archiver.
If this is not set, then $TARCOM (the command line) is displayed.

env = Environment(TARCOMSTR = "Archiving $TARGET")

TARFLAGS
General options passed to the tar archiver.

TARGET
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

TARGET_ARCH
The name of the hardware architecture that objects created using
this construction environment should target. Can be set when
creating a construction environment by passing as a keyword
argument in the Environment call.

On the win32 platform, if the Microsoft Visual C++ compiler is
available, msvc tool setup is done using $HOST_ARCH and
$TARGET_ARCH. If a value is not specified, will be set to the same
value as $HOST_ARCH. Changing the value after the environment is
initialized will not cause the tool to be reinitialized. Compiled
objects will be in the target architecture if the compilation
system supports generating for that target. The latest compiler
which can fulfill the requirement will be selected, unless a
different version is directed by the value of the $MSVC_VERSION
construction variable.

On the win32/msvc combination, valid target arch values are x86,
arm, i386 for 32-bit targets and amd64, arm64, x86_64 and ia64
(Itanium) for 64-bit targets. For example, if you want to compile
64-bit binaries, you would set TARGET_ARCH='x86_64' when creating
the construction environment. Note that not all target
architectures are supported for all Visual Studio / MSVC versions.
Check the relevant Microsoft documentation.

$TARGET_ARCH is not currently used by other compilation tools, but
the option is reserved to do so in future

TARGET_OS
The name of the operating system that objects created using this
construction environment should target. Can be set when creating a
construction environment by passing as a keyword argument in the
Environment call;.

$TARGET_OS is not currently used by SCons but the option is
reserved to do so in future

TARGETS
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

TARSUFFIX
The suffix used for tar file names.

TEMPFILE
A callable object used to handle overly long command line strings,
since operations which call out to a shell will fail if the line is
longer than the shell can accept. This tends to particularly impact
linking. The tempfile object stores the command line in a temporary
file in the appropriate format, and returns an alternate command
line so the invoked tool will make use of the contents of the
temporary file. If you need to replace the default tempfile object,
the callable should take into account the settings of
$MAXLINELENGTH, $TEMPFILEPREFIX, $TEMPFILESUFFIX, $TEMPFILEARGJOIN,
$TEMPFILEDIR and $TEMPFILEARGESCFUNC.

TEMPFILEARGESCFUNC
The default argument escape function is SCons.Subst.quote_spaces.
If you need to apply extra operations on a command argument (to fix
Windows slashes, normalize paths, etc.) before writing to the
temporary file, you can set the $TEMPFILEARGESCFUNC variable to a
custom function. Such a function takes a single string argument and
returns a new string with any modifications applied. Example:

import sys
import re
from SCons.Subst import quote_spaces

WINPATHSEP_RE = re.compile(r"\\([^\"'\\]|$)")

def tempfile_arg_esc_func(arg):
arg = quote_spaces(arg)
if sys.platform != "win32":
return arg
# GCC requires double Windows slashes, let's use UNIX separator
return WINPATHSEP_RE.sub(r"/\1", arg)

env["TEMPFILEARGESCFUNC"] = tempfile_arg_esc_func

TEMPFILEARGJOIN
The string to use to join the arguments passed to $TEMPFILE when
the command line exceeds the limit set by $MAXLINELENGTH. The
default value is a space. However for MSVC, MSLINK the default is a
line separator as defined by os.linesep. Note this value is used
literally and not expanded by the subst logic.

TEMPFILEDIR
The directory to create the long-lines temporary file in.

TEMPFILEPREFIX
The prefix for the name of the temporary file used to store command
lines exceeding $MAXLINELENGTH. The default prefix is '@', which
works for the Microsoft and GNU toolchains on Windows. Set this
appropriately for other toolchains, for example '-@' for the diab
compiler or '-via' for ARM toolchain.

TEMPFILESUFFIX
The suffix for the name of the temporary file used to store command
lines exceeding $MAXLINELENGTH. The suffix should include the dot
('.') if one is wanted as it will not be added automatically. The
default is .lnk.

TEX
The TeX formatter and typesetter.

TEXCOM
The command line used to call the TeX formatter and typesetter.

TEXCOMSTR
The string displayed when calling the TeX formatter and typesetter.
If this is not set, then $TEXCOM (the command line) is displayed.

env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

TEXFLAGS
General options passed to the TeX formatter and typesetter.

TEXINPUTS
List of directories that the LaTeX program will search for include
directories. The LaTeX implicit dependency scanner will search
these directories for \include and \import files.

TEXTFILEPREFIX
The prefix used for Textfile file names, an empty string by
default.

TEXTFILESUFFIX
The suffix used for Textfile file names; .txt by default.

TOOLS
A list of the names of the Tool specifications that are part of
this construction environment.

UNCHANGED_SOURCES
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

UNCHANGED_TARGETS
A reserved variable name that may not be set or used in a
construction environment. (See the manpage section "Variable
Substitution" for more information).

VENDOR
The person or organization who supply the packaged software. This
is used to fill in the Vendor: field in the controlling information
for RPM packages, and the Manufacturer: field in the controlling
information for MSI packages.

See the Package builder.

VERSION
The version of the project, specified as a string.

See the Package builder.

VSWHERE
Specify the location of vswhere.exe.

The vswhere.exe executable is distributed with Microsoft Visual
Studio and Build Tools since the 2017 edition, but is also
available standalone. It provides full information about
installations of 2017 and later editions. With the -legacy
argument, vswhere.exe can detect installations of the 2010 through
2015 editions with limited data returned. If VSWHERE is set, SCons
will use that location.

Otherwise SCons will look in the following locations and set
VSWHERE to the path of the first vswhere.exe located.

• %ProgramFiles(x86)%\Microsoft Visual Studio\Installer

• %ProgramFiles%\Microsoft Visual Studio\Installer

• %ChocolateyInstall%\bin

Note that VSWHERE must be set at the same time or prior to any of
msvc, msvs , and/or mslink Tool being initialized. Either set it as
follows

env = Environment(VSWHERE='c:/my/path/to/vswhere')

or if your construction environment is created specifying an empty
tools list (or a list of tools which omits all of default, msvs,
msvc, and mslink), and also before env.Tool is called to
ininitialize any of those tools:

env = Environment(tools=[])
env['VSWHERE'] = r'c:/my/vswhere/install/location/vswhere.exe'
env.Tool('msvc')
env.Tool('mslink')
env.Tool('msvs')

WINDOWS_EMBED_MANIFEST
Set to True to embed the compiler-generated manifest (normally
${TARGET}.manifest) into all Windows executables and DLLs built
with this environment, as a resource during their link step. This
is done using $MT and $MTEXECOM and $MTSHLIBCOM. See also
$WINDOWS_INSERT_MANIFEST.

WINDOWS_INSERT_DEF
If set to true, a library build of a Windows shared library (.dll
file) will include a reference to the corresponding
module-definition file at the same time, if a module-definition
file is not already listed as a build target. The name of the
module-definition file will be constructed from the base name of
the library and the construction variables $WINDOWSDEFSUFFIX and
$WINDOWSDEFPREFIX. The default is to not add a module-definition
file. The module-definition file is not created by this directive,
and must be supplied by the developer.

WINDOWS_INSERT_MANIFEST
If set to true, scons will add the manifest file generated by
Microsoft Visual C++ 8.0 and later to the target list so SCons will
be aware they were generated. In the case of an executable, the
manifest file name is constructed using $WINDOWSPROGMANIFESTSUFFIX
and $WINDOWSPROGMANIFESTPREFIX. In the case of a shared library,
the manifest file name is constructed using
$WINDOWSSHLIBMANIFESTSUFFIX and $WINDOWSSHLIBMANIFESTPREFIX. See
also $WINDOWS_EMBED_MANIFEST.

WINDOWSDEFPREFIX
The prefix used for a Windows linker module-definition file name.
Defaults to empty.

WINDOWSDEFSUFFIX
The suffix used for a Windows linker module-definition file name.
Defaults to .def.

WINDOWSEXPPREFIX
The prefix used for Windows linker exports file names. Defaults to
empty.

WINDOWSEXPSUFFIX
The suffix used for Windows linker exports file names. Defaults to
.exp.

WINDOWSPROGMANIFESTPREFIX
The prefix used for executable program manifest files generated by
Microsoft Visual C/C++. Defaults to empty.

WINDOWSPROGMANIFESTSUFFIX
The suffix used for executable program manifest files generated by
Microsoft Visual C/C++. Defaults to .manifest.

WINDOWSSHLIBMANIFESTPREFIX
The prefix used for shared library manifest files generated by
Microsoft Visual C/C++. Defaults to empty.

WINDOWSSHLIBMANIFESTSUFFIX
The suffix used for shared library manifest files generated by
Microsoft Visual C/C++. Defaults to .manifest.

X_IPK_DEPENDS
This is used to fill in the Depends: field in the controlling
information for Ipkg packages.

See the Package builder.

X_IPK_DESCRIPTION
This is used to fill in the Description: field in the controlling
information for Ipkg packages. The default value is
“$SUMMARY\n$DESCRIPTION”

X_IPK_MAINTAINER
This is used to fill in the Maintainer: field in the controlling
information for Ipkg packages.

X_IPK_PRIORITY
This is used to fill in the Priority: field in the controlling
information for Ipkg packages.

X_IPK_SECTION
This is used to fill in the Section: field in the controlling
information for Ipkg packages.

X_MSI_LANGUAGE
This is used to fill in the Language: attribute in the controlling
information for MSI packages.

See the Package builder.

X_MSI_LICENSE_TEXT
The text of the software license in RTF format. Carriage return
characters will be replaced with the RTF equivalent \\par.

See the Package builder.

X_MSI_UPGRADE_CODE
TODO

X_RPM_AUTOREQPROV
This is used to fill in the AutoReqProv: field in the RPM .spec
file.

See the Package builder.

X_RPM_BUILD
internal, but overridable

X_RPM_BUILDREQUIRES
This is used to fill in the BuildRequires: field in the RPM .spec
file. Note this should only be used on a host managed by rpm as the
dependencies will not be resolvable at build time otherwise.

X_RPM_BUILDROOT
internal, but overridable

X_RPM_CLEAN
internal, but overridable

X_RPM_CONFLICTS
This is used to fill in the Conflicts: field in the RPM .spec file.

X_RPM_DEFATTR
This value is used as the default attributes for the files in the
RPM package. The default value is “(-,root,root)”.

X_RPM_DISTRIBUTION
This is used to fill in the Distribution: field in the RPM .spec
file.

X_RPM_EPOCH
This is used to fill in the Epoch: field in the RPM .spec file.

X_RPM_EXCLUDEARCH
This is used to fill in the ExcludeArch: field in the RPM .spec
file.

X_RPM_EXLUSIVEARCH
This is used to fill in the ExclusiveArch: field in the RPM .spec
file.

X_RPM_EXTRADEFS
A list used to supply extra defintions or flags to be added to the
RPM .spec file. Each item is added as-is with a carriage return
appended. This is useful if some specific RPM feature not otherwise
anticipated by SCons needs to be turned on or off. Note if this
variable is omitted, SCons will by default supply the value
'%global debug_package %{nil}' to disable debug package generation.
To enable debug package generation, include this variable set
either to None, or to a custom list that does not include the
default line. Added in version 3.1.

env.Package(
NAME="foo",
...
X_RPM_EXTRADEFS=[
"%define _unpackaged_files_terminate_build 0"
"%define _missing_doc_files_terminate_build 0"
],
...
)

X_RPM_GROUP
This is used to fill in the Group: field in the RPM .spec file.

X_RPM_GROUP_lang
This is used to fill in the Group(lang): field in the RPM .spec
file. Note that lang is not literal and should be replaced by the
appropriate language code.

X_RPM_ICON
This is used to fill in the Icon: field in the RPM .spec file.

X_RPM_INSTALL
internal, but overridable

X_RPM_PACKAGER
This is used to fill in the Packager: field in the RPM .spec file.

X_RPM_POSTINSTALL
This is used to fill in the %post: section in the RPM .spec file.

X_RPM_POSTUNINSTALL
This is used to fill in the %postun: section in the RPM .spec file.

X_RPM_PREFIX
This is used to fill in the Prefix: field in the RPM .spec file.

