XBoard is a graphical chessboard that can serve as a user interface to chess engines (such as GNU Chess), the Internet Chess Servers, electronic mail correspondence chess, or your own collection of saved games.
This manual documents version 4.4.0j of XBoard.
XBoard always runs in one of four major modes. You select the major mode from the command line when you start up XBoard.
To move a piece, you can drag it with the left mouse button, or you can click the left mouse button once on the piece, then once more on the destination square. To drop a new piece on a square (when applicable), press the middle or the right mouse button over the square and select from the popup menu. In cases where you can drop either a white or black piece, use the middle button (or shift+right) for white and the right button (or shift+middle) for black. When you are playing a bughouse game on an Internet Chess Server, a list of the offboard pieces that each player has available is shown in the window title after the player's name; in addition, the piece menus show the number of pieces available of each type. From version 4.3.14 on, it is also possible in crazyhouse, bughouse or shogi to dag and drop pieces to the board from the holdings squares displayed next to the board.
All other XBoard commands are available from the menu bar. The most frequently used commands also have shortcut keys or on-screen buttons.
When XBoard is iconized, its graphical icon is a white knight if it is White's turn to move, a black knight if it is Black's turn. See Iconize in Keys below if you have problems getting this feature to work.
The game file parser will accept PGN (portable game notation),
or in fact almost any file that contains moves in algebraic
notation.
Notation of the form ‘P@f7’
is accepted for piece-drops in bughouse games;
this is a nonstandard extension to PGN.
If the file includes a PGN position (FEN tag), or an old-style
XBoard position diagram bracketed by ‘[--’ and ‘--]’
before the first move, the game starts from that position. Text
enclosed in parentheses, square brackets, or curly braces is assumed to
be commentary and is displayed in a pop-up window. Any other
text in the file is ignored. PGN variations (enclosed in
parentheses) are treated as comments; XBoard is not able to walk
variation trees.
The nonstandard PGN tag [Variant "varname"] functions similarly to
the -variant command-line option (see below), allowing games in certain chess
variants to be loaded. There is also a heuristic to
recognize chess variants from the Event tag, by looking for the strings
that the Internet Chess Servers put there when saving variant ("wild") games.
oldSaveStyle
option is true, in which case they are saved in an older,
human-readable format that is specific to XBoard. Both formats
can be read back by the ‘Load Position’ command.
To set up a position to analyze, you do the following:
1. Select Edit Position from the Mode Menu
2. Set up the position. Use the middle and right buttons to bring up the white and black piece menus.
3. When you are finished, click on either the Black or White clock to tell XBoard which side moves first.
4. Select Analysis Mode from the Mode Menu to start the analysis.
The analysis function can also be used when observing games on an ICS
with an engine loaded (zippy mode); the engine then will analyse
the positions as they occur in the observed game.
To use xboard in ICS mode, run it in the foreground with the -ics option, and use the terminal you started it from to type commands and receive text responses from the chess server. See Chess Servers below for more information.
XBoard activates some special position/game editing features when you
use the examine or bsetup commands on ICS and you have
‘ICS Client’ selected on the Mode menu. First, you can issue the
ICS position-editing commands with the mouse. Move pieces by dragging
with mouse button 1. To drop a new piece on a square, press mouse
button 2 or 3 over the square. This brings up a menu of white pieces
(button 2) or black pieces (button 3). Additional menu choices let
you empty the square or clear the board. Click on the White or Black
clock to set the side to play. You cannot set the side to play or
drag pieces to arbitrary squares while examining on ICC, but you can
do so in bsetup mode on FICS. In addition, the menu commands
‘Forward’, ‘Backward’, ‘Pause’, and ‘Stop Examining’
have special functions in this mode; see below.
In chess engine mode, the chess engine continues to check moves for legality but does not participate in the game. You can bring the chess engine into the game by selecting ‘Machine White’, ‘Machine Black’, or ‘Two Machines’.
In ICS mode, the moves are not sent to the ICS: ‘Edit Game’ takes
XBoard out of ICS Client mode and lets you edit games locally.
If you want to edit games on ICS in a way that other ICS users
can see, use the ICS examine command or start an ICS match
against yourself.
In ICS mode, changes made to the position by ‘Edit Position’ are
not sent to the ICS: ‘Edit Position’ takes XBoard out of
‘ICS Client’ mode and lets you edit positions locally. If you want to
edit positions on ICS in a way that other ICS users can see, use
the ICS examine command, or start an ICS match against yourself.
