gnuchess(6)                      Games Manual                      gnuchess(6)

       gnuchess - Chess

       gnuchess [ [[-|+]a] [-A aging-rate] [-b bookfile] [-B binbookfile] [-C
       cache-table-size] [-c] [[-|+]D ] [[-|+]E ] [[-|+]e ] [[-|+]F ] [-H
       hash-depth] [[-|+]h ] [-L language] [-l listfile] [[-|+]N] [[-|+]p ]
       [-P plys] [-r length] [-s savefile] [-S binbooksize] [-t] [-c hashfile-
       size] [-T transition-table-size] [[-|+]V] [-v] [-x] [-z search-fuzz]
       arg1 arg2 ]

       Gnuchess plays a game of chess against the user or it plays against

       Gnuchess is an updated version of the GNU chess playing program.  It
       has a simple alpha-numeric board display, an IBM PC compatible
       interface, or it can be compiled for use with the chesstool program on
       a SUN workstation or with the xboard program under X-windows.  To
       invoke the program type:

              - simple curses based version

              - fancy version using curses and inverse video on UNIX, or IBM
              PC cursor controls and characters on MSDOS

              - ASCII based version

              - chesstool compatible version

              - xboard compatible version

       If one argument is given, it is the search time per move in
       [minutes:]seconds.  So gnuchess 30 will generate one move every 30
       seconds, while gnuchess 5:00 will generate one move every 5 minutes.

       If two or more arguments are given, they will be used to set tournament
       time controls with the first argument of each pair being the number of
       moves and the second being the total clock time in minutes[:seconds].
       Thus, entering gnuchess 60 5 will set the clocks for 5 minutes (300
       seconds) for the first 60 moves, and gnuchess 30 3:30 will allow 3
       minutes and 30 seconds for 30 moves.

       gnuchess 30 5 1 :30 will allow 5 minutes for the first 30 moves and 30
       seconds for each move after that.  Up to 4 pairs of controls may be

       If no argument is given the program will prompt the user for level of

       For use with chesstool or xboard, see the documentation on those

       At startup Gnuchess reads the binbook file if it is present. It then
       looks for a book file. If it is present it adds its contents to the
       binbook data. If the binbook file is writable a new combined binbook
       file is written.

       The book consists of a sequence of openings.  An opening
       begins with a line starting with a !  , the rest of the line is
       comments.  Following this is a series of moves in algebraic notation
       alternating white and black separated by white space. A move may have a
       ?  after it indicating this move should never be made in this position.
       Moves are stored as position:move so transpositions between openings
       can take place.

       The hashfile if created should be on the order of 4 megabytes or
       gnuchess -c 22.  This file contains positions and moves learned from
       previous games.  If a hashfile is used the computer makes use of the
       experience it gained in past games. Tests run so far show that it plays
       no worse with the hashfile than without, but it is not clear yet
       whether it provides a real advantage.

       Note: Piece letters and legal castling notation is determined by the
       language file.  What is specified here is the default English.

       Once gnuchess is invoked, the program will display the board and prompt
       the user for a move. To enter a move, use the notation e2e4 where the
       first letter-number pair indicates the origination square and the
       second letter-number pair indicates the destination square.  An
       alternative is to use the notation nf3 where the first letter indicates
       the piece type (p,n,b,r,q,k).  To castle, type the origin and
       destination squares of the king just as you would do for a regular
       move, or type o-o or 0-0 for kingside castling and o-o-o or 0-0-0 for
       queenside.  To promote a pawn append the type of the new piece to the
       move, as in e7e8q or c7c8r.

       -L lang
              Use language lang from the file gnuchess.lang.  If -L is not
              specified it defaults to the language used in the first line in
              the file.  gnuchessr -L ger will use the german language.

       -A aging-rate
              Specify aging rate for hash table entries

       [-]a   Do [do not] search on opponents time.

       -b bookfile
              Use bookfile for opening book.

       -B binbookfile
              Use binbookfile for binary opening book.

       -C cache-size
              Specify evaluation cache table size (in entries).

       -D     Toggle DEEPNULL at runtime.

       -E     Toggle flag.threat.

       -e     Toggle flag.neweval to force evaluations instead of estimates

       -F     Toggle flag.noscore

       -H hash-depth
              pecify depth in plys for hashing.

       -S size
              Size of binbookfile for memory based and GDX books. For creating
              a binbookfile.

       -P plylevels
              Number of plys to include in the binbookfile. For generating a

       -p     Toggle flag.pvs

       -c size
              Create a new HASHFILE. File size is 2^size entries of
              approximately 65 bytes.

       [-]h   Do [do not] use hashfile.

       -l pathname
              Pathname of the loadfile use with the get or xget.

       -r length
              Rehash length times in searching  entries for position in
              transposition table.

       -s pathname
              Pathname of the save file to use with the save command.

       -t     Show statistics for HASHFILE

       -T size
              Set the transposition table size to size entries. (minimum is

       -v     Show version and patchlevel.

       -x value
              Use value as the evaluation window xwndw.

