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man-pages(7)           Miscellaneous Information Manual           man-pages(7)

NAME
       man-pages - conventions for writing Linux man pages

SYNOPSIS
       man [section] title

DESCRIPTION
       This  page describes the conventions that should be employed when writ-
       ing man pages for the Linux  man-pages  project,  which  documents  the
       user-space API provided by the Linux kernel and the GNU C library.  The
       project thus provides most of the pages in Section 2, many of the pages
       that appear in Sections 3, 4, and 7, and a few of the pages that appear
       in Sections 1, 5, and 8 of the man pages on a Linux system.   The  con-
       ventions  described on this page may also be useful for authors writing
       man pages for other projects.

   Sections of the manual pages
       The manual Sections are traditionally defined as follows:

       1 User commands (Programs)
              Commands that can be executed by the user from within a shell.

       2 System calls
              Functions which wrap operations performed by the kernel.

       3 Library calls
              All library functions excluding the system call  wrappers  (Most
              of the libc functions).

       4 Special files (devices)
              Files found in /dev which allow to access to devices through the
              kernel.

       5 File formats and configuration files
              Describes various human-readable file formats and  configuration
              files.

       6 Games
              Games and funny little programs available on the system.

       7 Overview, conventions, and miscellaneous
              Overviews  or  descriptions  of various topics, conventions, and
              protocols, character set standards, the standard filesystem lay-
              out, and miscellaneous other things.

       8 System management commands
              Commands like mount(8), many of which only root can execute.

   Macro package
       New  manual  pages  should be marked up using the groff an.tmac package
       described in man(7).  This choice is mainly for consistency:  the  vast
       majority  of  existing  Linux  manual  pages  are marked up using these
       macros.

   Conventions for source file layout
       Please limit source code line length to no more than about  75  charac-
       ters  wherever  possible.   This helps avoid line-wrapping in some mail
       clients when patches are submitted inline.

   Title line
       The first command in a man page should be a TH command:

              .TH title section date source manual-section

       The arguments of the command are as follows:

       title  The title of the man page,  written  in  all  caps  (e.g.,  MAN-
              PAGES).

       section
              The section number in which the man page should be placed (e.g.,
              7).

       date   The date of the last nontrivial change that was made to the  man
              page.   (Within  the man-pages project, the necessary updates to
              these timestamps are handled automatically by scripts, so  there
              is  no  need to manually update them as part of a patch.)  Dates
              should be written in the form YYYY-MM-DD.

       source The name and version of the project  that  provides  the  manual
              page  (not necessarily the package that provides the functional-
              ity).

       manual-section
              Normally, this should be empty, since the default value will  be
              good.

   Sections within a manual page
       The  list  below shows conventional or suggested sections.  Most manual
       pages should include at least the highlighted sections.  Arrange a  new
       manual page so that sections are placed in the order shown in the list.

              NAME
              LIBRARY          [Normally only in Sections 2, 3]
              SYNOPSIS
              CONFIGURATION    [Normally only in Section 4]
              DESCRIPTION
              OPTIONS          [Normally only in Sections 1, 8]
              EXIT STATUS      [Normally only in Sections 1, 8]
              RETURN VALUE     [Normally only in Sections 2, 3]
              ERRORS           [Typically only in Sections 2, 3]
              ENVIRONMENT
              FILES
              VERSIONS         [Normally only in Sections 2, 3]
              ATTRIBUTES       [Normally only in Sections 2, 3]
              STANDARDS
              NOTES
              CAVEATS
              BUGS
              EXAMPLES
              AUTHORS          [Discouraged]
              REPORTING BUGS   [Not used in man-pages]
              COPYRIGHT        [Not used in man-pages]
              SEE ALSO

       Where  a  traditional  heading would apply, please use it; this kind of
       consistency can make the information  easier  to  understand.   If  you
       must,  you  can  create your own headings if they make things easier to
       understand (this can be especially useful for pages in Sections  4  and
       5).   However,  before  doing  this, consider whether you could use the
       traditional headings, with some subsections  (.SS)  within  those  sec-
       tions.

       The following list elaborates on the contents of each of the above sec-
       tions.

       NAME   The name of this manual page.

              See man(7) for important details of the line(s) that should fol-
              low the .SH NAME command.  All words in this line (including the
              word immediately following the "\-") should be in lowercase, ex-
              cept  where  English or technical terminological convention dic-
              tates otherwise.