(See also the ICS Client topic above.)
<tag-section> ::= <tag-pair> <tag-section>
<empty>
<tag-pair> ::= [ <tag-name> <tag-value> ]
<tag-name> ::= <identifier>
<tag-value> ::= <string>
See the PGN Standard for full details. Here is an example:
[Event "Portoroz Interzonal"]
[Site "Portoroz, Yugoslavia"]
[Date "1958.08.16"]
[Round "8"]
[White "Robert J. Fischer"]
[Black "Bent Larsen"]
[Result "1-0"]
Any characters that do not match this syntax are silently ignored. Note that
the PGN standard requires all games to have at least the seven tags shown
above. Any that you omit will be filled in by XBoard
with ‘?’ (unknown value), or ‘-’ (inapplicable value).
If you select Pause when you are playing against a chess engine and it is not your move, the chess engine's clock will continue to run and it will eventually make a move, at which point both clocks will stop. Since board updates are paused, however, you will not see the move until you exit from Pause mode (or select Forward). This behavior is meant to simulate adjournment with a sealed move.
If you select Pause while you are observing or examining a game on a chess server, you can step backward and forward in the current history of the examined game without affecting the other observers and examiners, and without having your display jump forward to the latest position each time a move is made. Select Pause again to reconnect yourself to the current state of the game on ICS.
If you select ‘Pause’ while you are loading a game, the game stops loading. You can load more moves manually by selecting ‘Forward’, or resume automatic loading by selecting ‘Pause’ again.
In most modes, ‘Backward’ only lets you look back at old positions; it does not retract moves. This is the case if you are playing against a chess engine, playing or observing a game on an ICS, or loading a game. If you select ‘Backward’ in any of these situations, you will not be allowed to make a different move. Use ‘Retract Move’ or ‘Edit Game’ if you want to change past moves.
If you are examining an ICS game, the behavior of ‘Backward’
depends on whether XBoard is in Pause mode. If Pause mode is
off, ‘Backward’ issues the ICS backward command, which backs up
everyone's view of the game and allows you to make a different
move. If Pause mode is on, ‘Backward’ only backs up your local
view.
If you are examining an ICS game, the behavior of Forward
depends on whether XBoard is in Pause mode. If Pause mode is
off, ‘Forward’ issues the ICS forward command, which moves
everyone's view of the game forward along the current line. If
Pause mode is on, ‘Forward’ only moves your local view forward,
and it will not go past the position that the game was in when
you paused.
In most modes, Back to Start only lets you look back at old positions; it does not retract moves. This is the case if you are playing against a local chess engine, playing or observing a game on a chess server, or loading a game. If you select ‘Back to Start’ in any of these situations, you will not be allowed to make different moves. Use ‘Retract Move’ or ‘Edit Game’ if you want to change past moves; or use Reset to start a new game.
If you are examining an ICS game, the behavior of ‘Back to
Start’ depends on whether XBoard is in Pause mode. If Pause mode
is off, ‘Back to Start’ issues the ICS ‘backward 999999’
command, which backs up everyone's view of the game to the start and
allows you to make different moves. If Pause mode is on, ‘Back
to Start’ only backs up your local view.
If you are examining an ICS game, the behavior of ‘Forward to
End’ depends on whether XBoard is in Pause mode. If Pause mode
is off, ‘Forward to End’ issues the ICS ‘forward 999999’
command, which moves everyone's view of the game forward to the end of
the current line. If Pause mode is on, ‘Forward to End’ only moves
your local view forward, and it will not go past the position
that the game was in when you paused.
gnotify
list on ICS, XBoard will automatically observe all of that
player's games, unless you are doing something else (such as
observing or playing a game of your own) when one starts.
The games are displayed
from the point of view of the player on your gnotify list; that is, his
pawns move from the bottom of the window towards the top.
Exceptions: If both players in a game are on your gnotify list, if
your ICS
highlight
variable is set to 0, or if the ICS you are using does not
properly support observing from Black's point of view,
you will see the game from White's point of view.
saveGameFile command-line
option is set, as in that case all games are saved to the specified file.
See Load and Save options.
