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CHDB(7)                Miscellaneous Information Manual                CHDB(7)



NAME
       chdb - chess database browser

SYNOPSIS
       chdb [ file ...  ]

DESCRIPTION
       Chdb reads the given files of chess games (hist by default) and accepts
       commands to search, play through, and display the games in these files.
       If  x  is  the  name  of  the file, it is looked for under the names x,
       x.m.out, and /lib/chess/x.m.out.

       After reading the files, chdb displays a chess  board,  a  text  window
       with  a command line, and vertical and horizontal scroll bars along the
       edges of the board.  The text window holds 6 lines of information about
       the  game  and  position and, at the bottom, a command line in which to
       type.  The displayed text contains chess symbols--use a suitable font.

       The vertical scroll bar scans through the games to select a  game;  the
       horizontal bar then scans through the moves of the selected game.  Both
       scroll bars use button 1 to scan backwards, button 3 to scan  forwards,
       and  button  2  to jump to an absolute position.  With buttons 1 and 3,
       the scroll bars are calibrated in units of 1 through 8 corresponding to
       the  ranks and files of the board.  The units measure games on the ver-
       tical scroll bar, ply (half-moves) on the horizontal scroll  bar.   For
       example,  clicking  button  3  on the horizontal scroll bar under the d
       file steps through the game two full moves.

       Moves may be made on the chess board by pointing with button 1.   There
       are  two methods to point at moves.  For the first method, point at the
       piece to be moved, press button 1, point to  the  place  to  move  that
       piece,  and release button 1.  In the second method, point at the place
       where a piece is to move and press button 1.   The  smallest/least-cen-
       tral  piece  that  can  move  there is highlighted.  Releasing button 1
       without moving the mouse will make the highlighted  move.   Moving  the
       mouse  to  the  desired  piece  and  releasing the button will move the
       selected piece.

       Typed lines of text are echoed in the command line and  executed.   The
       available commands are:

       f n n  Set  the  format  for  display of moves in the text window.  The
              first number is the verbosity, with 0 minimal.  The second  num-
              ber  is  0  for  algebraic,  1  for  English, and 2 for figurine
              (default).

       g n    Go to the game with ordinal number n in the input files.   If  n
              is prefixed with a + or -, it is interpreted as a relative posi-
              tion in the current set of games (see below).  N defaults to +1.

       p n    Go to whole move n in the current game.  If n is prefixed with a
              +  or  -, it is interpreted as an offset in ply from the current
              position.  N defaults to +1.

       k n    Mark the current set of games with tag n (see patterns, below).

       w type file
              Write the current set of games to file.  Type is either a (write
              the  games as text) or m (write the games in binary format suit-
              able for chdb).

       Patterns select subsets of the games.  A pattern is one of the  follow-
       ing,  in  decreasing  precedence  order.   Parentheses  can be used for
       grouping.

       .      The current game.

       *      All games originally read.

       'n     The games previously marked with a k command with the same n.

       []

       [number]
              All games in * that contain the positions that can be reached in
              the  specified  number  of  plies  from the current position.  A
              missing number is the same as zero,  meaning  just  the  current
              position.   Positions  are  matched  with black/white transposi-
              tions.

       /regular expression/fields
              This pattern matches the regular expression against the  various
              text windows.  Fields is a list of characters from the set abde-
              foprw.  A is for all, b for black, d for date, e  for  event,  f
              for  file,  o for opening, p for person (white and black), r for
              result, and w for white.  If  multiple  fields  are  given,  the
              expression  is matched on the union of the specified fields.  If
              no field is given, p is assumed.

       !pattern
              The set subtraction of * and the given pattern.

       pattern-pattern
              The set subtraction of the given patterns.

       pattern+pattern

       pattern|pattern
              The set union of the given patterns.

       pattern pattern

       pattern&&pattern
              The set intersection of the given patterns.

       +pattern

       -pattern

       &&pattern

       |pattern
              These patterns have the current set of games as an implied first
              operand.

EXAMPLE
       Select games that Botvinnik lost:

              (/Botv/w/0-1/r)|(/Botv/b/1-0/r)

FILES
       /lib/chess
              directory of databases.

SOURCE
       /sys/src/cmd/chdb

SEE ALSO
       regexp(6).

BUGS
       The browser is only a prototype.

       Most of the databases are protected by copyright and not distributed.



                                                                       CHDB(7)