       In addition to legal moves, the following commands are available as
       responses.  Note: command names are determined by the language file and
       may vary with the implementation. This is default English.

       alg -- allow algebraic input (not implemented)

       Awindow -- change Alpha window (default score + 90)

       Bwindow -- change Beta window (default score - 90)

       beep -- causes the program to beep after each move.

       bd -- updates the current board position on the display.

       bk -- Print out all moves for this position from the book as: move
       response value

       book -- turns off use of the opening library.

       both -- causes the computer to play both sides of a chess game.

       black -- causes the computer to take the black pieces.  If the computer
       is to move first the go command must be given.

       eco -- Print out opening information for this game - lists ECO # and

       coords -- show coordinates on the display (visual only)

       contempt -- allows the value of contempt to be modified.

       debug --  asks for a piece as color piece, as wb or bn, and shows its
       calculated value on each square.

       debuglevel --  sets level of debugging output if compiled with debug

       depth -- allows the user to change the search depth of the program.
       The maximum depth is 29 ply.  Normally the depth is set to 29 and the
       computer terminates its search based on elapsed time rather than depth.
       If depth is set to (say) 4 ply, the program will search until all moves
       have been examined to a depth of 4 ply (with extensions up to 11
       additional ply for sequences of checks and captures).  If you set a
       maximum time per move and also use the depth command, the search will
       stop at the specified time or the specified depth, whichever comes

       easy -- toggles easy mode (thinking on opponents time) on and off. The
       default is easy mode ON.  If easy mode is disabled, the keyboard is
       polled for input every so often and when input is seen the search is
       terminated. It may also be terminated with a sigint.

       edit -- allows the user to set up a board position.

            # - command will clear the board.

            c - toggle piece color.

            .  - command will exit setup mode.

       pb3 - place a pawn on b3

       Pieces are entered by typing a letter (p,n,b,r,q,k) for the piece
       followed by the coordinate.

       The usual warning about the language file applies.

       exit -- exits gnuchess.

       first -- tells the computer to move first. Computer begins searching
       for a move.  (same as "go").

       force -- allows the user to enter moves for both sides. To get the
       program to play after a sequence of moves has been entered use the
       'white' or 'black' command followed by 'go'.

       gamein -- toggles game mode time control. Assumes the time specified
       for time control is the time for a complete game. Input with the level
       command should be the game time and the expected number of moves in a

       get -- retrieves a game from disk.  The program will prompt the user
       for a file name.

       go -- tells the computer to move first. Computer begins searching for a
       move.  (same as "first").

       hash -- use/don't use hashfile.

       hard -- think on opponents time

       hashdepth -- allows the user to change the minimum depth for using the
       hashfile and the number of moves from the begining of the game to use

       help -- displays a short description of the commands and the current
       status of options.

       hint -- causes the program to supply the user with its predicted move.

       level -- allows the user to set time controls such as 60 moves in 5
       minutes etc.  In tournament mode, the program will vary the time it
       takes for each move depending on the situation.  If easy mode is
       disabled (using the 'easy' command), the program will often respond
       with its move immediately, saving time on its clock for use later on.

       list -- writes the game moves and some statistics on search depth,
       nodes, and time to the file 'chess.lst'.

       material -- toggle material flag - draws on no pawns and both sides <

       Mwpawn, Mbpawn, Mwknight, Mbknight, Mwbishop, Mbbishop -- print out
       static position evaluation table

       new -- starts a new game.

       p -- evaluates the board and shows the point score for each piece. The
       total score for a position is the sum of these individual piece scores.

       post -- causes the program to display the principle variation and the
       score during the search.  A score of 100 is equivalent to a 1 pawn
       advantage for the computer.

       unpost -- turn off the post display.

       quit -- exits the game.

       random -- causes the program to randomize its move selection slightly.

       rcptr -- set recapture mode.

       remove -- backout the last level for both sides. Equal to 2 undo's.

       reverse -- causes the board display to be reversed.  That is, the white
       pieces will now appear at the top of the board.

       rv -- reverse board display.

       setup -- Compatibility with Unix chess and the nchesstool. Set up a
       board position.  Eight lines of eight characters are used to setup the
       board. a8-h8 is the first line. Black pieces are  represented  by
       uppercase characters.

       stars -- (gnuchessn only) add stars (*) to black pieces.

       save -- saves a game to disk.  The program will prompt the user for a
       file name.

       switch -- causes the program to switch places with the opponent and
       begin searching.

       test -- performs some speed tests for MoveList and CaptureList
       generation, and ScorePosition position scoring for the current board.

       time otim -- time set computers time remaining, intended for
       synchronizing clocks among multiple players.  -- otim set opponents
       time remaining, intended for synchronizing clocks among multiple

       undo -- undoes the last move whether it was the computer's or the
       human's. You may also type "remove". This is equivalent to two "undo's"
       (e.g. retract one move for each side).

       white -- causes the computer to take the white pieces.  If the computer
       is to move first the go command must be given.

       xget -- read an xboard position file.

       xwndw -- change X window. The window around alpha/beta used to
       determine whether the position should be scored or just estimated.