If you are playing a game on an ICS, the board is always
oriented at the start of the game so that your pawns move from
the bottom of the window towards the top. Otherwise, the starting
orientation is determined by the flipView command line option;
if it is false (the default), White's pawns move from bottom to top
at the start of each game; if it is true, Black's pawns move from
bottom to top. See User interface options.
If you turn on this option when using XBoard with the Internet
Chess Server, you will probably want to give the
set bell 0
command to the ICS, since otherwise the ICS will ring the terminal bell
after every move (not just yours). (The .icsrc file
is a good place for this; see ICS options.)
You can add or remove shortcut keys using the X resources
form.translations. Here is an example of what would go in your
.Xresources file:
XBoard*form.translations: \
Shift<Key>?: AboutGameProc() \n\
<Key>y: AcceptProc() \n\
<Key>n: DeclineProc() \n\
<Key>i: NothingProc()
Binding a key to NothingProc makes it do nothing, thus removing
it as a shortcut key. The XBoard commands that can be bound to keys
are:
AbortProc, AboutGameProc, AboutProc, AcceptProc, AdjournProc,
AlwaysQueenProc, AnalysisModeProc, AnalyzeFileProc,
AnimateDraggingProc, AnimateMovingProc, AutobsProc, AutoflagProc,
AutoflipProc, AutoraiseProc, AutosaveProc, BackwardProc,
BlindfoldProc, BookProc, CallFlagProc, CopyGameProc, CopyPositionProc,
DebugProc, DeclineProc, DrawProc, EditCommentProc, EditGameProc,
EditPositionProc, EditTagsProc, EnterKeyProc, FlashMovesProc,
FlipViewProc, ForwardProc, GetMoveListProc, HighlightLastMoveProc,
HintProc, Iconify, IcsAlarmProc, IcsClientProc, IcsInputBoxProc,
InfoProc, LoadGameProc, LoadNextGameProc, LoadNextPositionProc,
LoadPositionProc, LoadPrevGameProc, LoadPrevPositionProc,
LoadSelectedProc, MachineBlackProc, MachineWhiteProc, MailMoveProc,
ManProc, MoveNowProc, MoveSoundProc, NothingProc, OldSaveStyleProc,
PasteGameProc, PastePositionProc, PauseProc, PeriodicUpdatesProc,
PonderNextMoveProc, PopupExitMessageProc, PopupMoveErrorsProc,
PremoveProc, QuietPlayProc, QuitProc, ReloadCmailMsgProc,
ReloadGameProc, ReloadPositionProc, RematchProc, ResetProc,
ResignProc, RetractMoveProc, RevertProc, SaveGameProc,
SavePositionProc, ShowCoordsProc, ShowGameListProc, ShowThinkingProc,
StopExaminingProc, StopObservingProc, TestLegalityProc, ToEndProc,
ToStartProc, TrainingProc, TruncateGameProc, and TwoMachinesProc.
This section documents the command-line options to XBoard. You can set these options in two ways: by typing them on the shell command line you use to start XBoard, or by setting them as X resources (typically in your .Xresources file). Many of the options cannot be changed while XBoard is running; others set the initial state of items that can be changed with the Options menu.
Most of the options have both a long name and a short name. To turn a boolean option on or off from the command line, either give its long name followed by the value true or false (‘-longOptionName true’), or give just the short name to turn the option on (‘-opt’), or the short name preceded by ‘x’ to turn the option off (‘-xopt’). For options that take strings or numbers as values, you can use the long or short option names interchangeably.
Each option corresponds to an X resource with the same name, so if you like, you can set options in your .Xresources file or in a file named XBoard in your home directory. For options that have two names, the longer one is the name of the corresponding X resource; the short name is not recognized. To turn a boolean option on or off as an X resource, give its long name followed by the value true or false (‘XBoard*longOptionName: true’).
timeControl period.
Default: 5 minutes.
The additional options movesPerSession and timeIncrement
are mutually exclusive.
movesPerSession moves, a
new timeControl period is added to both clocks. Default: 40 moves.
movesPerSession is ignored.
Instead, after each player's move, timeIncrement seconds are
added to his clock.
Use ‘-inc 0’ if you want to require the entire
game to be played in one timeControl period, with no increment.
Default: -1, which specifies movesPerSession mode.
searchTime
is set, the chess engine still keeps track of the clock time and uses it to
determine how fast to make its moves.
showThinking must be on for this option to work. Default: -1 (off).
