gnuchess

gnuchess [OPTION]... [FILE]
gnuchess

-x
    Starts Gnuchess in Xboard (Chess Engine Communication Protocol) mode, typically used when run by the Xboard GUI.

-u
    Starts Gnuchess in UCI (Universal Chess Interface) mode, allowing it to communicate with UCI-compatible chess GUIs.

-b
    Activates batch mode, where Gnuchess runs non-interactively, processing input from a file or standard input without human interaction. Useful for scripting.

-h, --help
    Displays a comprehensive help message with all available command-line options and their descriptions.

-v, --version
    Prints the version information of the Gnuchess program and exits.

-d <depth>
    Sets the maximum search depth for the engine, limiting how many moves ahead the engine calculates. For example, -d 8 limits the search to 8 plies.

-m <minutes>
    Sets the maximum time per move in minutes. For example, -m 5 gives the engine 5 minutes per move.

--hash-size <MB>
    Specifies the size of the transposition hash table in megabytes. A larger hash table can improve performance for deeper searches.

--fen <FEN string>
    Initializes the chess board with a specific position defined by a Forsyth-Edwards Notation (FEN) string.

--opening-book <file>
    Loads a specific opening book file, which Gnuchess uses to choose moves during the opening phase of the game.

--threads <num>
    Sets the number of CPU threads the engine should use for its search. Useful for multi-core processors to speed up analysis.

Gnuchess is a robust, free software chess program developed as part of the GNU Project. It provides a powerful chess engine capable of playing against human opponents, analyzing chess positions, and serving as a backend for graphical user interfaces (GUIs).

While it can be used interactively directly from the command line, its primary strength lies in its support for standard chess engine protocols like Xboard (also known as Chess Engine Communication Protocol) and UCI (Universal Chess Interface). This allows Gnuchess to be integrated seamlessly with popular chess GUIs such as Xboard, Arena, or Scid vs. PC, providing a rich visual experience.

Users can configure various aspects of the engine's play, including search depth, time limits, hash table size, and opening book usage, making it a versatile tool for both casual play and serious chess study.

While Gnuchess is a powerful engine, its direct command-line interface can be challenging for beginners. For a visual and user-friendly experience, it is highly recommended to use Gnuchess in conjunction with a graphical chess interface that supports Xboard or UCI protocols. Performance can vary significantly based on system resources and configured hash table size.

When run without -x or -u, Gnuchess operates in interactive mode. Users can type commands directly into the terminal to control the game. Key commands include:

• move e2e4: Make a move (e.g., pawn from e2 to e4).
• new: Start a new game.
• undo: Undo the last move.
• redo: Redo an undone move.
• resign: Resign the game.
• analyze: Enter analysis mode.
• set <option> <value>: Set engine options (e.g., set depth 10).
• show options: Display current engine settings.
• quit: Exit Gnuchess.

Gnuchess is most commonly used as an engine for graphical user interfaces. For Xboard, you typically start Xboard and then specify Gnuchess as an engine (e.g., xboard -fcp gnuchess). For UCI clients like Arena or Scid vs. PC, you would add Gnuchess as a new engine, pointing to its executable path and selecting the UCI protocol. This integration provides features like board visualization, move lists, and advanced analysis tools.

Gnuchess is one of the oldest and most enduring free software chess programs, with its origins tracing back to 1984 when it was created by Stuart Cracraft. It quickly became an integral part of the GNU Project, embodying the principles of free and open-source software.

Over the decades, Gnuchess has undergone continuous development, adapting to new computing paradigms and integrating advanced chess algorithms. Its evolution has included support for standard protocols like Xboard and UCI, enabling its widespread use with various graphical interfaces and participation in computer chess tournaments. It remains a foundational component for many chess enthusiasts and developers within the Linux and free software communities.

xboard(6), crafty(6), stockfish(6), leela-chess-zero(6)