       LIBRARY
              The library providing a symbol.

              It shows the common name of the library, and in parentheses, the
              name  of the library file and, if needed, the linker flag needed
              to link a program against it: (libfoo[, -lfoo]).

       SYNOPSIS
              A brief summary of the command or function's interface.

              For commands, this shows the syntax of the command and its argu-
              ments  (including  options); boldface is used for as-is text and
              italics are used to indicate  replaceable  arguments.   Brackets
              ([])  surround  optional  arguments,  vertical bars (|) separate
              choices, and ellipses (...) can be repeated.  For functions,  it
              shows  any  required  data  declarations or #include directives,
              followed by the function declaration.

              Where a feature test macro must be defined in  order  to  obtain
              the  declaration  of  a  function  (or a variable) from a header
              file, then the SYNOPSIS should indicate this,  as  described  in
              feature_test_macros(7).

       CONFIGURATION
              Configuration details for a device.

              This section normally appears only in Section 4 pages.

       DESCRIPTION
              An explanation of what the program, function, or format does.

              Discuss how it interacts with files and standard input, and what
              it produces on standard output or standard error.   Omit  inter-
              nals  and implementation details unless they're critical for un-
              derstanding the interface.  Describe the usual case; for  infor-
              mation on command-line options of a program use the OPTIONS sec-
              tion.

              When describing new behavior or new flags for a system  call  or
              library  function,  be  careful  to note the kernel or C library
              version that introduced the change.   The  preferred  method  of
              noting  this  information for flags is as part of a .TP list, in
              the following form (here, for a new system call flag):

                       XYZ_FLAG (since Linux 3.7)
                              Description of flag...

              Including version information is especially useful to users  who
              are  constrained  to  using  older  kernel or C library versions
              (which is typical in embedded systems, for example).

       OPTIONS
              A description of the command-line options accepted by a  program
              and how they change its behavior.

              This  section  should  appear  only  for  Section 1 and 8 manual
              pages.

       EXIT STATUS
              A list of the possible exit status values of a program  and  the
              conditions that cause these values to be returned.

              This  section  should  appear  only  for  Section 1 and 8 manual
              pages.

       RETURN VALUE
              For Section 2 and 3 pages, this section gives a list of the val-
              ues the library routine will return to the caller and the condi-
              tions that cause these values to be returned.

       ERRORS For Section 2 and 3 manual pages, this is a list of  the  values
              that may be placed in errno in the event of an error, along with
              information about the cause of the errors.

              Where several different conditions produce the same  error,  the
              preferred  approach is to create separate list entries (with du-
              plicate error names) for each of the conditions.  This makes the
              separate conditions clear, may make the list easier to read, and
              allows metainformation (e.g., kernel version  number  where  the
              condition  first became applicable) to be more easily marked for
              each condition.

              The error list should be in alphabetical order.

       ENVIRONMENT
              A list of all environment variables that affect the  program  or
              function and how they affect it.

       FILES  A  list  of the files the program or function uses, such as con-
              figuration files, startup files, and files the program  directly
              operates on.

              Give  the full pathname of these files, and use the installation
              process to modify the directory part to match user  preferences.
              For  many  programs,  the  default  installation  location is in
              /usr/local, so your base manual page should  use  /usr/local  as
              the base.

       ATTRIBUTES
              A summary of various attributes of the function(s) documented on
              this page.  See attributes(7) for further details.

       VERSIONS
              A brief summary of the Linux kernel or glibc  versions  where  a
              system  call  or  library function appeared, or changed signifi-
              cantly in its operation.

              As a general rule, every new interface should include a VERSIONS
              section in its manual page.  Unfortunately, many existing manual
              pages don't include this information (since there was no  policy
              to  do  so  when they were written).  Patches to remedy this are
              welcome, but, from the perspective of  programmers  writing  new
              code, this information probably matters only in the case of ker-
              nel interfaces that have been added in Linux 2.4 or later (i.e.,
              changes  since  Linux 2.2), and library functions that have been
              added to glibc since glibc 2.1 (i.e., changes since glibc 2.0).

              The syscalls(2) manual page also provides information about ker-
              nel versions in which various system calls first appeared.

       STANDARDS
              A description of any standards or conventions that relate to the
              function or command described by the manual page.

              The preferred terms to use for the various standards are  listed
              as headings in standards(7).