Not many engines might support this yet!
loadGameFile or loadPositionFile option is set,
XBoard
starts each game with the given opening moves or the given position;
otherwise, the games start with the standard initial chess position.
If the saveGameFile option is set, a move record for the
match is appended to the specified file. If the savePositionFile
option is set, the final position reached in each game of the match is appended
to the specified file. When the match is over, XBoard
displays the match score and exits. Default: 0 (do not run a match).
matchMode to true is equivalent to setting
matchGames to 1.
remoteShell
option described below.)
new
random
Setting this option from the command line is tricky, because you must type in real newline characters, including one at the very end. In most shells you can do this by entering a ‘\’ character followed by a newline. It is easier to set the option from your .Xresources file; in that case you can include the character sequence ‘\n’ in the string, and it will be converted to a newline.
If you change this option, don't remove the ‘new’ command; it is required by all chess engines to start a new game.
You can remove the ‘random’ command if you like; including it causes GNU Chess 4 to randomize its move selection slightly so that it doesn't play the same moves in every game. Even without ‘random’, GNU Chess 4 randomizes its choice of moves from its opening book. Many other chess engines ignore this command entirely and always (or never) randomize.
You can also try adding other commands to the initString; see the
documentation of the chess engine you are using for details.
usePolyglotBook option is set to true,
and the option firstHasOwnBookUCI or secondHasOwnBookUCI applying to the engine
is set to false.
The engine will be kept in force mode as long as the current position is in book,
and XBoard will select the book moves for it. Default "".
chessclub.com.
Another popular chess server to try is freechess.org.
If your site doesn't have a working Internet name server, try
specifying the host address in numeric form.
You may also need
to specify the numeric address when using the icshelper option
with timestamp or timeseal (see below).
-useTelnet -telnetProgram program.
gateway and useTelnet options. The default is
telnet. The telnet program is invoked with the value of
internetChessServerHost as its first argument and the value
of internetChessServerPort as its second argument.
See Firewalls.
telnetProgram on the given host,
instead of using its own internal implementation
of the telnet protocol. You can substitute a different remote shell
program for rsh using the remoteShell option described below.
See Firewalls.
The support for this option in XBoard is minimal. You need to set all communication parameters and tty modes before you enter XBoard.
Use a script something like this:
stty raw -echo 9600 > /dev/tty00
xboard -ics -icscomm /dev/tty00
Here replace ‘/dev/tty00’ with the name of the device that your
modem is connected to. You might have to add several more
options to these stty commands. See the man pages for stty
and tty if you run into problems. Also, on many systems stty
works on its standard input instead of standard output, so you
have to use ‘<’ instead of ‘>’.
If you are using linux, try starting with the script below. Change it as necessary for your installation.
#!/bin/sh -f
# configure modem and fire up XBoard
# configure modem
(
stty 2400 ; stty raw ; stty hupcl ; stty -clocal
stty ignbrk ; stty ignpar ; stty ixon ; stty ixoff
stty -iexten ; stty -echo
) < /dev/modem
xboard -ics -icscomm /dev/modem
After you start XBoard in this way, type whatever commands are
necessary to dial out to your Internet provider and log in.
Then telnet to ICS, using a command like
telnet chessclub.com 5000.
Important: See the paragraph below about extra echoes,
in Limitations.
-icslogon option, inserting some delay between characters
of the logon script may help. This option adds delay
milliseconds of delay between characters. Good values to try
are 100 and 250.
showThinking must be switched on for
this option to work.
Also diverts similar kibitz information of an opponent engine that is playing you
through the ICS to the engine-output window, as if the engine was playing locally.
Each foreground or background argument can be one of the following: black, red, green, yellow, blue, magenta, cyan, white, or default. Here “default” means the default foreground or background color of your xterm. Bold can be 1 or 0. If background is omitted, “default” is assumed; if bold is omitted, 0 is assumed.
Here is an example of how to set the colors in your .Xresources file.