X_RPM_PREINSTALL
This is used to fill in the %pre: section in the RPM .spec file.

X_RPM_PREP
internal, but overridable

X_RPM_PREUNINSTALL
This is used to fill in the %preun: section in the RPM .spec file.

X_RPM_PROVIDES
This is used to fill in the Provides: field in the RPM .spec file.

X_RPM_REQUIRES
This is used to fill in the Requires: field in the RPM .spec file.

X_RPM_SERIAL
This is used to fill in the Serial: field in the RPM .spec file.

X_RPM_URL
This is used to fill in the Url: field in the RPM .spec file.

XGETTEXT
Path to xgettext(1) program (found via Detect()). See xgettext tool
and POTUpdate builder.

XGETTEXTCOM
Complete xgettext command line. See xgettext tool and POTUpdate
builder.

XGETTEXTCOMSTR
A string that is shown when xgettext(1) command is invoked
(default: '', which means "print $XGETTEXTCOM"). See xgettext tool
and POTUpdate builder.

_XGETTEXTDOMAIN
Internal "macro". Generates xgettext domain name form source and
target (default: '${TARGET.filebase}').

XGETTEXTFLAGS
Additional flags to xgettext(1). See xgettext tool and POTUpdate
builder.

XGETTEXTFROM
Name of file containing list of xgettext(1)'s source files.
Autotools' users know this as POTFILES.in so they will in most
cases set XGETTEXTFROM="POTFILES.in" here. The $XGETTEXTFROM files
have same syntax and semantics as the well known GNU POTFILES.in.
See xgettext tool and POTUpdate builder.

_XGETTEXTFROMFLAGS
Internal "macro". Genrates list of -D<dir> flags from the
$XGETTEXTPATH list.

XGETTEXTFROMPREFIX
This flag is used to add single $XGETTEXTFROM file to xgettext(1)'s
commandline (default: '-f').

XGETTEXTFROMSUFFIX
(default: '')

XGETTEXTPATH
List of directories, there xgettext(1) will look for source files
(default: []).

Note
This variable works only together with $XGETTEXTFROM
See also xgettext tool and POTUpdate builder.

_XGETTEXTPATHFLAGS
Internal "macro". Generates list of -f<file> flags from
$XGETTEXTFROM.

XGETTEXTPATHPREFIX
This flag is used to add single search path to xgettext(1)'s
commandline (default: '-D').

XGETTEXTPATHSUFFIX
(default: '')

YACC
The parser generator.

YACC_GRAPH_FILE
If supplied, write a graph of the automaton to a file with the name
taken from this variable. Will be emitted as a --graph=
command-line option. Use this in preference to including --graph=
in $YACCFLAGS directly.

YACC_HEADER_FILE
If supplied, generate a header file with the name taken from this
variable. Will be emitted as a --header= command-line option. Use
this in preference to including --header= in $YACCFLAGS directly.

YACCCOM
The command line used to call the parser generator to generate a
source file.

YACCCOMSTR
The string displayed when generating a source file using the parser
generator. If this is not set, then $YACCCOM (the command line) is
displayed.

env = Environment(YACCCOMSTR="Yacc'ing $TARGET from $SOURCES")

YACCFLAGS
General options passed to the parser generator. In addition to
passing the value on during invocation, the yacc tool also examines
this construction variable for options which cause additional
output files to be generated, and adds those to the target list.

If a -d option is present, scons assumes that the call will also
create a header file with the suffix defined by $YACCHFILESUFFIX if
the yacc source file ends in a .y suffix, or a file with the suffix
defined by $YACCHXXFILESUFFIX if the yacc source file ends in a .yy
suffix.

If a -g option is present, scons assumes that the call will also
create a graph file with the suffix defined by $YACCVCGFILESUFFIX.

If a -v option is present, scons assumes that the call will also
create an output debug file with the suffix .output.

Also recognized are GNU bison options --header= and its deprecated
synonym --defines=, which is similar to -d but the output filename
is named by the option argument; and --graph=, which is similar to
-g but the output filename is named by the option argument.

Note that files specified by --header= and --graph= may not be
properly handled by SCons in all situations. Consider using
$YACC_HEADER_FILE and $YACC_GRAPH_FILE instead.

YACCHFILESUFFIX
The suffix of the C header file generated by the parser generator
when the -d option is used. Note that setting this variable does
not cause the parser generator to generate a header file with the
specified suffix, it exists to allow you to specify what suffix the
parser generator will use of its own accord. The default value is
.h.

YACCHXXFILESUFFIX
The suffix of the C++ header file generated by the parser generator
when the -d option is used. Note that setting this variable does
not cause the parser generator to generate a header file with the
specified suffix, it exists to allow you to specify what suffix the
parser generator will use of its own accord. The default value is
.hpp, except on Mac OS X, where the default is ${TARGET.suffix}.h.
because the default bison parser generator just appends .h to the
name of the generated C++ file.

YACCVCGFILESUFFIX
The suffix of the file containing the VCG grammar automaton
definition when the --graph= option is used. Note that setting this
variable does not cause the parser generator to generate a VCG file
with the specified suffix, it exists to allow you to specify what
suffix the parser generator will use of its own accord. The default
value is .vcg.

ZIP
The zip compression and file packaging utility.

ZIP_OVERRIDE_TIMESTAMP
An optional timestamp which overrides the last modification time of
the file when stored inside the Zip archive. This is a tuple of six
values: Year (>= 1980) Month (one-based) Day of month (one-based)
Hours (zero-based) Minutes (zero-based) Seconds (zero-based)

ZIPCOM
The command line used to call the zip utility, or the internal
Python function used to create a zip archive.

ZIPCOMPRESSION
The compression flag from the Python zipfile module used by the
internal Python function to control whether the zip archive is
compressed or not. The default value is zipfile.ZIP_DEFLATED, which
creates a compressed zip archive. This value has no effect if the
zipfile module is unavailable.

ZIPCOMSTR
The string displayed when archiving files using the zip utility. If
this is not set, then $ZIPCOM (the command line or internal Python
function) is displayed.

env = Environment(ZIPCOMSTR = "Zipping $TARGET")

ZIPFLAGS
General options passed to the zip utility.

ZIPROOT
An optional zip root directory (default empty). The filenames
stored in the zip file will be relative to this directory, if
given. Otherwise the filenames are relative to the current
directory of the command. For instance:

env = Environment()
env.Zip('foo.zip', 'subdir1/subdir2/file1', ZIPROOT='subdir1')

will produce a zip file foo.zip containing a file with the name
subdir2/file1 rather than subdir1/subdir2/file1.

ZIPSUFFIX
The suffix used for zip file names.

Configure Contexts
SCons supports a configure context, an integrated mechanism similar to
the various AC_CHECK macros in GNU Autoconf for testing the existence
of external items needed for the build, such as C header files,
libraries, etc. The mechanism is portable across platforms.

scons does not maintain an explicit cache of the tested values (this is
different than Autoconf), but uses its normal dependency tracking to
keep the checked values up to date. However, users may override this
behaviour with the --config command line option.

Configure(env, [custom_tests, conf_dir, log_file, config_h, clean,
help]), env.Configure([custom_tests, conf_dir, log_file, config_h,
clean, help])
Create a configure context, which tracks information discovered
while running tests. The context includes a local construction
environment (available as context.env) which is used when running
the tests and which can be updated with the check results. Only one
context may be active at a time (since 4.0, scons will raise an
exception on an attempt to create a new context when there is an
active context), but a new context can be created after the active
one is completed. For the global function form, the required env
describes the initial values for the context's local construction
environment; for the construction environment method form the
instance provides the values.

custom_tests specifies a dictionary containing custom tests (see
the section on custom tests below). The default value is None,
meaning no custom tests are added to the configure context.

conf_dir specifies a directory where the test cases are built. This
directory is not used for building normal targets. The default
value is “#/.sconf_temp”.

log_file specifies a file which collects the output from commands
that are executed to check for the existence of header files,
libraries, etc. The default is “#/config.log”. If you are using the
VariantDir function, you may want to specify a subdirectory under
your variant directory.

config_h specifies a C header file where the results of tests will
be written. The results will consist of lines like #define
HAVE_STDIO_H, #define HAVE_LIBM, etc. Customarily, the name chosen
is “config.h”. The default is to not write a config_h file. You can
specify the same config_h file in multiple calls to Configure, in
which case SCons will concatenate all results in the specified
file. Note that SCons uses its normal dependency checking to decide
if it's necessary to rebuild the specified config_h file. This
means that the file is not necessarily re-built each time scons is
run, but is only rebuilt if its contents will have changed and some
target that depends on the config_h file is being built.

The clean and help arguments can be used to suppress execution of
the configuration tests when the -c/--clean or -H/-h/--help options
are used, respectively. The default behavior is always to execute
configure context tests, since the results of the tests may affect
the list of targets to be cleaned or the help text. If the
configure tests do not affect these, then you may add the
clean=False or help=False arguments (or both) to avoid unnecessary
test execution.

context.Finish()
This method must be called after configuration is done. Though
required, this is not enforced except if Configure is called again
while there is still an active context, in which case an exception
is raised. Finish returns the environment as modified during the
course of running the configuration checks. After this method is
called, no further checks can be performed with this configuration
context. However, you can create a new configure context to perform
additional checks.

Example of a typical Configure usage:

env = Environment()
conf = Configure(env)
if not conf.CheckCHeader("math.h"):
print("We really need math.h!")
Exit(1)
if conf.CheckLibWithHeader("qt", "qapp.h", "c++", "QApplication qapp(0,0);"):
# do stuff for qt - usage, e.g.
conf.env.Append(CPPDEFINES="WITH_QT")
env = conf.Finish()

A configure context has the following predefined methods which can be
used to perform checks. Where language is a required or optional
parameter, the choice can currently be C or C++. The spellings accepted
for C are “C” or “c”; for C++ the value can be “CXX”, “cxx”, “C++” or
“c++”.

context.CheckHeader(header, [include_quotes, language])
Checks if header is usable in the specified language. header may
be a list, in which case the last item in the list is the header
file to be checked, and the previous list items are header files
whose #include lines should precede the header line being checked
for. The optional argument include_quotes must be a two character
string, where the first character denotes the opening quote and the
second character denotes the closing quote. By default, both
characters are " (double quote). The optional argument language
should be either C or C++ and selects the compiler to be used for
the check. Returns a boolean indicating success or failure.

context.CheckCHeader(header, [include_quotes])
Checks if header is usable when compiling a C language program.
header may be a list, in which case the last item in the list is
the header file to be checked, and the previous list items are
header files whose #include lines should precede the header line
being checked for. The optional argument include_quotes must be a
two character string, where the first character denotes the opening
quote and the second character denotes the closing quote. By
default, both characters are " (double quote). Note this is a
wrapper around CheckHeader. Returns a boolean indicating success or
failure.

context.CheckCXXHeader(header, [include_quotes])
Checks if header is usable when compiling a C++ language program.
header may be a list, in which case the last item in the list is
the header file to be checked, and the previous list items are
header files whose #include lines should precede the header line
being checked for. The optional argument include_quotes must be a
two character string, where the first character denotes the opening
quote and the second character denotes the closing quote. By
default, both characters are " (double quote). Note this is a
wrapper around CheckHeader. Returns a boolean indicating success or
failure.

context.CheckFunc(function_name, [header, language])
Checks if the specified C or C++ library function is available
based on the context's local environment settings (that is, using
the values of $CFLAGS, $CPPFLAGS, $LIBS or other relevant
construction variables).

function_name is the name of the function to check for. The
optional header argument is a string that will be placed at the top
of the test file that will be compiled to check if the function
exists; the default is:

#ifdef __cplusplus
extern "C"
#endif
char function_name();

Returns an empty string on success, a string containing an error
message on failure.

context.CheckLib([library, symbol, header, language, autoadd=True])
Checks if library provides symbol. If autoadd is true (the default)
and the library provides the specified symbol, appends the library
to the LIBS construction variable library may also be None (the
default), in which case symbol is checked with the current LIBS
variable, or a list of library names, in which case each library in
the list will be checked for symbol. If symbol is not set or is
None, then CheckLib just checks if you can link against the
specified library. Note though it is legal syntax, it would not be
very useful to call this method with library and symbol both
omitted or None. Returns a boolean indicating success or failure.

context.CheckLibWithHeader(library, header, language, [call,
autoadd=True])
Provides a more sophisticated way to check against libraries then
the CheckLib call. library specifies the library or a list of
libraries to check. header specifies a header to check for.
header may be a list, in which case the last item in the list is
the header file to be checked, and the previous list items are
header files whose #include lines should precede the header line
being checked for. call can be any valid expression (with a
trailing ';'). If call is not set, the default simply checks that
you can link against the specified library. autoadd (default true)
specifies whether to add the library to the environment if the
check succeeds. Returns a boolean indicating success or failure.

context.CheckType(type_name, [includes, language])
Checks for the existence of a type defined by typedef. type_name
specifies the typedef name to check for. includes is a string
containing one or more #include lines that will be inserted into
the program that will be run to test for the existence of the type.
Example:

sconf.CheckType('foo_type', '#include "my_types.h"', 'C++')

Returns an empty string on success, a string containing an error
message on failure.

context.CheckTypeSize(type_name, [header, language, expect])
Checks for the size of a type defined by typedef. type_name
specifies the typedef name to check for. The optional header
argument is a string that will be placed at the top of the test
file that will be compiled to check if the type exists; the default
is empty. If the optional expect, is supplied, it should be an
integer size; CheckTypeSize will fail unless type_name is actually
that size. Returns the size in bytes, or zero if the type was not
found (or if the size did not match expect).