              For  a  page  in  Section  2  or 3, this section should note the
              POSIX.1 version(s) that the call conforms to, and  also  whether
              the call is specified in C99.  (Don't worry too much about other
              standards like SUS, SUSv2, and XPG, or the SVr4 and  4.xBSD  im-
              plementation  standards,  unless the call was specified in those
              standards, but isn't in the current version of POSIX.1.)

              If the call is not governed by any standards but commonly exists
              on  other  systems,  note  them.  If the call is Linux-specific,
              note this.

              If this section consists of just a list of standards  (which  it
              commonly does), terminate the list with a period ('.').

       NOTES  Miscellaneous notes.

              For  Section 2 and 3 man pages you may find it useful to include
              subsections (SS) named Linux Notes and glibc Notes.

              In Section 2, use the heading C  library/kernel  differences  to
              mark  off  notes  that describe the differences (if any) between
              the C library wrapper function for a system  call  and  the  raw
              system call interface provided by the kernel.

       CAVEATS
              Warnings about typical user misuse of an API, that don't consti-
              tute an API bug or design defect.

       BUGS   A list of limitations,  known  defects  or  inconveniences,  and
              other questionable activities.

       EXAMPLES
              One  or  more examples demonstrating how this function, file, or
              command is used.

              For details on writing example programs,  see  Example  programs
              below.

       AUTHORS
              A list of authors of the documentation or program.

              Use  of  an AUTHORS section is strongly discouraged.  Generally,
              it is better not to clutter every page with a list of (over time
              potentially  numerous)  authors;  if  you write or significantly
              amend a page, add a copyright notice as a comment in the  source
              file.   If you are the author of a device driver and want to in-
              clude an address for reporting bugs, place this under  the  BUGS
              section.

       REPORTING BUGS
              The  man-pages  project  doesn't use a REPORTING BUGS section in
              manual pages.  Information on reporting bugs is instead supplied
              in  the  script-generated  COLOPHON  section.   However, various
              projects do use a REPORTING BUGS section.  It is recommended  to
              place it near the foot of the page.

       COPYRIGHT
              The  man-pages project doesn't use a COPYRIGHT section in manual
              pages.  Copyright information is instead maintained in the  page
              source.   In  pages  where this section is present, it is recom-
              mended to place it near the foot of the  page,  just  above  SEE
              ALSO.

       SEE ALSO
              A  comma-separated  list of related man pages, possibly followed
              by other related pages or documents.

              The list should be ordered by section number and then alphabeti-
              cally by name.  Do not terminate this list with a period.

              Where the SEE ALSO list contains many long manual page names, to
              improve the visual result of the output, it may be useful to em-
              ploy  the  .ad l (don't right justify) and .nh (don't hyphenate)
              directives.  Hyphenation of individual page names  can  be  pre-
              vented by preceding words with the string "\%".

              Given  the  distributed,  autonomous nature of FOSS projects and
              their documentation, it is sometimes necessary—and in many cases
              desirable—that  the SEE ALSO section includes references to man-
              ual pages provided by other projects.

FORMATTING AND WORDING CONVENTIONS
       The following subsections note some details  for  preferred  formatting
       and  wording  conventions  in various sections of the pages in the man-
       pages project.

   SYNOPSIS
       Wrap the function prototype(s) in a .nf/.fi pair to prevent filling.

       In general, where more than one function prototype is shown in the SYN-
       OPSIS, the prototypes should not be separated by blank lines.  However,
       blank lines (achieved using .PP) may be added in the following cases:

       •  to separate long lists of function prototypes  into  related  groups
          (see for example list(3));

       •  in other cases that may improve readability.

       In  the  SYNOPSIS,  a  long function prototype may need to be continued
       over to the next line.  The continuation line is indented according  to
       the following rules:

       (1)  If  there  is  a single such prototype that needs to be continued,
            then align the continuation line so that when the page is rendered
            on  a fixed-width font device (e.g., on an xterm) the continuation
            line starts just below the start of the argument list in the  line
            above.   (Exception:  the indentation may be adjusted if necessary
            to prevent a very long continuation line or a further continuation
            line where the function prototype is very long.)  As an example:

                int tcsetattr(int fd, int optional_actions,
                              const struct termios *termios_p);

       (2)  But, where multiple functions in the SYNOPSIS require continuation
            lines, and the function names have different lengths,  then  align
            all continuation lines to start in the same column.  This provides
            a nicer rendering in PDF output (because the SYNOPSIS uses a vari-
            able  width  font  where  spaces render narrower than most charac-
            ters).  As an example:

                int getopt(int argc, char * const argv[],
                           const char *optstring);
                int getopt_long(int argc, char * const argv[],
                           const char *optstring,
                           const struct option *longopts, int *longindex);

   RETURN VALUE
       The preferred wording to describe how errno is set is "errno is set  to
       indicate  the  error"  or similar.  This wording is consistent with the
       wording used in both POSIX.1 and FreeBSD.