The colors shown here are the default values; you will get
them if you turn -colorize on without specifying your own colors.
xboard*colorizeMessages: true
xboard*colorShout: green
xboard*colorSShout: green, black, 1
xboard*colorChannel1: cyan
xboard*colorChannel: cyan, black, 1
xboard*colorKibitz: magenta, black, 1
xboard*colorTell: yellow, black, 1
xboard*colorChallenge: red, black, 1
xboard*colorRequest: red
xboard*colorSeek: blue
xboard*colorNormal: default
Here is an example of how to set the sounds in your .Xresources file:
xboard*soundShout: shout.wav
xboard*soundSShout: sshout.wav
xboard*soundChannel1: channel1.wav
xboard*soundChannel: channel.wav
xboard*soundKibitz: kibitz.wav
xboard*soundTell: tell.wav
xboard*soundChallenge: challenge.wav
xboard*soundRequest: request.wav
xboard*soundSeek: seek.wav
xboard*soundMove: move.wav
xboard*soundIcsWin: win.wav
xboard*soundIcsLoss: lose.wav
xboard*soundIcsDraw: draw.wav
xboard*soundIcsUnfinished: unfinished.wav
xboard*soundIcsAlarm: alarm.wav
loadGameFile option is set, XBoard loads the specified
game file at startup. The file name - specifies the standard
input. If there is more than one game in the file, XBoard
pops up a menu of the available games, with entries based on their PGN
(Portable Game Notation) tags.
If the loadGameIndex option is set to ‘N’, the menu is suppressed
and the N th game found in the file is loaded immediately.
The menu is also suppressed if matchMode is enabled or if the game file
is a pipe; in these cases the first game in the file is loaded immediately.
Use the pxboard shell script provided with XBoard if you
want to pipe in files containing multiple games and still see the menu.
If the loadGameIndex specifies an index -1, this triggers auto-increment
of the index in matchMode, which means that after every game the
index is incremented by one, causing each game of the match to be played
from the next game in the file. Similarly, specifying an index value of -2
causes the index to be incremented every two games, so that each game
in the file is used twice (with reversed colors).
The rewindIndex option causes the index to be reset to the
first game of the file when it has reached a specified value.
matchMode.
See loadPositionIndex and loadGameIndex.
default: 0 (no rewind).
saveGameFile is set.
loadPositionFile option is set, XBoard loads the
specified position file at startup. The file name - specifies the
standard input. If the loadPositionIndex option is set to N,
the Nth position found in the file is loaded; otherwise the
first position is loaded.
If the loadPositionIndex specifies an index -1, this triggers auto-increment
of the index in matchMode, which means that after every game the
index is incremented by one, causing each game of the match to be played
from the next position in the file. Similarly, specifying an index value of -2
causes the index to be incremented every two games, so that each position
in the file is used twice (with the engines playing opposite colors).
The rewindIndex option causes the index to be reset to the
first position of the file when it has reached a specified value.
You can select other sizes or vary other layout parameters by providing
a list of comma-separated values (with no spaces) as the argument.
You do not need to provide all the values; for any you omit from the
end of the list, defaults are taken from the nearest built-in size.
The value n1 gives the piece size, n2 the width of the
black border
between squares, n3 the desired size for the
clockFont, n4 the desired size for the coordFont,
n5 the desired size for the default font,
n6 the smallLayout flag (0 or 1),
and n7 the tinyLayout flag (0 or 1).
All dimensions are in pixels.
If the border between squares is eliminated (0 width), the various
highlight options will not work, as there is nowhere to draw the highlight.
If smallLayout is 1 and titleInWindow is true,
the window layout is rearranged to make more room for the title.
If tinyLayout is 1, the labels on the menu bar are abbreviated
to one character each and the buttons in the button bar are made narrower.
coordFont option specifies what font to use.
monoMode; XBoard will determine if it is necessary.
flashCount
tells XBoard how many times to flash a piece after it
lands on its destination square.
flashRate
controls the rate of flashing (flashes/sec).
Abbreviations:
flash
sets flashCount to 3.
xflash
sets flashCount to 0.
Defaults: flashCount=0 (no flashing), flashRate=5.
showCoords
is true. If the option value is a pattern that does not specify
the font size, XBoard tries to choose an appropriate font for
the board size being used.
Default: -*-helvetica-bold-r-normal–*-*-*-*-*-*-*-*.
tol pixels
or less from the desired size. A value of -1 will force
a scalable font to always be used if available; a value of 0 will
use a nonscalable font only if it is exactly the right size;
a large value (say 1000) will force a nonscalable font to always be
used if available. Default: 4.
If XBoard is configured and compiled on a system that includes libXpm,
the X pixmap library, the xpm pixmap pieces are compiled in as the
default. A different xpm piece set can be selected at runtime with
the pixmapDirectory option, or a bitmap piece set can be selected
with the bitmapDirectory option.