For example,

CheckTypeSize('short', expect=2)

will return the size 2 only if short is actually two bytes.

context.CheckCC()
Checks whether the C compiler (as defined by the $CC construction
variable) works, by trying to compile a small source file. This
provides a more rigorous check: by default, SCons itself only
detects if there is a program with the correct name, not if it is a
functioning compiler. Returns a boolean indicating success or
failure.

The test program will be built with the same command line as the
one used by the Object builder for C source files, so by setting
relevant construction variables it can be used to detect if
particular compiler flags will be accepted or rejected by the
compiler.

context.CheckCXX()
Checks whether the C++ compiler (as defined by the $CXX
construction variable) works, by trying to compile a small source
file. This provides a more rigorous check: by default, SCons itself
only detects if there is a program with the correct name, not if it
is a functioning compiler. Returns a boolean indicating success or
failure.

The test program will be built with the same command line as the
one used by the Object builder for C++ source files, so by setting
relevant construction variables it can be used to detect if
particular compiler flags will be accepted or rejected by the
compiler.

context.CheckSHCC()
Checks whether the shared-object C compiler (as defined by the
$SHCC construction variable) works by trying to compile a small
source file. This provides a more rigorous check: by default, SCons
itself only detects if there is a program with the correct name,
not if it is a functioning compiler. Returns a boolean indicating
success or failure.

The test program will be built with the same command line as the
one used by the SharedObject builder for C source files, so by
setting relevant construction variables it can be used to detect if
particular compiler flags will be accepted or rejected by the
compiler. Note this does not check whether a shared library/dll can
be created.

context.CheckSHCXX()
Checks whether the shared-object C++ compiler (as defined by the
$SHCXX construction variable) works by trying to compile a small
source file. This provides a more rigorous check: by default, SCons
itself only detects if there is a program with the correct name,
not if it is a functioning compiler. Returns a boolean indicating
success or failure.

The test program will be built with the same command line as the
one used by the SharedObject builder for C++ source files, so by
setting relevant construction variables it can be used to detect if
particular compiler flags will be accepted or rejected by the
compiler. Note this does not check whether a shared library/dll can
be created.

context.CheckProg(prog_name)
Checks if prog_name exists in the path SCons will use at build
time. (context.env['ENV']['PATH']). Returns a string containing the
path to the program, or None on failure.

context.CheckDeclaration(symbol, [includes, language])
Checks if the specified symbol is declared. includes is a string
containing one or more #include lines that will be inserted into
the program that will be run to test for the existence of the
symbol. Returns a boolean indicating success or failure.

context.CheckMember(aggregate_member, [header, language])
Checks for the existence of a member of the C/C++ struct or class.
aggregate_member specifies the struct/class and member to check
for. header is a string containing one or more #include lines that
will be inserted into the program that will be run to test for the
existence of the member. Example:

sconf.CheckMember('struct tm.tm_sec', '#include <time.h>')

Returns a boolean indicating success or failure.

context.Define(symbol, [value, comment])
This method does not check for anything, but rather forces the
definition of a preprocessor macro that will be added to the
configuration header file. name is the macro's identifier. If
value is given, it will be be used as the macro replacement value.
If value is a string and needs to display with quotes, the quotes
need to be included, as in '"string"' If the optional comment is
given, it is inserted as a comment above the macro definition
(suitable comment marks will be added automatically). This is
analogous to using AC_DEFINE in Autoconf.

Examples:

env = Environment()
conf = Configure(env)

# Puts the following line in the config header file:
# #define A_SYMBOL
conf.Define("A_SYMBOL")

# Puts the following line in the config header file:
# #define A_SYMBOL 1
conf.Define("A_SYMBOL", 1)

Examples of quoting string values:

env = Environment()
conf = Configure(env)

# Puts the following line in the config header file:
# #define A_SYMBOL YA
conf.Define("A_SYMBOL", "YA")

# Puts the following line in the config header file:
# #define A_SYMBOL "YA"
conf.Define("A_SYMBOL", '"YA"')

Example including comment:

env = Environment()
conf = Configure(env)

# Puts the following lines in the config header file:
# /* Set to 1 if you have a symbol */
# #define A_SYMBOL 1
conf.Define("A_SYMBOL", 1, "Set to 1 if you have a symbol")

You can define your own custom checks in addition to using the
predefined checks. To enable custom checks, pass a dictionary to the
Configure function as the custom_tests parameter. The dictionary maps
the names of the checks to the custom check callables (either a Python
function or an instance of a class implementing a __call__ method).
Each custom check will be called with a a CheckContext instance as the
first parameter followed by the remaining arguments, which must be
supplied by the user of the check. A CheckContext is not the same as a
configure context; rather it is an instance of a class which contains a
configure context (available as chk_ctx.sconf). A CheckContext provides
the following methods which custom checks can make use of::

chk_ctx.Message(text)
Displays text as an indicator of progess. For example: Checking for
library X.... Usually called before the check is started.

chk_ctx.Result(res)
Displays a result message as an indicator of progress. If res is an
integer, displays yes if res evaluates true or no if false. If res
is a string, it is displayed as-is. Usually called after the check
has completed.

chk_ctx.TryCompile(text, extension='')
Checks if a file containing text and given the specified extension
(e.g. '.c') can be compiled to an object file using the
environment's Object builder. Returns a boolean indicating success
or failure.

chk_ctx.TryLink(text, extension='')
Checks if a file containing text and given the specified extension
(e.g. '.c') can be compiled to an executable program using the
environment's Program builder. Returns a boolean indicating success
or failure.

chk_ctx.TryRun(text, extension='')
Checks if a file containing text and given the specified extension
(e.g. '.c') can be compiled to an excutable program using the
environment's Program builder and subsequently executed. Execution
is only attempted if the build succeeds. If the program executes
successfully (that is, its return status is 0), a tuple (True,
outputStr) is returned, where outputStr is the standard output of
the program. If the program fails execution (its return status is
non-zero), then (False, '') is returned.

chk_ctx.TryAction(action, [text, extension=''])
Checks if the specified action with an optional source file
(contents text, given extension extension) can be executed. action
may be anything which can be converted to an Action Object. On
success, a tuple (True, outputStr) is returned, where outputStr is
the content of the target file. On failure (False, '') is returned.

chk_ctx.TryBuild(builder, [text, extension=''])
Low level implementation for testing specific builds; the methods
above are based on this method. Given the Builder instance builder
and the optional text of a source file with optional extension,
returns a boolean indicating success or failure. In addition,
chk_ctx.lastTarget is set to the build target node if the build was
successful.

Example of implementing and using custom tests:

def CheckQt(chk_ctx, qtdir):
chk_ctx.Message('Checking for qt ...')
lastLIBS = chk_ctx.env['LIBS']
lastLIBPATH = chk_ctx.env['LIBPATH']
lastCPPPATH = chk_ctx.env['CPPPATH']
chk_ctx.env.Append(LIBS='qt', LIBPATH=qtdir + '/lib', CPPPATH=qtdir + '/include')
ret = chk_ctx.TryLink(
"""\
#include <qapp.h>
int main(int argc, char **argv) {
QApplication qapp(argc, argv);
return 0;
}
"""
)
if not ret:
chkctx.env.Replace(LIBS=lastLIBS, LIBPATH=lastLIBPATH, CPPPATH=lastCPPPATH)
chkctx.Result(ret)
return ret

env = Environment()
conf = Configure(env, custom_tests={'CheckQt': CheckQt})
if not conf.CheckQt('/usr/lib/qt'):
print('We really need qt!')
Exit(1)
env = conf.Finish()

Command-Line Construction Variables
Often when building software, some variables need to be specified at
build time. For example, libraries needed for the build may be in
non-standard locations, or site-specific compiler options may need to
be passed to the compiler. SCons provides a Variables object to
support overriding construction variables with values obtained from
various sources, often from the command line:

scons VARIABLE=foo

The variable values can also be specified in a configuration file or an
SConscript file.

To obtain the object for manipulating values, call the Variables
function:

Variables([files, [args]])
If files is a file or list of files, they are executed as Python
scripts, and the values of (global) Python variables set in those
files are added as construction variables in the Default
Environment. If no files are specified, or the files argument is
None, then no files will be read (supplying None is necessary if
there are no files but you want to specify args as a positional
argument).

The following example file contents could be used to set an
alternative C compiler:

CC = 'my_cc'

If args is specified, it is a dictionary of values that will
override anything read from files. The primary use is to pass the
ARGUMENTS dictionary that holds variables specified on the command
line, allowing you to indicate that if a setting appears on both
the command line and in the file(s), the command line setting takes
precedence. However, any dictionary can be passed. Examples:

vars = Variables('custom.py')
vars = Variables('overrides.py', ARGUMENTS)
vars = Variables(None, {FOO:'expansion', BAR:7})

Calling Variables with no arguments is equivalent to:

vars = Variables(files=None, args=ARGUMENTS)

Note that since the variables are eventually added as construction
variables, you should choose variable names which do not
unintentionally change pre-defined construction variables that your
project will make use of (see the section called “Construction
Variables”).

Variables objects have the following methods:

vars.Add(key, [help, default, validator, converter])
Add a customizable construction variable to the Variables object.
key is either the name of the variable, or a tuple (or list), in
which case the first item in the tuple is taken as the variable
name, and any remaining values are considered aliases for the
variable. help is the help text for the variable (default empty
string). default is the default value of the variable (default
None). If default is None and a value is not specified, the
construction variable will not be added to the construction
environment.

As a special case, if key is a tuple (or list) and is the only
argument, the tuple is unpacked into the five parameters listed
above left to right, with any missing members filled with the
respecitive default values. This form allows Add to consume a tuple
emitted by the convenience functions BoolVariable, EnumVariable,
ListVariable, PackageVariable and PathVariable.

If the optional validator is supplied, it is called to validate the
value of the variable. A function supplied as a validator must
accept three arguments: key, value and env, and should raise an
exception with a helpful error message if value is invalid. No
return value is expected from the validator.

If the optional converter is supplied, it is called to convert the
value before putting it in the environment, and should take either
a value or a value and environment as parameters. The converter
function must return a value, which will be converted into a string
and be passed to the validator (if any) and then added to the
construction environment.

Examples:

vars.Add('CC', help='The C compiler')

def valid_color(key, val, env):
if not val in ['red', 'blue', 'yellow']:
raise Exception("Invalid color value '%s'" % val)

vars.Add('COLOR', validator=valid_color)

vars.AddVariables(args)
A convenience method that adds one or more customizable
construction variables to a Variables object in one call;
equivalent to calling Add multiple times. The args are tuples (or
lists) that contain the arguments for an individual call to the Add
method. Since tuples are not Python mappings, the arguments cannot
use the keyword form, but rather are positional arguments as
documented for Add: a required name, the other four optional, but
must be in the specified order if used.

opt.AddVariables(
("debug", "", 0),
("CC", "The C compiler"),
("VALIDATE", "An option for testing validation", "notset", validator, None),
)

vars.Update(env, [args])
Update a construction environment env with the customized
construction variables. Any specified variables that are not
configured for the Variables object will be saved and may be
retrieved using the UnknownVariables method.