   ATTRIBUTES
       Note the following:

       •  Wrap the table in this section in a .ad l/.ad pair to  disable  text
          filling and a .nh/.hy pair to disable hyphenation.

       •  Ensure  that  the table occupies the full page width through the use
          of an lbx description for one of the columns (usually the first col-
          umn,  though  in  some cases the last column if it contains a lot of
          text).

       •  Make free use of T{/T} macro pairs to allow table cells to be broken
          over  multiple  lines (also bearing in mind that pages may sometimes
          be rendered to a width of less than 80 columns).

       For examples of all of the above, see the source code of various pages.

STYLE GUIDE
       The following subsections describe the preferred  style  for  the  man-
       pages  project.   For  details not covered below, the Chicago Manual of
       Style is usually a good source; try also grepping for preexisting usage
       in the project source tree.

   Use of gender-neutral language
       As  far  as  possible,  use  gender-neutral language in the text of man
       pages.  Use of "they" ("them", "themself", "their") as a gender-neutral
       singular pronoun is acceptable.

   Formatting conventions for manual pages describing commands
       For  manual  pages that describe a command (typically in Sections 1 and
       8), the arguments are always specified using italics, even in the  SYN-
       OPSIS section.

       The name of the command, and its options, should always be formatted in
       bold.

   Formatting conventions for manual pages describing functions
       For manual pages that describe functions (typically in Sections  2  and
       3),  the arguments are always specified using italics, even in the SYN-
       OPSIS section, where the rest of the function is specified in bold:

           int myfunction(int argc, char **argv);

       Variable names should, like argument names, be specified in italics.

       Any reference to the subject of the current manual page should be writ-
       ten  with  the  name in bold followed by a pair of parentheses in Roman
       (normal) font.  For example, in the fcntl(2) man  page,  references  to
       the  subject  of  the page would be written as: fcntl().  The preferred
       way to write this in the source file is:

           .BR fcntl ()

       (Using this format, rather than the use of "\fB...\fP()" makes it  eas-
       ier to write tools that parse man page source files.)

   Use semantic newlines
       In  the source of a manual page, new sentences should be started on new
       lines, long sentences should be split into lines at clause breaks (com-
       mas,  semicolons,  colons, and so on), and long clauses should be split
       at phrase boundaries.  This convention, sometimes  known  as  "semantic
       newlines",  makes  it  easier to see the effect of patches, which often
       operate at the level of individual sentences, clauses, or phrases.

   Lists
       There are different kinds of lists:

       Tagged paragraphs
              These are used for a list of tags and their descriptions.   When
              the  tags  are  constants (either macros or numbers) they are in
              bold.  Use the .TP macro.

              An example is this "Tagged paragraphs" subsection is itself.

       Ordered lists
              Elements are preceded by  a  number  in  parentheses  (1),  (2).
              These represent a set of steps that have an order.

              When there are substeps, they will be numbered like (4.2).

       Positional lists
              Elements  are  preceded  by  a number (index) in square brackets
              [4], [5].  These represent fields in a  set.   The  first  index
              will be:

              0      When  it  represents  fields of a C data structure, to be
                     consistent with arrays.
              1      When it represents fields of a  file,  to  be  consistent
                     with tools like cut(1).

       Alternatives list
              Elements  are  preceded  by  a  letter  in parentheses (a), (b).
              These represent a set of (normally) exclusive alternatives.

       Bullet lists
              Elements are preceded by bullet symbols (\[bu]).  Anything  that
              doesn't fit elsewhere is usually covered by this type of list.

       Numbered notes
              Not  really  a  list, but the syntax is identical to "positional
              lists".

       There should always be exactly 2 spaces between the list symbol and the
       elements.  This doesn't apply to "tagged paragraphs", which use the de-
       fault indentation rules.