If XBoard is configured and compiled on a system that does not include
libXpm (or the --disable-xpm option is given to the configure
program), the bitmap pieces are compiled in as the default. It is not
possible to use xpm pieces in this case, but pixmap pieces in another
format called "xim" can be used by giving the pixmapDirectory option.
Or again, a different bitmap piece set can be selected with the
bitmapDirectory option.
Files in the bitmapDirectory must be named as follows:
The first character of a piece bitmap name gives the piece it
represents (‘p’, ‘n’, ‘b’, ‘r’, ‘q’, or ‘k’),
the next characters give the size in pixels, the
following character indicates whether the piece is
solid or outline (‘s’ or ‘o’),
and the extension is ‘.bm’.
For example, a solid 80x80 knight would be named n80s.bm.
The outline bitmaps are used only in monochrome mode.
If bitmap pieces are compiled in and the bitmapDirectory is missing
some files, the compiled in pieces are used instead.
If the bitmapDirectory option is given, it is also possible to replace xboard's icons and menu checkmark, by supplying files named icon_white.bm, icon_black.bm, and checkmark.bm.
For more information about pixmap pieces and how to get additional
sets, see zic2xpm below.
-whitePieceColor #FFFFCC
-blackPieceColor #202020
-lightSquareColor #C8C365
-darkSquareColor #77A26D
-highlightSquareColor #FFFF00
-premoveHighlightColor #FF0000
-lowTimeWarningColor #FF0000
On a grayscale monitor you might prefer:
-whitePieceColor gray100
-blackPieceColor gray0
-lightSquareColor gray80
-darkSquareColor gray60
-highlightSquareColor gray100
-premoveHighlightColor gray70
-lowTimeWarningColor gray70
-firstScoreAbs and -secondScoreAbs if needed.
Default: 0 (no adjudiction)
normal Normal chess
wildcastle Shuffle chess, king can castle from d file
nocastle Shuffle chess, no castling allowed
fischerandom Fischer Random shuffle chess
bughouse Bughouse, ICC/FICS rules
crazyhouse Crazyhouse, ICC/FICS rules
losers Lose all pieces or get mated (ICC wild 17)
suicide Lose all pieces including king (FICS)
giveaway Try to have no legal moves (ICC wild 26)
twokings Weird ICC wild 9
kriegspiel Opponent's pieces are invisible
atomic Capturing piece explodes (ICC wild 27)
3check Win by giving check 3 times (ICC wild 25)
shatranj An ancient precursor of chess (ICC wild 28)
xiangqi Chinese Chess (on a 9x10 board)
shogi Japanese Chess (on a 9x9 board & piece drops)
capablanca Capablanca Chess (10x8 board, with Archbishop
and Chancellor pieces)
gothic similar, with a better initial position
caparandom An FRC-like version of Capablanca Chess (10x8)
janus A game with two Archbishops (10x8 board)
courier Medieval intermedite between shatranj and
modern Chess (on 12x8 board)
falcon Patented 10x8 variant with two Falcon pieces
berolina Pawns capture straight ahead, and move diagonal
cylinder Pieces wrap around the board edge
knightmate King moves as Knight, and vice versa
super Superchess (shuffle variant with 4 exo-pieces)
fairy A catchall variant in which all piece types
known to XBoard can participate (8x8)
unknown Catchall for other unknown variants
In the shuffle variants, XBoard now does shuffle the pieces, although
you can still do it by hand using Edit Position. Some variants are
supported only in ICS mode, including bughouse, and
kriegspiel. The winning/drawing conditions in crazyhouse (offboard
interposition on mate), losers, suicide, giveaway, atomic, and 3check
are not fully understood.
Berolina and cylinder chess can only be played with legality testing off.
In crazyhouse, XBoard now does keep
track of offboard pieces. In shatranj it does implement the baring
rule when mate detection is switched on.
remoteShell. The default is your local user name.
An Internet Chess Server, or ICS, is a place on the
Internet where people can get together to play chess, watch other
people's games, or just chat. You can use either telnet or a
client program like XBoard to connect to the server. There are
thousands of registered users on the different ICS hosts, and it is
not unusual to meet 200 on both chessclub.com and freechess.org.