Normally this method is not called directly, but rather invoked
indirectly by passing the Variables object to the Environment
function:

env = Environment(variables=vars)

vars.UnknownVariables()
Returns a dictionary containing any variables that were specified
either in the files or the dictionary with which the Variables
object was initialized, but for which the Variables object was not
configured.

env = Environment(variables=vars)
for key, value in vars.UnknownVariables():
print("unknown variable: %s=%s" % (key, value))

vars.Save(filename, env)
Save the currently set variables into a script file named by
filename. Only variables that are set to non-default values are
saved. You can load these saved settings on a subsequent run by
passing filename to the Variables function, providing a way to
cache particular settings for reuse.

env = Environment()
vars = Variables(['variables.cache', 'custom.py'])
vars.Add(...)
vars.Update(env)
vars.Save('variables.cache', env)

vars.GenerateHelpText(env, [sort])
Generate help text documenting the customizable construction
variables, suitable for passing in to the Help function. env is
the construction environment that will be used to get the actual
values of the customizable variables. If the (optional) value of
sort is callable, it is used as a comparison function to determine
how to sort the added variables. This function must accept two
arguments, compare them, and return a negative integer if the first
is less-than the second, zero for equality, or a positive integer
for greater-than. Optionally a Boolean value of True for sort will
cause a standard alphabetical sort to be performed.

Help(vars.GenerateHelpText(env))

def cmp(a, b):
return (a > b) - (a < b)

Help(vars.GenerateHelpText(env, sort=cmp))

vars.FormatVariableHelpText(env, opt, help, default, actual)
Returns a formatted string containing the printable help text for
one option. It is normally not called directly, but is called by
the GenerateHelpText method to create the returned help text. It
may be overridden with your own function that takes the arguments
specified above and returns a string of help text formatted to your
liking. Note that GenerateHelpText will not put any blank lines or
extra characters in between the entries, so you must add those
characters to the returned string if you want the entries
separated.

def my_format(env, opt, help, default, actual):
fmt = "\n%s: default=%s actual=%s (%s)\n"
return fmt % (opt, default, actual, help)

vars.FormatVariableHelpText = my_format

To make it more convenient to work with customizable Variables, scons
provides a number of functions that make it easy to set up various
types of Variables. Each of these return a tuple ready to be passed to
the Add or AddVariables method:

BoolVariable(key, help, default)
Returns a tuple of arguments to set up a Boolean option. The option
will use the specified name key, have a default value of default,
and help will form the descriptive part of the help text. The
option will interpret the values y, yes, t, true, 1, on and all as
true, and the values n, no, f, false, 0, off and none as false.

EnumVariable(key, help, default, allowed_values, [map, ignorecase])
Returns a tuple of arguments to set up an option whose value may be
one of a specified list of legal enumerated values. The option will
use the specified name key, have a default value of default, and
help will form the descriptive part of the help text. The option
will only support those values in the allowed_values list. The
optional map argument is a dictionary that can be used to convert
input values into specific legal values in the allowed_values list.
If the value of ignore_case is 0 (the default), then the values are
case-sensitive. If the value of ignore_case is 1, then values will
be matched case-insensitively. If the value of ignore_case is 2,
then values will be matched case-insensitively, and all input
values will be converted to lower case.

ListVariable(key, help, default, names, [map])
Returns a tuple of arguments to set up an option whose value may be
one or more of a specified list of legal enumerated values. The
option will use the specified name key, have a default value of
default, and help will form the descriptive part of the help text.
The option will only accept the values “all”, “none”, or the values
in the names list. More than one value may be specified, separated
by commas. The default may be a string of comma-separated default
values, or a list of the default values. The optional map argument
is a dictionary that can be used to convert input values into
specific legal values in the names list. (Note that the additional
values accepted through the use of a map are not reflected in the
generated help message).

PackageVariable(key, help, default)
Returns a tuple of arguments to set up an option whose value is a
path name of a package that may be enabled, disabled or given an
explicit path name. The option will use the specified name key,
have a default value of default, and help will form the descriptive
part of the help text. The option will support the values yes,
true, on, enable or search, in which case the specified default
will be used, or the option may be set to an arbitrary string
(typically the path name to a package that is being enabled). The
option will also support the values no, false, off or disable to
disable use of the specified option.

PathVariable(key, help, default, [validator])
Returns a tuple of arguments to set up an option whose value is
expected to be a path name. The option will use the specified name
key, have a default value of default, and help will form the
descriptive part of the help text. An additional validator may be
specified that will be called to verify that the specified path is
acceptable. SCons supplies the following ready-made validators:

PathVariable.PathExists
Verify that the specified path exists (this the default
behavior if no validator is supplied).

PathVariable.PathIsFile
Verify that the specified path exists and is a regular file.

PathVariable.PathIsDir
Verify that the specified path exists and is a directory.

PathVariable.PathIsDirCreate
Verify that the specified path exists and is a directory; if it
does not exist, create the directory.

PathVariable.PathAccept
Accept the specific path name argument without validation,
suitable for when you want your users to be able to specify a
directory path that will be created as part of the build
process, for example.

You may supply your own validator function, which must accept three
arguments (key, the name of the variable to be set; val, the
specified value being checked; and env, the construction
environment) and should raise an exception if the specified value
is not acceptable.

These functions make it convenient to create a number of variables with
consistent behavior in a single call to the AddVariables method:

vars.AddVariables(
BoolVariable(
"warnings",
help="compilation with -Wall and similar",
default=1,
),
EnumVariable(
"debug",
help="debug output and symbols",
default="no",
allowed_values=("yes", "no", "full"),
map={},
ignorecase=0, # case sensitive
),
ListVariable(
"shared",
help="libraries to build as shared libraries",
default="all",
names=list_of_libs,
),
PackageVariable(
"x11",
help="use X11 installed here (yes = search some places)",
default="yes",
),
PathVariable(
"qtdir",
help="where the root of Qt is installed",
default=qtdir),
PathVariable(
"foopath",
help="where the foo library is installed",
default=foopath,
validator=PathVariable.PathIsDir,
),
)

Node Objects
SCons represents objects that are the sources or targets of build
operations as Nodes, which are internal data structures. There are a
number of user-visible types of nodes: File Nodes, Directory Nodes,
Value Nodes and Alias Nodes. Some of the node types have public
attributes and methods, described below. Each of the node types has a
global function and a matching environment method to create instances:
File, Dir, Value and Alias.

Filesystem Nodes
The File and Dir functions/methods return File and Directory Nodes,
respectively. File and Directory Nodes (collectively, Filesystem
Nodes) represent build components that correspond to an entry in
the computer's filesystem, whether or not such an entry exists at
the time the Node is created. You do not usually need to explicitly
create filesystem Nodes, since when you supply a string as a target
or source of a Builder, SCons will create the Nodes as needed to
populate the dependency graph. Builders return the target Node(s)
in the form of a list, which you can then make use of. However,
since filesystem Nodes have some useful public attributes and
methods that you can use in SConscript files, it is sometimes
appropriate to create them manually, outside the regular context of
a Builder call.

The following attributes provide information about a Node:

node.path
The build path of the given file or directory. This path is
relative to the top-level directory (where the SConstruct file
is found). The build path is the same as the source path if
variant_dir is not being used.

node.abspath
The absolute build path of the given file or directory.

node.relpath
The build path of the given file or directory relative to the
root SConstruct file's directory.

node.srcnode()
The srcnode method returns another File or Directory Node
representing the source path of the given File or Directory
Node.

Examples:

# Get the current build dir's path, relative to top.
Dir('.').path

# Current dir's absolute path
Dir('.').abspath

# Current dir's path relative to the root SConstruct file's directory
Dir('.').relpath

# Next line is always '.', because it is the top dir's path relative to itself.
Dir('#.').path

# Source path of the given source file.
File('foo.c').srcnode().path

# Builders return lists of File objects:
foo = env.Program('foo.c')
print("foo will be built in", foo[0].path)

Filesystem Node objects have methods to create new File and
Directory Nodes relative to the original Node. There are also times
when you may need to refer to an entry in a filesystem without
knowing in advance whether it's a file or a directory. For those
situations, there is an Entry method of filesystem node objects,
which returns a Node that can represent either a file or a
directory.

If the original Node is a Directory Node, these methods will place
the new Node within the directory the original Node represents:

node.Dir(name)
Returns a directory Node name which is a subdirectory of the
directory represented by node.

node.File(name)
Returns a file Node name in the directory represented by node.

node.Entry(name)
Returns an unresolved Node name in the directory represented by
node.

If the original Node is a File Node, these methods will place the
the new Node in the same directory as the one the original Node
represents:

node.Dir(name)
Returns a Node name for a directory in the parent directory of
the file represented by node.

node.File(name)
Returns a Node name for a file in the parent directory of the
file represented by node.

node.Entry(name)
Returns an unresolved Node name in the parent directory of the
file represented by node.

For example:

# Get a Node for a file within a directory
incl = Dir('include')
f = incl.File('header.h')

# Get a Node for a subdirectory within a directory
dist = Dir('project-3.2.1')
src = dist.Dir('src')

# Get a Node for a file in the same directory
cfile = File('sample.c')
hfile = cfile.File('sample.h')

# Combined example
docs = Dir('docs')
html = docs.Dir('html')
index = html.File('index.html')
css = index.File('app.css')

Value and Alias Nodes
SCons provides two other Node types to represent object that will
not have an equivalent filesystem entry. Such Nodes always need to
be created explicitly.

The Alias method returns an Alias Node. Aliases are virtual objects
- they will not themselves result in physical objects being
constructed, but are entered into the dependency graph related to
their sources. An alias is checked for up to date by checking if
its sources are up to date. An alias is built by making sure its
sources have been built, and if any building took place, applying
any Actions that are defined as part of the alias.

An Alias call creates an entry in the alias namespace, which is
used for disambiguation. If an alias source has a string valued
name, it will be resolved to a filesystem entry Node, unless it is
found in the alias namespace, in which case it it resolved to the
matching alias Node. As a result, the order of Alias calls is
significant. An alias can refer to another alias, but only if the
other alias has previously been created.

The Value method returns a Value Node. Value nodes are often used
for generated data that will not have any corresponding filesystem
entry, but will be used to determine whether a build target is out
of date, or to include as part of a build Action. Common examples
are timestamp strings, revision control version strings and other
run-time generated strings.

A Value Node can also be the target of a builder.

EXTENDING SCONS
SCons is designed to be extensible through provided facilities, so
changing the code of SCons itself is only rarely needed to customize
its behavior. A number of the main operations use callable objects
which can be supplemented by writing your own. Builders, Scanners and
Tools each use a kind of plugin system, allowing you to easily drop in
new ones. Information about creating Builder Objects and Scanner
Objects appear in the following sections. The instructions SCons
actually uses to construct things are called Actions, and it is easy to
create Action Objects and hand them to the objects that need to know
about those actions (besides Builders, see AddPostAction, AddPreAction
and Alias for some examples of other places that take Actions). Action
Objects are also described below. Adding new Tool modules is described
in Tool Modules

Builder Objects
scons can be extended to build different types of targets by adding new
Builder objects to a construction environment. In general, you should
only need to add a new Builder object when you want to build a new type
of file or other external target. For output file types scons already
knows about, you can usually modify the behavior of premade Builders
such as Program, Object or Library by changing the construction
variables they use ($CC, $LINK, etc.). In this manner you can, for
example, change the compiler to use, which is simpler and less
error-prone than writing a new builder. The documentation for each
Builder lists which construction variables it uses.

Builder objects are created using the Builder factory function. Once
created, a builder is added to an environment by entering it in the
$BUILDERS dictionary in that environment (some of the examples in this
section illustrate this). Doing so automatically triggers SCons to add
a method with the name of the builder to the environment.

