crafty(6) crafty(6)
NAME
crafty - chess engine
SYNOPSIS
crafty [bookpath=<directory>] [logpath=<directory>]
[tbpath=<directory-list>]
DESCRIPTION
Crafty is a chess "engine". That is, the program concerns itself with
playing chess and not with providing a graphic user interface. Thus
Crafty is commonly invoked indirectly via XBoard, and current versions
of these programs generally work very well together. Some noteworthy
features of Crafty are:
* Source code, provided, is unusually deserving of study. The author
has sought to provide a starting point for others writing chess-
playing programs, leading to clean and portable code. Another ob-
jective has been to maintain a state-of-the-art chess engine, with
the result that some parts of the source code may be challenging to
understand.
* Flexible and powerful command-line interface. About the only thing
that can not be done within the CLI is changing various paths deter-
mining where Crafty reads and writes various files. This manual
page focuses on explaining these paths.
* Easy graphic user interface via xboard(6).
* Informative log files. Writes "game.nnn" file storing current game
in PGN format, and also writes "log.nnn" file recording what the en-
gine was "thinking".
* Intelligent opening play. Crafty learns from experience, and makes
appropriate modifications to its opening book. The "book" command
allows generation of an opening book (from PGN data), and customiza-
tion of how it is used. The learning facilities synthesize several
different approaches, and allow various ways for the user to custom-
ize and follow what is being learned. Additional commands allow easy
creation of files to customize how Crafty plays the opening against
humans and against other computer programs.
* Uses endgame tablebases. Precompiled tablebases in the appropriate
format are freely downloadable from ftp://ftp.cis.uab.edu/hyatt/TB.
* Polished and powerful facilities for Internet play (for which the
program continues to be extensively used). Note that the licencing
forbids concealing Crafty under another name, or unauthorized entry
of it in a tournament in which other computer programs have been in-
vited to compete.
* Annotation. Generates either PGN or HTML files, in a manner made
very flexible by choosing appropriate aptions to the "annotate | an-
notateh" command.
OPTIONS
In the command line arguments, <directory-spec> is a path to a direc-
tory, whereas <directory-list> is a non-empty sequence of paths to di-
rectories. For portability, several different characters are taken as
path separators: the colon (:), the semicolon (;), and the comma (,).
There are actually four of these: bookpath is where Crafty seeks its
opening books and writes learned knowledge; logpath is where Crafty
normally writes a pair of files "game.nnn" and "log.nnn" for each game
it plays; rcpath is where Crafty looks for a run control file to be
read only; and tbpath is where Crafty looks for endgame tablebase files
to be read only.
The four path specifications have a number of things in common: each
has a default value set when Crafty is compiled, which can then be mod-
ified by the appropriate environment variable, and can then again be
modified by an invocation argument, but can not be modified after the
engine has been initialized (thus, in particular, it is not possible to
modify the paths by editing a run control file). Possibly the best
procedure is to avoid the invocation options, experiment with the envi-
ronment variables, and then perhaps recompile the program with differ-
ent defaults. Note that if the program is compiled "out of the box"
then all four values default to "./" (the directory in which Crafty has
been launched).
Crafty can be invoked with other arguments (such as "xboard" to indi-
cate that Crafty is being invoked through xboard(6)) which would not
usually be used directly.
COMMANDS
Crafty's extensive command-line interface is defined in "option.c",
discussed in "crafty.doc", and briefly described by the command "help".
FILES
Run control
Crafty tries to read a run control file rcpath/.craftyrc. (On a non-
Unix system, ".craftyrc" changes to "crafty.rc".) Such a file should
contain a sequence of valid Crafty commands, terminated by the command
"exit" to restore standard input to the keyboard. See craftyrc(5) for
a skeletal example.
Logging
When a game is played, Crafty normally writes "logpath/game.<nnn>" and
"logpath/log.<nnn>". Details of what is written are modifiable by the
`log' command. Because $CRAFTY_LOG_DIR defaults to "./" (the directory
in which Crafty is launched), trouble can occur if the program is
launched in a directory to which it is unable to write. Note that the
"log.<nnn>" file normally contains all output that would be visible if
Crafty were run from the command line but is usually hidden when it is
run from a GUI.
Opening books
Crafty is designed to maintain its chess opening knowledge in a file
"book.bin", and to modify this file as it learns from its mistakes.
Refer to the documentation for the "book" command for information on
generating and customizing usage of "book.bin".
Further, files "books.bin" and "bookc.bin" allow easy customization of
Crafty's opening play (against humans and computer, respectively). See
the documentation for the "books" command.
Finally, there are several files "*.lrn" for synopses of what Crafty
has been learning. See the documentation for the "learn" command.
Endgame tablebases
When normally configured, Crafty reads late endgame knowledge from
"*.emd" files, which are distance-to-mate tablebases. See the documen-
tation for the "egtb" command.
ENVIRONMENT VARIABLES
CRAFTY_BOOK_PATH
If $CRAFTY_BOOK_PATH is set, it overrides the compiled value of book-
path, the path to directory containing "book.bin" and friends. Unless
learning has been disabled, Crafty will be writing in this directory.
CRAFTY_LOG_PATH
If $CRAFTY_LOG_PATH is set, it overrides the compiled value of logpath,
the path to directory for writing, but not reading, the log files.
CRAFTY_RC_PATH
If $CRAFTY_RC_PATH is set, it overrides the compiled value of rcpath,
the path to directory for reading, but not writing, a run control file
(".craftyrc" or "crafty.rc").
CRAFTY_TB_PATH
If $CRAFTY_TB_PATH is set, it overrides the compiled value of tbpath,
the sequence of paths to directories for reading, but not writing,
endgame tablebase files.
SEE ALSO
craftyrc(5), xboard(6), /usr/share/doc/crafty
HISTORY
Crafty is the son of Cray Blitz, also written by Bob Hyatt. The subse-
quent history of Crafty is detailed in the source file "main.c". Open-
ing books appeared in version 1.9. log files in 1.11, endgame table-
bases in 8.24, run control files in 9.22, and environment variables in
16.5.
BUGS
In the interests of portability, Crafty deals with files in a simple
manner, at the cost of robustness. Very long or incorrect paths may
result in a "segmentation fault" when a file writing operation fails.
This manual page itself will probably always be flagrantly incomplete
in that many essential, powerful, and interesting aspects of Crafty are
not even mentioned.
AUTHOR
Robert Hyatt (hyatt@cis.uab.edu).
Crafty 19.8 December 22, 2003 crafty(6)
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