Most people can just type xboard -ics to start XBoard as an ICS client. Invoking XBoard in this way connects you to the Internet Chess Club (ICC), a commercial ICS. You can log in there as a guest even if you do not have a paid account. To connect to the largest Free ICS (FICS), use the command xboard -ics -icshost freechess.org instead, or substitute a different host name to connect to your favorite ICS. For a full description of command-line options that control the connection to ICS and change the default values of ICS options, see ICS options.
While you are running XBoard as an ICS client, you use the terminal window that you started XBoard from as a place to type in commands and read information that is not available on the chessboard.
The first time you need to use the terminal is to enter your login name
and password, if you are a registered player. (You don't need to do
this manually; the icsLogon option can do it for you.
see ICS options.) If you are not registered,
enter g as your name, and the server will pick a
unique guest name for you.
Some useful ICS commands include
For example help register tells you how to become a registered
ICS player.
If you have more than one pending offer (for example, if more than one player
is challenging you, or if your opponent offers both a draw and to adjourn the
game), you have to supply additional information, by typing something
like accept <player>, accept draw, or draw.
Some special XBoard features are activated when you are in examine mode on ICS. See the descriptions of the menu commands ‘Forward’, ‘Backward’, ‘Pause’, ‘ICS Client’, and ‘Stop Examining’ on the Step Menu, Mode Menu, and Options Menu.
By default, XBoard communicates with an Internet Chess Server by opening a TCP socket directly from the machine it is running on to the ICS. If there is a firewall between your machine and the ICS, this won't work. Here are some recipes for getting around common kinds of firewalls using special options to XBoard. Important: See the paragraph in the below about extra echoes, in Limitations.
Suppose that you can't telnet directly to ICS, but you can telnet to a firewall host, log in, and then telnet from there to ICS. Let's say the firewall is called ‘firewall.example.com’. Set command-line options as follows:
xboard -ics -icshost firewall.example.com -icsport 23
Or in your .Xresources file:
XBoard*internetChessServerHost: firewall.example.com
XBoard*internetChessServerPort: 23
Then when you run XBoard in ICS mode, you will be prompted to log in to the firewall host. This works because port 23 is the standard telnet login service. Do so, then telnet to ICS, using a command like ‘telnet chessclub.com 5000’, or whatever command the firewall provides for telnetting to port 5000.
If your firewall lets you telnet (or rlogin) to remote hosts but doesn't let you telnet to port 5000, you may be able to connect to the chess server on port 23 instead, which is the port the telnet program uses by default. Some chess servers support this (including chessclub.com and freechess.org), while some do not.
If your chess server does not allow connections on port 23 and your firewall does not allow you to connect to other ports, you may be able to connect by hopping through another host outside the firewall that you have an account on. For instance, suppose you have a shell account at ‘foo.edu’. Follow the recipe above, but instead of typing ‘telnet chessclub.com 5000’ to the firewall, type ‘telnet foo.edu’ (or ‘rlogin foo.edu’), log in there, and then type ‘telnet chessclub.com 5000’.
Suppose that you can't telnet directly to ICS, but you can use rsh to run programs on a firewall host, and that host can telnet to ICS. Let's say the firewall is called ‘rsh.example.com’. Set command-line options as follows:
xboard -ics -gateway rsh.example.com -icshost chessclub.com
Or in your .Xresources file:
XBoard*gateway: rsh.example.com
XBoard*internetChessServerHost: chessclub.com
Then when you run XBoard in ICS mode, it will connect to the ICS by using rsh to run the command ‘telnet chessclub.com 5000’ on host ‘rsh.example.com’.
Suppose that you can telnet anywhere you want, but you have to run a special program called ptelnet to do so.
First, we'll consider the easy case, in which ‘ptelnet chessclub.com 5000’ gets you to the chess server. In this case set command line options as follows:
xboard -ics -telnet -telnetProgram ptelnet
Or in your .Xresources file:
XBoard*useTelnet: true
XBoard*telnetProgram: ptelnet
Then when you run XBoard in ICS mode, it will issue the command ‘ptelnet chessclub.com 5000’ to connect to the ICS.