The Builder function accepts the following keyword arguments:

action
The command used to build the target from the source. action may
be a string representing a template command line to execute, a list
of strings representing the command to execute with its arguments
(suitable for enclosing white space in an argument), a dictionary
mapping source file name suffixes to any combination of command
line strings (if the builder should accept multiple source file
extensions), a Python function, an Action object (see Action
Objects) or a list of any of the above.

An action function must accept three arguments: source, target and
env. source is a list of source nodes; target is a list of target
nodes; env is the construction environment to use for context.

The action and generator arguments must not both be used for the
same Builder.

prefix
The prefix to prepend to the target file name. prefix may be a
string, a function (or other callable) that takes two arguments (a
construction environment and a list of sources) and returns a
prefix string, or a dictionary specifying a mapping from a specific
source suffix (of the first source specified) to a corresponding
target prefix string. For the dictionary form, both the source
suffix (key) and target prefix (value) specifications may use
environment variable substitution, and the target prefix may also
be a callable object. The default target prefix may be indicated by
a dictionary entry with a key of None.

b = Builder("build_it < $SOURCE > $TARGET",
prefix="file-")

def gen_prefix(env, sources):
return "file-" + env['PLATFORM'] + '-'

b = Builder("build_it < $SOURCE > $TARGET",
prefix=gen_prefix)

b = Builder("build_it < $SOURCE > $TARGET",
suffix={None: "file-", "$SRC_SFX_A": gen_prefix})

suffix
The suffix to append to the target file name. Specified in the same
manner as for prefix above. If the suffix is a string, then scons
prepends a '.' to the suffix if it's not already there. The string
returned by the callable object or obtained from the dictionary is
untouched and you need to manually prepend a '.' if one is
required.

b = Builder("build_it < $SOURCE > $TARGET"
suffix="-file")

def gen_suffix(env, sources):
return "." + env['PLATFORM'] + "-file"

b = Builder("build_it < $SOURCE > $TARGET",
suffix=gen_suffix)

b = Builder("build_it < $SOURCE > $TARGET",
suffix={None: ".sfx1", "$SRC_SFX_A": gen_suffix})

ensure_suffix
If set to a true value, ensures that targets will end in suffix.
Thus, the suffix will also be added to any target strings that have
a suffix that is not already suffix. The default behavior (also
indicated by a false value) is to leave unchanged any target string
that looks like it already has a suffix.

b1 = Builder("build_it < $SOURCE > $TARGET"
suffix = ".out")
b2 = Builder("build_it < $SOURCE > $TARGET"
suffix = ".out",
ensure_suffix=True)
env = Environment()
env['BUILDERS']['B1'] = b1
env['BUILDERS']['B2'] = b2

# Builds "foo.txt" because ensure_suffix is not set.
env.B1('foo.txt', 'foo.in')

# Builds "bar.txt.out" because ensure_suffix is set.
env.B2('bar.txt', 'bar.in')

src_suffix
The expected source file name suffix. src_suffix may be a string
or a list of strings.

target_scanner
A Scanner object that will be invoked to find implicit dependencies
for this target file. This keyword argument should be used for
Scanner objects that find implicit dependencies based only on the
target file and the construction environment, not for implicit
dependencies based on source files. See the section called “Scanner
Objects” for information about creating Scanner objects.

source_scanner
A Scanner object that will be invoked to find implicit dependencies
in any source files used to build this target file. This is where
you would specify a scanner to find things like #include lines in
source files. The pre-built DirScanner Scanner object may be used
to indicate that this Builder should scan directory trees for
on-disk changes to files that scons does not know about from other
Builder or function calls. See the section called “Scanner Objects”
for information about creating your own Scanner objects.

target_factory
A factory function that the Builder will use to turn any targets
specified as strings into SCons Nodes. By default, SCons assumes
that all targets are files. Other useful target_factory values
include Dir, for when a Builder creates a directory target, and
Entry, for when a Builder can create either a file or directory
target.

Example:

MakeDirectoryBuilder = Builder(action=my_mkdir, target_factory=Dir)
env = Environment()
env.Append(BUILDERS={'MakeDirectory': MakeDirectoryBuilder})
env.MakeDirectory('new_directory', [])

Note that the call to this MakeDirectory Builder needs to specify
an empty source list to make the string represent the builder's
target; without that, it would assume the argument is the source,
and would try to deduce the target name from it, which in the
absence of an automatically-added prefix or suffix would lead to a
matching target and source name and a circular dependency.

source_factory
A factory function that the Builder will use to turn any sources
specified as strings into SCons Nodes. By default, SCons assumes
that all source are files. Other useful source_factory values
include Dir, for when a Builder uses a directory as a source, and
Entry, for when a Builder can use files or directories (or both) as
sources.

Example:

CollectBuilder = Builder(action=my_mkdir, source_factory=Entry)
env = Environment()
env.Append(BUILDERS={'Collect': CollectBuilder})
env.Collect('archive', ['directory_name', 'file_name'])

emitter
A function or list of functions to manipulate the target and source
lists before dependencies are established and the target(s) are
actually built. emitter can also be a string containing a
construction variable to expand to an emitter function or list of
functions, or a dictionary mapping source file suffixes to emitter
functions. (Only the suffix of the first source file is used to
select the actual emitter function from an emitter dictionary.)

A function passed as emitter must accept three arguments: source,
target and env. source is a list of source nodes, target is a list
of target nodes, env is the construction environment to use for
context.

An emitter must return a tuple containing two lists, the list of
targets to be built by this builder, and the list of sources for
this builder.

Example:

def e(target, source, env):
return target + ['foo.foo'], source + ['foo.src']

# Simple association of an emitter function with a Builder.
b = Builder("my_build < $TARGET > $SOURCE", emitter=e)

def e2(target, source, env):
return target + ['bar.foo'], source + ['bar.src']

# Simple association of a list of emitter functions with a Builder.
b = Builder("my_build < $TARGET > $SOURCE", emitter=[e, e2])

# Calling an emitter function through a construction variable.
env = Environment(MY_EMITTER=e)
b = Builder("my_build < $TARGET > $SOURCE", emitter='$MY_EMITTER')

# Calling a list of emitter functions through a construction variable.
env = Environment(EMITTER_LIST=[e, e2])
b = Builder("my_build < $TARGET > $SOURCE", emitter='$EMITTER_LIST')

# Associating multiple emitters with different file
# suffixes using a dictionary.
def e_suf1(target, source, env):
return target + ['another_target_file'], source

def e_suf2(target, source, env):
return target, source + ['another_source_file']

b = Builder(
action="my_build < $TARGET > $SOURCE",
emitter={'.suf1': e_suf1, '.suf2': e_suf2}
)

multi
Specifies whether this builder is allowed to be called multiple
times for the same target file(s). The default is False, which
means the builder can not be called multiple times for the same
target file(s). Calling a builder multiple times for the same
target simply adds additional source files to the target; it is not
allowed to change the environment associated with the target,
specify additional environment overrides, or associate a different
builder with the target.

env
A construction environment that can be used to fetch source code
using this Builder. (Note that this environment is not used for
normal builds of normal target files, which use the environment
that was used to call the Builder for the target file.)

generator
A function that returns a list of actions that will be executed to
build the target(s) from the source(s). The returned action(s) may
be an Action object, or anything that can be converted into an
Action object (see the next section).

A function passed as generator must accept four arguments: source,
target, env and for_signature. source is a list of source nodes,
target is a list of target nodes, env is the construction
environment to use for context, and for_signature is a Boolean
value that tells the function if it is being called for the purpose
of generating a build signature (as opposed to actually executing
the command). Since the build signature is used for rebuild
determination, the function should omit those elements that do not
affect whether a rebuild should be triggered if for_signature is
true.

Example:

def g(source, target, env, for_signature):
return [["gcc", "-c", "-o"] + target + source]

b = Builder(generator=g)

The generator and action arguments must not both be used for the
same Builder.

src_builder
Specifies a builder to use when a source file name suffix does not
match any of the suffixes of the builder. Using this argument
produces a multi-stage builder.

single_source
Specifies that this builder expects exactly one source file per
call. Giving more than one source file without target files results
in implicitly calling the builder multiple times (once for each
source given). Giving multiple source files together with target
files results in a UserError exception.

source_ext_match
When the specified action argument is a dictionary, the default
behavior when a builder is passed multiple source files is to make
sure that the extensions of all the source files match. If it is
legal for this builder to be called with a list of source files
with different extensions, this check can be suppressed by setting
source_ext_match to False or some other non-true value. In this
case, scons will use the suffix of the first specified source file
to select the appropriate action from the action dictionary.

In the following example, the setting of source_ext_match prevents
scons from exiting with an error due to the mismatched suffixes of
foo.in and foo.extra.

b = Builder(action={'.in' : 'build $SOURCES > $TARGET'},
source_ext_match=False)

env = Environment(BUILDERS={'MyBuild':b})
env.MyBuild('foo.out', ['foo.in', 'foo.extra'])

b = Builder(action="build < $SOURCE > $TARGET")
env = Environment(BUILDERS={'MyBuild' : b})
env.MyBuild('foo.out', 'foo.in', my_arg='xyzzy')

chdir
A directory from which scons will execute the action(s) specified
for this Builder. If the chdir argument is a string or a directory
Node, scons will change to the specified directory. If the chdir is
not a string or Node and is non-zero, then scons will change to the
target file's directory.

Note that scons will not automatically modify its expansion of
construction variables like $TARGET and $SOURCE when using the
chdir keyword argument--that is, the expanded file names will still
be relative to the top-level directory containing the SConstruct
file, and consequently incorrect relative to the chdir directory.
Builders created using chdir keyword argument, will need to use
construction variable expansions like ${TARGET.file} and
${SOURCE.file} to use just the filename portion of the targets and
source.

b = Builder(action="build < ${SOURCE.file} > ${TARGET.file}",
chdir=1)
env = Environment(BUILDERS={'MyBuild' : b})
env.MyBuild('sub/dir/foo.out', 'sub/dir/foo.in')

Warning
Python only keeps one current directory location even if there
are multiple threads. This means that use of the chdir argument
will not work with the SCons -j option, because individual
worker threads spawned by SCons interfere with each other when
they start changing directory.

Any additional keyword arguments supplied when a Builder object is
created (that is, when the Builder function is called) will be set in
the executing construction environment when the Builder object is
called. The canonical example here would be to set a construction
variable to the repository of a source code system.

Any such keyword arguments supplied when a Builder object is called
will only be associated with the target created by that particular
Builder call (and any other files built as a result of the call). These
extra keyword arguments are passed to the following functions: command
generator functions, function Actions, and emitter functions.

Action Objects
The Builder factory function will turn its action keyword argument into
an appropriate internal Action object, as will the Command function.
You can also explicitly create Action objects for passing to Builder,
or other functions that take actions as arguments, by calling the
Action factory function. This may more efficient when multiple Builder
objects need to do the same thing rather than letting each of those
Builder objects create a separate Action object. It also allows more
flexible configuration of an Action object. For example, to control the
message printed when the action is taken you need to create the action
object using Action.

The Action factory function returns an appropriate object for the
action represented by the type of the action argument (the first
positional parameter):

• If action is already an Action object, the object is simply
returned.

• If action is a string, a command-line Action is returned. If such a
string begins with @, the command line is not printed. If the
string begins with hyphen (-), the exit status from the specified
command is ignored, allowing execution to continue even if the
command reports failure:

Action('$CC -c -o $TARGET $SOURCES')

# Doesn't print the line being executed.
Action('@build $TARGET $SOURCES')

# Ignores return value
Action('-build $TARGET $SOURCES')

• If action is a list, then a list of Action objects is returned. An
Action object is created as necessary for each element in the list.
If an element within the list is itself a list, the embedded list
is taken as the command and arguments to be executed via the
command line. This allows white space to be enclosed in an argument
rather than taken as a separator by defining a command in a list
within a list:

Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']])

• If action is a callable object, a Function Action is returned. The
callable must accept three keyword arguments: target, source and
env. target is a Node object representing the target file, source
is a Node object representing the source file and env is the
construction environment used for building the target file.