   Formatting conventions (general)
       Paragraphs should be separated by suitable markers (usually either  .PP
       or .IP).  Do not separate paragraphs using blank lines, as this results
       in poor rendering in some output formats (such as PostScript and PDF).

       Filenames (whether pathnames, or references to header files) are always
       in italics (e.g., <stdio.h>), except in the SYNOPSIS section, where in-
       cluded files are in bold (e.g., #include <stdio.h>).  When referring to
       a  standard  header file include, specify the header file surrounded by
       angle brackets, in the usual C way (e.g., <stdio.h>).

       Special macros, which are usually in uppercase, are in bold (e.g., MAX-
       INT).  Exception: don't boldface NULL.

       When  enumerating  a  list  of error codes, the codes are in bold (this
       list usually uses the .TP macro).

       Complete commands should, if long, be written as an  indented  line  on
       their own, with a blank line before and after the command, for example

           man 7 man-pages

       If the command is short, then it can be included inline in the text, in
       italic format, for example, man 7 man-pages.  In this case, it  may  be
       worth  using  nonbreaking spaces (\[ti]) at suitable places in the com-
       mand.  Command options should be written in italics (e.g., -l).

       Expressions, if not written on a  separate  indented  line,  should  be
       specified  in italics.  Again, the use of nonbreaking spaces may be ap-
       propriate if the expression is inlined with normal text.

       When showing example shell sessions, user input should be formatted  in
       bold, for example

           $ date
           Thu Jul  7 13:01:27 CEST 2016

       Any  reference  to  another man page should be written with the name in
       bold, always followed by the section number, formatted in  Roman  (nor-
       mal)  font,  without  any separating spaces (e.g., intro(2)).  The pre-
       ferred way to write this in the source file is:

           .BR intro (2)

       (Including the section number  in  cross  references  lets  tools  like
       man2html(1) create properly hyperlinked pages.)

       Control  characters should be written in bold face, with no quotes; for
       example, ^X.

   Spelling
       Starting with release 2.59, man-pages follows American spelling conven-
       tions  (previously,  there  was  a  random  mix of British and American
       spellings); please write all new pages and patches according  to  these
       conventions.

       Aside  from  the well-known spelling differences, there are a few other
       subtleties to watch for:

       •  American English tends to use the forms "backward",  "upward",  "to-
          ward",  and  so  on  rather than the British forms "backwards", "up-
          wards", "towards", and so on.

       •  Opinions are divided on "acknowledgement" vs "acknowledgment".   The
          latter  is predominant, but not universal usage in American English.
          POSIX and the BSD license use the former  spelling.   In  the  Linux
          man-pages project, we use "acknowledgement".

   BSD version numbers
       The  classical  scheme for writing BSD version numbers is x.yBSD, where
       x.y is the version number (e.g., 4.2BSD).  Avoid forms such as BSD 4.3.

   Capitalization
       In subsection ("SS") headings, capitalize the first word in  the  head-
       ing,  but  otherwise  use  lowercase, except where English usage (e.g.,
       proper nouns) or programming language  requirements  (e.g.,  identifier
       names) dictate otherwise.  For example:

           .SS Unicode under Linux

   Indentation of structure definitions, shell session logs, and so on
       When  structure definitions, shell session logs, and so on are included
       in running text, indent them by 4 spaces (i.e.,  a  block  enclosed  by
       .in +4n  and  .in),  format them using the .EX and .EE macros, and sur-
       round them with suitable paragraph markers (either .PP  or  .IP).   For
       example:

           .PP
           .in +4n
           .EX
           int
           main(int argc, char *argv[])
           {
               return 0;
           }
           .EE
           .in
           .PP

   Preferred terms
       The  following  table  lists  some preferred terms to use in man pages,
       mainly to ensure consistency across pages.

