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	vertical  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-central 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 number 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 position
	      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 suitable
	      for chdb).

       Patterns select subsets of the games.  A pattern is one of the following, 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 transpositions.

       /regular expression/fields
	      This pattern matches the regular expression against the various text windows.  Fields is a list of characters from the  set  abdefo-
	      prw.   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)