The target and source arguments may be lists of Node objects if
there is more than one target file or source file. The actual
target and source file name(s) may be retrieved from their Node
objects via the built-in Python str function:

target_file_name = str(target)
source_file_names = [str(x) for x in source]

The function should return 0 or None to indicate a successful build
of the target file(s). The function may raise an exception or
return a non-zero exit status to indicate an unsuccessful build.

def build_it(target=None, source=None, env=None):
# build the target from the source
return 0

a = Action(build_it)

• If action is not one of the above types, no action object is
generated and Action returns None.

The environment method form env.Action will expand construction
variables in any argument strings, including action, at the time it is
called, using the construction variables in the construction
environment through which it was called. The global function form
Action delays variable expansion until the Action object is actually
used.

The optional second argument to Action is used to control the output
which is printed when the Action is actually performed. If this
parameter is omitted, or if the value is an empty string, a default
output depending on the type of the action is used. For example, a
command-line action will print the executed command. The following
argument types are accepted:

• If the second argument is a string, or if the cmdstr keyword
argument is supplied, the string defines what is printed.
Substitution is performed on the string before it is printed. The
string typically contains substitutable variables, notably
$TARGET(S) and $SOURCE(S), or consists of just a single variable
which is optionally defined somewhere else. SCons itself heavily
uses the latter variant.

• If the second argument is a function, or if the strfunction keyword
argument is supplied, the function will be called to obtain the
string to be printed when the action is performed. The function
must accept three keyword arguments: target, source and env, with
the same interpretation as for a callable action argument above.
The function is responsible for handling any required
substitutions.

• If the second argument is None, or if cmdstr=None is supplied,
output is suppressed entirely.

The cmdstr and strfunction keyword arguments may not both be supplied
in a single call to Action

Printing of action strings is affected by the setting of
$PRINT_CMD_LINE_FUNC.

Examples:

def build_it(target, source, env):
# build the target from the source
return 0

def string_it(target, source, env):
return "building '%s' from '%s'" % (target[0], source[0])

# Use a positional argument.
f = Action(build_it, string_it)
s = Action(build_it, "building '$TARGET' from '$SOURCE'")

# Alternatively, use a keyword argument.
f = Action(build_it, strfunction=string_it)
s = Action(build_it, cmdstr="building '$TARGET' from '$SOURCE'")

# You can provide a configurable variable.
l = Action(build_it, '$STRINGIT')

Any additional positional arguments, if present, may either be
construction variables or lists of construction variables whose values
will be included in the signature of the Action (the build signature)
when deciding whether a target should be rebuilt because the action
changed. Such variables may also be specified using the varlist keyword
parameter; both positional and keyword forms may be present, and will
be combined. This is necessary whenever you want a target to be rebuilt
when a specific construction variable changes. This is not often needed
for a string action, as the expanded variables will normally be part of
the command line, but may be needed if a Python function action uses
the value of a construction variable when generating the command line.

def build_it(target, source, env):
# build the target from the 'XXX' construction variable
with open(target[0], 'w') as f:
f.write(env['XXX'])
return 0

# Use positional arguments.
a = Action(build_it, '$STRINGIT', ['XXX'])

# Alternatively, use a keyword argument.
a = Action(build_it, varlist=['XXX'])

The Action factory function can be passed the following optional
keyword arguments to modify the Action object's behavior:

chdir
If chdir is true (the default is False), SCons will change
directories before executing the action. If the value of chdir is a
string or a directory Node, SCons will change to the specified
directory. Otherwise, if chdir evaluates true, SCons will change to
the target file's directory.

Note that SCons will not automatically modify its expansion of
construction variables like $TARGET and $SOURCE when using the
chdir parameter - that is, the expanded file names will still be
relative to the top-level directory containing the SConstruct file,
and consequently incorrect relative to the chdir directory.
Builders created using chdir keyword argument, will need to use
construction variable expansions like ${TARGET.file} and
${SOURCE.file} to use just the filename portion of the targets and
source. Example:

a = Action("build < ${SOURCE.file} > ${TARGET.file}", chdir=True)

exitstatfunc
If provided, must be a callable which accepts a single parameter,
the exit status (or return value) from the specified action, and
which returns an arbitrary or modified value. This can be used, for
example, to specify that an Action object's return value should be
ignored under special conditions and SCons should, therefore,
consider that the action always succeeds. Example:

def always_succeed(s):
# Always return 0, which indicates success.
return 0

a = Action("build < ${SOURCE.file} > ${TARGET.file}",
exitstatfunc=always_succeed)

batch_key
If provided, indicates that the Action can create multiple target
files by processing multiple independent source files
simultaneously. (The canonical example is "batch compilation" of
multiple object files by passing multiple source files to a single
invocation of a compiler such as Microsoft's Visual C / C++
compiler.) If the batch_key argument evaluates True and is not a
callable object, the configured Action object will cause scons to
collect all targets built with the Action object and configured
with the same construction environment into single invocations of
the Action object's command line or function. Command lines will
typically want to use the $CHANGED_SOURCES construction variable
(and possibly $CHANGED_TARGETS as well) to only pass to the command
line those sources that have actually changed since their targets
were built. Example:

a = Action('build $CHANGED_SOURCES', batch_key=True)

The batch_key argument may also be a callable function that returns
a key that will be used to identify different "batches" of target
files to be collected for batch building. A batch_key function must
accept four parameters: action, env, target and source. The first
parameter, action, is the active action object. The second
parameter, env, is the construction environment configured for the
target. The target and source parameters are the lists of targets
and sources for the configured action.

The returned key should typically be a tuple of values derived from
the arguments, using any appropriate logic to decide how multiple
invocations should be batched. For example, a batch_key function
may decide to return the value of a specific construction variable
from env which will cause scons to batch-build targets with
matching values of that construction variable, or perhaps return
the Python id() of the entire construction environment, in which
case scons will batch-build all targets configured with the same
construction environment. Returning None indicates that the
particular target should not be part of any batched build, but
instead will be built by a separate invocation of action's command
or function. Example:

def batch_key(action, env, target, source):
tdir = target[0].dir
if tdir.name == 'special':
# Don't batch-build any target
# in the special/ subdirectory.
return None
return (id(action), id(env), tdir)
a = Action('build $CHANGED_SOURCES', batch_key=batch_key)

Miscellaneous Action Functions
SCons supplies Action functions that arrange for various common
file and directory manipulations to be performed. These are similar
in concept to "tasks" in the Ant build tool, although the
implementation is slightly different. These functions do not
actually perform the specified action at the time the function is
called, but rather are factory functions which return an Action
object that can be executed at the appropriate time.

There are two natural ways that these Action Functions are intended
to be used.

First, if you need to perform the action at the time the SConscript
file is being read, you can use the Execute global function:

Execute(Touch('file'))

Second, you can use these functions to supply Actions in a list for
use by the env.Command method. This can allow you to perform more
complicated sequences of file manipulation without relying on
platform-specific external commands:

env = Environment(TMPBUILD='/tmp/builddir')
env.Command(
target='foo.out',
source='foo.in',
action=[
Mkdir('$TMPBUILD'),
Copy('$TMPBUILD', '${SOURCE.dir}'),
"cd $TMPBUILD && make",
Delete('$TMPBUILD'),
],
)

Chmod(dest, mode)
Returns an Action object that changes the permissions on the
specified dest file or directory to the specified mode which
can be octal or string, similar to the bash command. Examples:

Execute(Chmod('file', 0o755))

env.Command('foo.out', 'foo.in',
[Copy('$TARGET', '$SOURCE'),
Chmod('$TARGET', 0o755)])

Execute(Chmod('file', "ugo+w"))

env.Command('foo.out', 'foo.in',
[Copy('$TARGET', '$SOURCE'),
Chmod('$TARGET', "ugo+w")])

The behavior of Chmod is limited on Windows, see the notes in
the Python documentation for os.chmod, which is the underlying
function.

Copy(dest, src)
Returns an Action object that will copy the src source file or
directory to the dest destination file or directory. Examples:

Execute(Copy('foo.output', 'foo.input'))

env.Command('bar.out', 'bar.in', Copy('$TARGET', '$SOURCE'))

Delete(entry, [must_exist])
Returns an Action that deletes the specified entry, which may
be a file or a directory tree. If a directory is specified, the
entire directory tree will be removed. If the must_exist flag
is set to a true value, then a Python error will be raised if
the specified entry does not exist; the default is false, that
is, the Action will silently do nothing if the entry does not
exist. Examples:

Execute(Delete('/tmp/buildroot'))

env.Command(
'foo.out',
'foo.in',
action=[
Delete('${TARGET.dir}'),
MyBuildAction,
],
)

Execute(Delete('file_that_must_exist', must_exist=True))

Mkdir(name)
Returns an Action that creates the directory name and all
needed intermediate directories. name may also be a list of
directories to create. Examples:

Execute(Mkdir('/tmp/outputdir'))

env.Command(
'foo.out',
'foo.in',
action=[
Mkdir('/tmp/builddir'),
Copy('/tmp/builddir/foo.in', '$SOURCE'),
"cd /tmp/builddir && make",
Copy('$TARGET', '/tmp/builddir/foo.out'),
],
)

Move(dest, src)
Returns an Action that moves the specified src file or
directory to the specified dest file or directory. Examples:

Execute(Move('file.destination', 'file.source'))

env.Command(
'output_file',
'input_file',
action=[MyBuildAction, Move('$TARGET', 'file_created_by_MyBuildAction')],
)

Touch(file)
Returns an Action that updates the modification time on the
specified file. Examples:

Execute(Touch('file_to_be_touched'))

env.Command('marker', 'input_file', action=[MyBuildAction, Touch('$TARGET')])

Variable Substitution
Before executing a command, scons performs parameter expansion
(substitution) on the string that makes up the action part of the
builder. The format of a substitutable parameter is ${expression}.
If expression refers to a variable, the braces in ${expression} can
be omitted unless the variable name is immediately followed by a
character that could either be interpreted as part of the name, or
is Python syntax such as [ (for indexing/slicing) or . (for
attribute access - see Special Attributes below).

If expression refers to a construction variable, it is replaced
with the value of that variable in the construction environment at
the time of execution. If expression looks like a variable name but
is not defined in the construction environment it is replaced with
an empty string. If expression refers to one of the Special
Variables (see below) the corresponding value of the variable is
substituted. expression may also be a Python expression to be
evaluated. See Python Code Substitution below for a description.

SCons uses the following rules when converting construction
variables into command line strings:

• If the value is a string it is interpreted as space delimited
command line arguments.

• If the value is a list it is interpreted as a list of command
line arguments. Each element of the list is converted to a
string.

• Anything that is not a list or string is converted to a string
and interpreted as a single command line argument.

• Newline characters (\n) delimit lines. The newline parsing is
done after all other parsing, so it is not possible for
arguments (e.g. file names) to contain embedded newline
characters.

• For a literal $ use $$. For example, $$FOO will be left in the
final string as $FOO.

When a build action is executed, a hash of the command line is
saved, together with other information about the target(s) built by
the action, for future use in rebuild determination. This is called
the build signature (or build action signature). The escape
sequence $( subexpression $) may be used to indicate parts of a
command line that may change without causing a rebuild--that is,
which are not to be included when calculating the build signature.
All text from $( up to and including the matching $) will be
removed from the command line before it is added to the build
signature while only the $( and $) will be removed before the
command is executed. For example, the command line string:

"echo Last build occurred $( $TODAY $). > $TARGET"

would execute the command:

echo Last build occurred $TODAY. > $TARGET

but the build signature added to any target files would be computed
from:

echo Last build occurred . > $TARGET

While construction variables are normally directly substituted, if
a construction variable has a value which is a callable Python
object (a function, or a class with a __call__ method), that object
is called during substitution. The callable must accept four
arguments: target, source, env and for_signature. source is a list
of source nodes, target is a list of target nodes, env is the
construction environment to use for context, and for_signature is a
boolean value that tells the callable if it is being called for the
purpose of generating a build signature. Since the build signature
is used for rebuild determination, variable elements that do not
affect whether a rebuild should be triggered should be omitted from
the returned string if for_signature is true. See $( and $) above
for the syntax.