       Term                 Avoid using              Notes
       ────────────────────────────────────────────────────────────────
       bit mask             bitmask
       built-in             builtin

       Epoch                epoch                    For the UNIX
                                                     Epoch (00:00:00,
                                                     1 Jan 1970 UTC)
       filename             file name
       filesystem           file system
       hostname             host name
       inode                i-node
       lowercase            lower case, lower-case
       nonzero              non-zero
       pathname             path name
       pseudoterminal       pseudo-terminal
       privileged port      reserved port, system
                            port
       real-time            realtime, real time
       run time             runtime
       saved set-group-ID   saved group ID, saved
                            set-GID
       saved set-user-ID    saved user ID, saved
                            set-UID
       set-group-ID         set-GID, setgid
       set-user-ID          set-UID, setuid
       superuser            super user, super-user
       superblock           super block, super-
                            block
       symbolic link        symlink
       timestamp            time stamp
       timezone             time zone
       uppercase            upper case, upper-case
       usable               useable
       user space           userspace
       username             user name
       x86-64               x86_64                   Except if refer-
                                                     ring to result
                                                     of "uname -m" or
                                                     similar
       zeros                zeroes

       See also the discussion Hyphenation of attributive compounds below.

   Terms to avoid
       The following table lists some terms to avoid using in man pages, along
       with some suggested alternatives, mainly to ensure consistency across
       pages.

       Avoid             Use instead         Notes
       ──────────────────────────────────────────────────────────

       32bit             32-bit              same for 8-bit,
                                             16-bit, etc.
       current process   calling process     A common mistake
                                             made by kernel pro-
                                             grammers when writ-
                                             ing man pages
       manpage           man page, manual
                         page
       minus infinity    negative infinity
       non-root          unprivileged user
       non-superuser     unprivileged user
       nonprivileged     unprivileged
       OS                operating system
       plus infinity     positive infinity
       pty               pseudoterminal
       tty               terminal
       Unices            UNIX systems
       Unixes            UNIX systems

   Trademarks
       Use the correct spelling and case for trademarks.  The following  is  a
       list  of  the correct spellings of various relevant trademarks that are
       sometimes misspelled:

              DG/UX
              HP-UX
              UNIX
              UnixWare

   NULL, NUL, null pointer, and null byte
       A null pointer is a pointer that points to nothing, and is normally in-
       dicated by the constant NULL.  On the other hand, NUL is the null byte,
       a byte with the value 0, represented in C via  the  character  constant
       '\0'.

       The  preferred term for the pointer is "null pointer" or simply "NULL";
       avoid writing "NULL pointer".

       The preferred term for the byte is "null byte".  Avoid  writing  "NUL",
       since  it  is  too  easily  confused with "NULL".  Avoid also the terms
       "zero byte" and "null character".  The byte that terminates a C  string
       should  be described as "the terminating null byte"; strings may be de-
       scribed as "null-terminated", but avoid the use of "NUL-terminated".

   Hyperlinks
       For hyperlinks, use the .UR/.UE macro pair  (see  groff_man(7)).   This
       produces proper hyperlinks that can be used in a web browser, when ren-
       dering a page with, say:

           BROWSER=firefox man -H pagename

   Use of e.g., i.e., etc., a.k.a., and similar
       In general, the use of abbreviations such as  "e.g.",  "i.e.",  "etc.",
       "cf.",  and "a.k.a." should be avoided, in favor of suitable full word-
       ings ("for example", "that is", "and so on", "compare to", "also  known
       as").

       The  only  place where such abbreviations may be acceptable is in short
       parenthetical asides (e.g., like this one).

       Always include periods in such abbreviations, as shown here.  In  addi-
       tion, "e.g." and "i.e." should always be followed by a comma.

   Em-dashes
       The  way  to  write  an em-dash—the glyph that appears at either end of
       this subphrase—in *roff is with the macro "\[em]".  (On an ASCII termi-
       nal,  an  em-dash  typically renders as two hyphens, but in other typo-
       graphical contexts it renders as a long  dash.)   Em-dashes  should  be
       written without surrounding spaces.

   Hyphenation of attributive compounds
       Compound  terms  should be hyphenated when used attributively (i.e., to
       qualify a following noun). Some examples:

              32-bit value
              command-line argument
              floating-point number
              run-time check
              user-space function
              wide-character string

   Hyphenation with multi, non, pre, re, sub, and so on
       The general tendency in modern English is not to hyphenate  after  pre-
       fixes  such  as  "multi", "non", "pre", "re", "sub", and so on.  Manual
       pages should generally follow this rule when these prefixes are used in
       natural English constructions with simple suffixes.  The following list
       gives some examples of the preferred forms:

              interprocess
              multithreaded

              multiprocess
              nonblocking
              nondefault
              nonempty
              noninteractive
              nonnegative
              nonportable
              nonzero
              preallocated
              precreate
              prerecorded
              reestablished
              reinitialize
              rearm
              reread
              subcomponent
              subdirectory
              subsystem

       Hyphens should be retained when the prefixes are  used  in  nonstandard
       English  words,  with  trademarks,  proper nouns, acronyms, or compound
       terms.  Some examples:

              non-ASCII
              non-English
              non-NULL
              non-real-time

       Finally, note that "re-create" and "recreate" are two different  verbs,
       and the former is probably what you want.

   Generating optimal glyphs
       Where a real minus character is required (e.g., for numbers such as -1,
       for man page cross references such as utf-8(7), or when writing options
       that  have a leading dash, such as in ls -l), use the following form in
       the man page source:

           \-

       This guideline applies also to code examples.

       The use of real minus signs serves the following purposes:

       •  To provide better renderings on various  targets  other  than  ASCII
          terminals, notably in PDF and on Unicode/UTF-8-capable terminals.

       •  To generate glyphs that when copied from rendered pages will produce
          real minus signs when pasted into a terminal.

       To produce unslanted single quotes that render well  in  ASCII,  UTF-8,
       and PDF, use "\[aq]" ("apostrophe quote"); for example

           \[aq]C\[aq]

       where  C is the quoted character.  This guideline applies also to char-
       acter constants used in code examples.

       Where a proper caret (^) that renders well in both a terminal  and  PDF
       is  required,  use  "\[ha]".  This is especially necessary in code sam-
       ples, to get a nicely rendered caret when rendering to PDF.

       Using a naked "~" character results in a poor rendering  in  PDF.   In-
       stead  use  "\[ti]".   This is especially necessary in code samples, to
       get a nicely rendered tilde when rendering to PDF.

   Example programs and shell sessions
       Manual pages may include example programs demonstrating how  to  use  a
       system call or library function.  However, note the following:

       •  Example programs should be written in C.

       •  An  example  program is necessary and useful only if it demonstrates
          something beyond what can easily be provided in a  textual  descrip-
          tion  of  the interface.  An example program that does nothing other
          than call an interface usually serves little purpose.

       •  Example programs should ideally be short (e.g., a good  example  can
          often  be  provided  in less than 100 lines of code), though in some
          cases longer programs may be necessary to  properly  illustrate  the
          use of an API.

       •  Expressive code is appreciated.

       •  Comments should included where helpful.  Complete sentences in free-
          standing comments should be terminated by a period.  Periods  should
          generally  be  omitted  in  "tag"  comments (i.e., comments that are
          placed on the same line of code); such comments are in any case typ-
          ically brief phrases rather than complete sentences.

       •  Example programs should do error checking after system calls and li-
          brary function calls.

       •  Example programs should be complete, and  compile  without  warnings
          when compiled with cc -Wall.

       •  Where possible and appropriate, example programs should allow exper-
          imentation, by varying their behavior based on inputs (ideally  from
          command-line arguments, or alternatively, via input read by the pro-
          gram).

       •  Example programs should be  laid  out  according  to  Kernighan  and
          Ritchie  style, with 4-space indents.  (Avoid the use of TAB charac-
          ters in source code!)  The following command can be used  to  format
          your source code to something close to the preferred style:

              indent -npro -kr -i4 -ts4 -sob -l72 -ss -nut -psl prog.c

       •  For  consistency, all example programs should terminate using either
          of:

              exit(EXIT_SUCCESS);
              exit(EXIT_FAILURE);

          Avoid using the following forms to terminate a program:

              exit(0);
              exit(1);
              return n;

       •  If there is extensive explanatory text  before  the  program  source
          code,  mark  off  the  source code with a subsection heading Program
          source, as in:

              .SS Program source

          Always do this if the explanatory text includes a shell session log.

       If you include a shell session log demonstrating the use of  a  program
       or other system feature:

       •  Place the session log above the source code listing.

       •  Indent the session log by four spaces.

       •  Boldface the user input text, to distinguish it from output produced
          by the system.

       For some examples of  what  example  programs  should  look  like,  see
       wait(2) and pipe(2).

EXAMPLES
       For canonical examples of how man pages in the man-pages package should
       look, see pipe(2) and fcntl(2).

SEE ALSO
       man(1), man2html(1),  attributes(7),  groff(7),  groff_man(7),  man(7),
       mdoc(7)

Linux man-pages 6.03              2023-02-05                      man-pages(7)

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