SCons will insert whatever the callable returns into the expanded
string:

def foo(target, source, env, for_signature):
return "bar"

# Will expand $BAR to "bar baz"
env = Environment(FOO=foo, BAR="$FOO baz")

As a reminder, substitution happens when $BAR is actually used in a
builder action. The value of env['BAR'] will be exactly as it was
set: "$FOO baz". This can make debugging tricky, as the substituted
result is not available at the time the SConscript files are being
interpreted and thus not available to print(). However, you can
perform the substitution on demand by calling the env.subst method
for this purpose.

You can use this feature to pass arguments to a callable variable
by creating a callable class that stores passed arguments in the
instance, and then uses them (in the __call__ method) when the
instance is called. Note that in this case, the entire variable
expansion must be enclosed by curly braces so that the arguments
will be associated with the instantiation of the class:

class foo:
def __init__(self, arg):
self.arg = arg

def __call__(self, target, source, env, for_signature):
return self.arg + " bar"

# Will expand $BAR to "my argument bar baz"
env=Environment(FOO=foo, BAR="${FOO('my argument')} baz")

Substitution: Special Variables
Besides regular construction variables, scons provides the
following Special Variables for use in expanding commands:

$CHANGED_SOURCES
The file names of all sources of the build command that have
changed since the target was last built.

$CHANGED_TARGETS
The file names of all targets that would be built from sources
that have changed since the target was last built.

$SOURCE
The file name of the source of the build command, or the file
name of the first source if multiple sources are being built.

$SOURCES
The file names of the sources of the build command.

$TARGET
The file name of the target being built, or the file name of
the first target if multiple targets are being built.

$TARGETS
The file names of all targets being built.

$UNCHANGED_SOURCES
The file names of all sources of the build command that have
not changed since the target was last built.

$UNCHANGED_TARGETS
The file names of all targets that would be built from sources
that have not changed since the target was last built.

These names are reserved and may not be assigned to or used as
construction variables. SCons computes them in a context-dependent
manner and they and are not retrieved from a construction
environment.

For example, the following builder call:

env = Environment(CC='cc')
env.Command(
target=['foo'],
source=['foo.c', 'bar.c'],
action='@echo $CC -c -o $TARGET $SOURCES'
)

would produce the following output:

cc -c -o foo foo.c bar.c

In the previous example, a string ${SOURCES[1]} would expand to:
bar.c.

Substitution: Special Attributes
A variable name may have the following modifiers appended within
the enclosing curly braces to access properties of the interpolated
string. These are known as special attributes.
base -
The base path of the file name,
including the directory path
but excluding any suffix.

dir - The name of the directory in which the file exists.
file - The file name, minus any directory portion.
filebase - Like file but minus its suffix.
suffix - Just the file suffix.
abspath - The absolute path name of the file.
relpath - The path name of the file relative to the root
SConstruct file's directory.
posix -
The path with directories separated by forward slashes
(/).
Sometimes necessary on Windows systems
when a path references a file on other (POSIX) systems.

windows -
The path with directories separated by backslashes
(\\).
Sometimes necessary on POSIX-style systems
when a path references a file on other (Windows) systems.
win32 is a (deprecated) synonym for
windows.

srcpath -
The directory and file name to the source file linked to
this file through
VariantDir().
If this file isn't linked,
it just returns the directory and filename unchanged.

srcdir -
The directory containing the source file linked to this
file through
VariantDir().
If this file isn't linked,
it just returns the directory part of the filename.

rsrcpath -
The directory and file name to the source file linked to
this file through
VariantDir().
If the file does not exist locally but exists in a
Repository,
the path in the Repository is returned.
If this file isn't linked, it just returns the
directory and filename unchanged.

rsrcdir -
The Repository directory containing the source file linked
to this file through
VariantDir().
If this file isn't linked,
it just returns the directory part of the filename.

For example, the specified target will expand as follows for the
corresponding modifiers:

$TARGET => sub/dir/file.x
${TARGET.base} => sub/dir/file
${TARGET.dir} => sub/dir
${TARGET.file} => file.x
${TARGET.filebase} => file
${TARGET.suffix} => .x
${TARGET.abspath} => /top/dir/sub/dir/file.x
${TARGET.relpath} => sub/dir/file.x

$TARGET => ../dir2/file.x
${TARGET.abspath} => /top/dir2/file.x
${TARGET.relpath} => ../dir2/file.x

SConscript('src/SConscript', variant_dir='sub/dir')
$SOURCE => sub/dir/file.x
${SOURCE.srcpath} => src/file.x
${SOURCE.srcdir} => src

Repository('/usr/repository')
$SOURCE => sub/dir/file.x
${SOURCE.rsrcpath} => /usr/repository/src/file.x
${SOURCE.rsrcdir} => /usr/repository/src

Some modifiers can be combined, like ${TARGET.srcpath.base),
${TARGET.file.suffix}, etc.

Python Code Substitution
If a substitutable expression using the notation ${expression} does
not appear to match one of the other substitution patterns, it is
evaluated as a Python expression. This uses Python's eval function,
with the globals parameter set to the current environment's set of
construction variables, and the result substituted in. So in the
following case:

env.Command(
'foo.out', 'foo.in', "echo ${COND==1 and 'FOO' or 'BAR'} > $TARGET"
)

the command executed will be either

echo FOO > foo.out

echo BAR > foo.out

according to the current value of env['COND'] when the command is
executed. The evaluation takes place when the target is being
built, not when the SConscript is being read. So if env['COND'] is
changed later in the SConscript, the final value will be used.

Here's a more complete example. Note that all of COND, FOO, and BAR
are construction variables, and their values are substituted into
the final command. FOO is a list, so its elements are interpolated
separated by spaces.

env=Environment()
env['COND'] = 1
env['FOO'] = ['foo1', 'foo2']
env['BAR'] = 'barbar'
env.Command(
'foo.out', 'foo.in', "echo ${COND==1 and FOO or BAR} > $TARGET"
)

will execute:

echo foo1 foo2 > foo.out

In point of fact, Python expression evaluation is how the special
attributes are substituted: they are simply attributes of the
Python objects that represent $TARGET, $SOURCES, etc., which SCons
passes to eval which returns the value.

Note
Use of the Python eval function is considered to have security
implications, since, depending on input sources, arbitrary
unchecked strings of code can be executed by the Python
interpreter. Although SCons makes use of it in a somewhat
restricted context, you should be aware of this issue when
using the ${python-expression-for-subst} form.

Scanner Objects
Scanner objects are used to scan specific file types for implicit
dependencies, for example embedded preprocessor/compiler directives
that cause other files to be included during processing. SCons has a
number of pre-built Scanner objects, so it is usually only necessary to
set up Scanners for new file types. You do this by calling the Scanner
factory function. Scanner accepts the following arguments. Only
function is required; the rest are optional:

function
A scanner function to call to process a given Node (usually a file)
and return a list of Nodes representing the implicit dependencies
(usually files) found in the contents. The function must accept
three required arguments, node, env and path, and an optional
fourth, arg. node is the internal SCons node representing the file
to scan, env is the construction environment to use during the
scan, and path is a tuple of directories that can be searched for
files, as generated by the optional scanner path_function (see
below). If argument was supplied when the Scanner object was
created, it is given as arg when the scanner function is called;
since argument is optional, the default is no arg.

The function can use use str(node) to fetch the name of the file,
node.dir to fetch the directory the file is in, node.get_contents()
to fetch the contents of the file as bytes or
node.get_text_contents() to fetch the contents of the file as text.

The function must take into account the path directories when
generating the dependency Nodes. To illustrate this, a C language
source file may contain a line like #include "foo.h". However,
there is no guarantee that foo.h exists in the current directory:
the contents of $CPPPATH is passed to the C preprocessor which will
look in those places for the header, so the scanner function needs
to look in those places as well in order to build Nodes with
correct paths. Using FindPathDirs with an argument of CPPPATH as
the path_function in the Scanner call means the scanner function
will be called with the paths extracted from $CPPPATH in the
environment env passed as the paths parameter.

Note that the file to scan is not guaranteed to exist at the time
the scanner is called - it could be a generated file which has not
been generated yet - so the scanner function must be tolerant of
that.

Alternatively, you can supply a dictionary as the function
parameter, to map keys (such as file suffixes) to other Scanner
objects. A Scanner created this way serves as a dispatcher: the
Scanner's skeys parameter is automatically populated with the
dictionary's keys, indicating that the Scanner handles Nodes which
would be selected by those keys; the mapping is then used to pass
the file on to a different Scanner that would not have been
selected to handle that Node based on its own skeys.

name
The name to use for the Scanner. This is mainly used to identify
the Scanner internally. The default value is "NONE".

argument
If specified, will be passed to the scanner function function and
the path function path_function when called, as the optional
parameter each of those functions takes.

skeys
Scanner key(s) indicating the file types this scanner is associated
with. Used internally to select an appropriate scanner. In the
usual case of scanning for file names, this argument will be a list
of suffixes for the different file types that this Scanner knows
how to scan. If skeys is a string, it will be expanded into a list
by the current environment.

path_function
A Python function that takes four or five arguments: a construction
environment, a Node for the directory containing the SConscript
file in which the first target was defined, a list of target nodes,
a list of source nodes, and the value of argument if it was
supplied when the Scanner was created. Must return a tuple of
directories that can be searched for files to be returned by this
Scanner object. (Note that the FindPathDirs function can be used to
return a ready-made path_function for a given construction variable
name, instead of having to write your own function from scratch.)

node_class
The class of Node that should be returned by this Scanner object.
Any strings or other objects returned by the scanner function that
are not of this class will be run through the function supplied by
the node_factory argument. A value of None can be supplied to
indicate no conversion; the default is to return File nodes.

node_factory
A Python function that will take a string or other object and turn
it into the appropriate class of Node to be returned by this
Scanner object, as indicated by node_class.

scan_check
A Python function that takes two arguments, a Node (file) and a
construction environment, and returns whether the Node should, in
fact, be scanned for dependencies. This check can be used to
eliminate unnecessary calls to the scanner function when, for
example, the underlying file represented by a Node does not yet
exist.

recursive
Specifies whether this scanner should be re-invoked on the
dependency files returned by the scanner. If omitted, the Node
subsystem will only invoke the scanner on the file being scanned
and not recurse. Recursion is needed when the files returned by the
scanner may themselves contain further file dependencies, as in the
case of preprocessor #include lines. A value that evaluates true
enables recursion; recursive may be a callable function, in which
case it will be called with a list of Nodes found and should return
a list of Nodes that should be scanned recursively; this can be
used to select a specific subset of Nodes for additional scanning.

Once created, a Scanner can added to an environment by setting it in
the $SCANNERS list, which automatically triggers SCons to also add it
to the environment as a method. However, usually a scanner is not truly
standalone, but needs to be plugged in to the existing selection
mechanism for deciding how to scan source files based on filename
extensions. For this, SCons has a global SourceFileScanner object that
is used by the Object, SharedObject and StaticObject builders to decide
which scanner should be used. You can use the
SourceFileScanner.add_scanner() method to add your own Scanner object
to the SCons infrastructure that builds target programs or libraries
from a list of source files of different types:

def xyz_scan(node, env, path):
contents = node.get_text_contents()
# Scan the contents and return the included files.

XYZScanner = Scanner(xyz_scan)

SourceFileScanner.add_scanner('.xyz', XYZScanner)

env.Program('my_prog', ['file1.c', 'file2.f', 'file3.xyz'])

Tool Modules
Additional tools can be added to a project either by placing them in a
site_tools subdirectory of a site directory, or in a custom location
specified to scons by giving the toolpath keyword argument to
Environment. A tool module is a form of Python module, invoked
internally using the Python import mechanism, so a tool can consist
either of a single source file taking the name of the tool (e.g.
mytool.py) or a directory taking the name of the tool (e.g. mytool/)
which contains at least an __init__.py file.

The toolpath parameter takes a list as its value:

env = Environment(tools=['default', 'foo'], toolpath=['tools'])

This looks for a tool specification module (mytool.py, or directory
mytool) in directory tools and in the standard locations, as well as
using the ordinary default tools for the platform.

Directories specified via toolpath are prepended to the existing tool
path. The default tool path is any site_tools directories, so tools in
a specified toolpath take priority, followed by tools in a site_tools
directory, followed by built-in tools. For example, adding a tool
specification module gcc.py to the toolpath directory would override
the built-in gcc tool. The tool path is stored in the environment and
will be used by subsequent calls to the Tool method, as well as by
env.Clone.

base = Environment(toolpath=['custom_path'])
derived = base.Clone(tools=['custom_tool'])
derived.CustomBuilder()

A tool specification module must include two functions:

generate(env, **kwargs)
Modify the construction environment env to set up necessary
construction variables, Builders, Emitters, etc., so the facilities
represented by the tool can be executed. Care should be taken not
to overwrite construction variables intended to be settable by the
user. For example:

def generate(env):
...
if 'MYTOOL' not in env:
env['MYTOOL'] = env.Detect("mytool")
if 'MYTOOLFLAGS' not in env:
env['MYTOOLFLAGS'] = SCons.Util.CLVar('--myarg')
...

The generate function may use any keyword arguments that the user
supplies via kwargs to vary its initialization.

exists(env)
Return a true value if the tool can be called in the context of
env. else false. Usually this means looking up one or more known
programs using the PATH from the supplied env, but the tool can
make the exists decision in any way it chooses.

Note
At the moment, user-added tools do not automatically have their
exists function called. As a result, it is recommended that the
generate function be defensively coded - that is, do not rely on
any necessary existence checks already having been performed. This
is expected to be a temporary limitation, and the exists function
should still be provided.

The elements of the tools list may also be functions or callable
objects, in which case the Environment method will call those objects
to update the new construction environment (see Tool for more details):

def my_tool(env):
env['XYZZY'] = 'xyzzy'

env = Environment(tools=[my_tool])

The individual elements of the tools list may also themselves be lists
or tuples of the form (toolname, kw_dict). SCons searches for the
toolname specification file as described above, and passes kw_dict,
which must be a dictionary, as keyword arguments to the tool's generate
function. The generate function can use the arguments to modify the
tool's behavior by setting up the environment in different ways or
otherwise changing its initialization.

# in tools/my_tool.py:
def generate(env, **kwargs):
# Sets MY_TOOL to the value of keyword 'arg1' '1' if not supplied
env['MY_TOOL'] = kwargs.get('arg1', '1')

def exists(env):
return True

# in SConstruct:
env = Environment(tools=['default', ('my_tool', {'arg1': 'abc'})],
toolpath=['tools'])

The tool specification (my_tool in the example) can use the $PLATFORM
variable from the construction environment it is passed to customize
the tool for different platforms.

Tools can be "nested" - that is, they can be located within a
subdirectory in the toolpath. A nested tool name uses a dot to
represent a directory separator

# namespaced builder
env = Environment(ENV=os.environ.copy(), tools=['SubDir1.SubDir2.SomeTool'])
env.SomeTool(targets, sources)

# Search Paths
# SCons\Tool\SubDir1\SubDir2\SomeTool.py
# SCons\Tool\SubDir1\SubDir2\SomeTool\__init__.py
# .\site_scons\site_tools\SubDir1\SubDir2\SomeTool.py
# .\site_scons\site_tools\SubDir1\SubDir2\SomeTool\__init__.py

SYSTEM-SPECIFIC BEHAVIOR
scons and its configuration files are very portable, due largely to its
implementation in Python. There are, however, a few portability issues
waiting to trap the unwary.

.C File Suffix
scons handles the upper-case .C file suffix differently, depending on
the capabilities of the underlying system. On a case-sensitive system
such as Linux or UNIX, scons treats a file with a .C suffix as a C++
source file. On a case-insensitive system such as Windows, scons treats
a file with a .C suffix as a C source file.

Fortran File Suffixes
There are several ways source file suffixes impact the behavior of
SCons when working with Fortran language code (not all are
system-specific, but they are included here for completeness).

As the Fortran language has evolved through multiple standards
editions, projects might have a need to handle files from different
language generations differently. To this end, SCons dispatches to a
different compiler dialect setup (expressed as a set of construction
variables) depending on the file suffix. By default, all of these
setups start out the same, but individual construction variables can be
modified as needed to tune a given dialect. Each of these dialacts has
a tool specification module whose documentation describes the
construction variables associated with that dialect: .f (as well as
.for and .ftn) in fortran; (construction variables start with FORTRAN)
.f77 in f77; (construction variables start with F77) .f90 in f90;
(construction variables start with F90) .f95 in f95; (construction
variables start with F95) .f03 in f03; (construction variables start
with F03) .f08 in f08 (construction variables start with F08).

While SCons recognizes multiple internal dialects based on filename
suffixes, the convention of various available Fortran compilers is to
assign an actual meaning to only two of these suffixes: .f (as well as
.for and .ftn) refers to the fixed-format source code that was the only
available option in FORTRAN 77 and earlier, and .f90 refers to
free-format source code which became available as of the Fortran 90
standard. Some compilers recognize suffixes which correspond to Fortran
specifications later then F90 as equivalent to .f90 for this purpose,
while some do not - check the documentation for your compiler. An
occasionally suggested policy suggestion is to use only .f and .f90 as
Fortran filename suffixes. The fixed/free form determination can
usually be controlled explicitly with compiler flags (e.g.
-ffixed-form for gfortran), overriding any assumption that may be made
based on the source file suffix.

The source file suffix does not imply conformance with the
similarly-named Fortran standard - a suffix of .f08 does not mean you
are compiling specifically for Fortran 2008. Normally, compilers
provide command-line options for making this selection (e.g.
-std=f2008 for gfortran).

For dialects from F90 on (including the generic FORTRAN dialect), a
suffix of .mod is recognized for Fortran modules. These files are a
side effect of compiling a Fortran source file containing module
declarations, and must be available when other code which declares that
it uses the module is processed. SCons does not currently have
integrated support for submodules, introduced in the Fortran 2008
standard - the invoked compiler will produce results, but SCons will
not recognize .smod files as tracked objects.

On a case-sensitive system such as Linux or UNIX, a file with a an
upper-cased suffix from the set .F, .FOR, .FTN, .F90, .F95, .F03 and
.F08 is treated as a Fortran source file which shall first be run
through the standard C preprocessor. The lower-cased versions of these
suffixes do not trigger this behavior. On systems which do not
distinguish between uppper and lower case in filenames, this behavior
is not available, but files suffixed with either .FPP or .fpp are
always passed to the preprocessor first. This matches the convention of
gfortran from the GNU Compiler Collection, and also followed by certain
other Fortran compilers. For these two suffixes, the generic FORTRAN
dialect will be selected.

SCons itself does not invoke the preprocessor, that is handled by the
compiler, but it adds construction variables which are applicable to
the preprocessor run. You can see this difference by examining
$FORTRANPPCOM and $FORTRANPPCOMSTR which are used instead of
$FORTRANCOM and $FORTRANCOMSTR for that dialect.

Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons
Cygwin supplies a set of tools and utilities that let users work on a
Windows system using a POSIX-like environment. The Cygwin tools,
including Cygwin Python, do this, in part, by sharing an ability to
interpret POSIX-style path names. For example, the Cygwin tools will
internally translate a Cygwin path name like /cygdrive/c/mydir to an
equivalent Windows pathname of C:/mydir (equivalent to C:\mydir).

Versions of Python that are built for native Windows execution, such as
the python.org and ActiveState versions, do not understand the Cygwin
path name semantics. This means that using a native Windows version of
Python to build compiled programs using Cygwin tools (such as gcc,
bison and flex) may yield unpredictable results. "Mixing and matching"
in this way can be made to work, but it requires careful attention to
the use of path names in your SConscript files.

In practice, users can sidestep the issue by adopting the following
guidelines: When using Cygwin's gcc for compiling, use the
Cygwin-supplied Python interpreter to run scons; when using Microsoft
Visual C/C++ (or some other "native" Windows compiler) use the
python.org, Microsoft Store, ActiveState or other native version of
Python to run scons.

This discussion largely applies to the msys2 environment as well (with
the use of the mingw compiler toolchain), in particular the
recommendation to use the msys2 version of Python if running scons from
inside an msys2 shell.

Windows: scons.bat file
On Windows, if scons is executed via a wrapper scons.bat batch file,
there are (at least) two ramifications. Note this is no longer the
default - scons installed via Python''s pip installer will have an
scons.exe which does not have these limitations:

First, Windows command-line users that want to use variable assignment
on the command line may have to put double quotes around the
assignments, otherwise the Windows command shell will consume those as
arguments to itself, not to scons:

scons "FOO=BAR" "BAZ=BLEH"

Second, the Cygwin shell does not recognize typing scons at the command
line prompt as referring to this wrapper. You can work around this
either by executing scons.bat (including the extension) from the Cygwin
command line, or by creating a wrapper shell script named scons which
invokes scons.bat.

MinGW
The MinGW bin directory must be in your PATH environment variable or
the ['ENV']['PATH'] construction variable for scons to detect and use
the MinGW tools. When running under the native Windows Python;
interpreter, scons will prefer the MinGW tools over the Cygwin tools,
if they are both installed, regardless of the order of the bin
directories in the PATH variable. If you have both MSVC and MinGW
installed and you want to use MinGW instead of MSVC, then you must
explicitly tell scons to use MinGW by passing tools=['mingw'] to the
Environment function, because scons will prefer the MSVC tools over the
MinGW tools.

ENVIRONMENT
In general, scons is not controlled by environment variables set in the
shell used to invoke it, leaving it up to the SConscript file author to
import those if desired. However the following variables are imported
by scons itself if set:

SCONS_LIB_DIR
Specifies the directory that contains the scons Python module
directory. Normally scons can deduce this, but in some
circumstances, such as working with a source release, it may be
necessary to specify (for example,
/home/aroach/scons-src-0.01/src/engine).

SCONSFLAGS
A string containing options that will be used by scons in addition
to those passed on the command line. Can be used to reduce frequent
retyping of common options. The contents of SCONSFLAGS are
considered before any passed command line options, so the command
line can be used to override SCONSFLAGS options if necessary.

SCONS_CACHE_MSVC_CONFIG
(Windows only). If set, save the shell environment variables
generated when setting up the Microsoft Visual C++ compiler (and/or
Build Tools) to a cache file, to give these settings, which are
relatively expensive to generate, persistence across scons
invocations. Use of this option is primarily intended to aid
performance in tightly controlled Continuous Integration setups.

If set to a True-like value ("1", "true" or "True") will cache to a
file named .scons_msvc_cache.json in the user's home directory. If
set to a pathname, will use that pathname for the cache.

Note: use this cache with caution as it might be somewhat fragile:
while each major toolset version (e.g. Visual Studio 2017 vs 2019)
and architecture pair will get separate cache entries, if toolset
updates cause a change to settings within a given release series,
scons will not detect the change and will reuse old settings.
Remove the cache file in case of problems with this. scons will
ignore failures reading or writing the file and will silently
revert to non-cached behavior in such cases.

Available since scons 3.1 (experimental).

QTDIR
If using the qt tool, this is the path to the Qt installation to
build against. SCons respects this setting because it is a
long-standing convention in the Qt world, where multiple Qt
installations are possible.

SEE ALSO
The SCons User Guide at
https://scons.org/doc/production/HTML/scons-user.html

The SCons Design Document (old)

The SCons Cookbook at
https://scons-cookbook.readthedocs.io
for examples of how to solve various problems with SCons.

SCons source code
on GitHub[6]

The SCons API Reference
https://scons.org/doc/production/HTML/scons-api/index.html
(for internal details)

AUTHORS
Originally: Steven Knight knight@baldmt.com and Anthony Roach
aroach@electriceyeball.com.

Since 2010: The SCons Development Team scons-dev@scons.org.

AUTHOR
The SCons Development Team

NOTES
1. https://github.com/SCons/scons-contrib
https://github.com/SCons/scons-contrib

2. LLVM specification
https://clang.llvm.org/docs/JSONCompilationDatabase.html

3. JEP 313
https:openjdk.java.net/jeps/313

4. If no_progress is set via SetOption in an SConscript file (but not
if set in a site_init.py file) there will still be an initial
status message about reading SConscript files since SCons has to
start reading them before it can see the SetOption.

5. http://www.opensource.org/licenses/alphabetical
http://www.opensource.org/licenses/alphabetical

6. on GitHub
https://github.com/SCons/scons

SCons __VE<pubdate>Released.Sun, 18 Jul 2021 17:34:05 -0700</pubdate> SCONS(1)

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