Next, suppose that ‘ptelnet chessclub.com 5000’ doesn't work; that is, your ptelnet program doesn't let you connect to alternative ports. As noted above, your chess server may allow you to connect on port 23 instead. In that case, just add the option ‘-icsport ""’ to the above command, or add ‘XBoard*internetChessServerPort:’ to your .Xresources file. But if your chess server doesn't let you connect on port 23, you will have to find some other host outside the firewall and hop through it. For instance, suppose you have a shell account at ‘foo.edu’. Set command line options as follows:
xboard -ics -telnet -telnetProgram ptelnet -icshost foo.edu -icsport ""
Or in your .Xresources file:
XBoard*useTelnet: true
XBoard*telnetProgram: ptelnet
XBoard*internetChessServerHost: foo.edu
XBoard*internetChessServerPort:
Then when you run XBoard in ICS mode, it will issue the command ‘ptelnet foo.edu’ to connect to your account at ‘foo.edu’. Log in there, then type ‘telnet chessclub.com 5000’.
ICC timestamp and FICS timeseal do not work through some firewalls. You can use them only if your firewall gives a clean TCP connection with a full 8-bit wide path. If your firewall allows you to get out only by running a special telnet program, you can't use timestamp or timeseal across it. But if you have access to a computer just outside your firewall, and you have much lower netlag when talking to that computer than to the ICS, it might be worthwhile running timestamp there. Follow the instructions above for hopping through a host outside the firewall (foo.edu in the example), but run timestamp or timeseal on that host instead of telnet.
Suppose that you have a SOCKS firewall that will give you a clean 8-bit wide TCP connection to the chess server, but only after you authenticate yourself via the SOCKS protocol. In that case, you could make a socksified version of XBoard and run that. If you are using timestamp or timeseal, you will to socksify it, not XBoard; this may be difficult seeing that ICC and FICS do not provide source code for these programs. Socksification is beyond the scope of this document, but see the SOCKS Web site at http://www.socks.permeo.com/. If you are missing SOCKS, try http://www.funbureau.com/.
Game and position files are found in a directory named by the
CHESSDIR environment variable. If this variable is not set, the
current working directory is used. If CHESSDIR is set,
XBoard actually changes its working directory to
$CHESSDIR, so any files written by the chess engine
will be placed there too.
There is no way for two people running copies of XBoard to play each other without going through an Internet Chess Server.
Under some circumstances, your ICS password may be echoed when you log on.
If you are connecting to the ICS by running telnet on an Internet provider or firewall host, you may find that each line you type is echoed back an extra time after you hit <Enter>. If your Internet provider is a Unix system, you can probably turn its echo off by typing stty -echo after you log in, and/or typing <^E><Enter> (Ctrl+E followed by the Enter key) to the telnet program after you have logged into ICS. It is a good idea to do this if you can, because the extra echo can occasionally confuse XBoard's parsing routines.
The game parser recognizes only algebraic notation.
Many of the following points used to be limitations in XBoard 4.2.7 and earlier, but are now fixed: The internal move legality tester in XBoard 4.3.xx does look at the game history, and is fully aware of castling or en-passant-capture rights. It permits castling with the king on the d file because this is possible in some "wild 1" games on ICS. The piece-drop menu does not check piece drops in bughouse to see if you actually hold the piece you are trying to drop. But this way of dropping pieces should be considered an obsolete feature, now that pieces can be dropped by dragging them from the holdings to the board. Anyway, if you would attempt an illegal move when using a chess engine or the ICS, WinBoard will accept the error message that comes back, undo the move, and let you try another. FEN positions saved by XBoard do include correct information about whether castling or en passant are legal, and also handle the 50-move counter. The mate detector does not understand that non-contact mate is not really mate in bughouse. The only problem this causes while playing is minor: a "#" (mate indicator) character will show up after a non-contact mating move in the move list. XBoard will not assume the game is over at that point, not even when the option Detect Mates is on. Edit Game mode always uses the rules of the selected variant, which can be a variant that uses piece drops. You can load and edit games that contain piece drops. The (obsolete) piece menus are not active, but you can perform piece drops by dragging pieces from the holdings. Edit Position mode does not allow you to edit the crazyhouse holdings properly. You cannot drag pieces to the holding, and using the popup menu to put pieces there does not adapt the holding counts and leads to an inconsistent state. Set up crazyhouse positions by loading / pasting a bFEN, from there you can set the holdings. Fischer Random castling is fully understood. You can enter castlings by dragging the King on top of your Rook. You can probably also play Fischer Random successfully on ICS by typing castling moves into the ICS Interaction window.
The menus may not work if your keyboard is in Caps Lock or Num Lock mode. This seems to be a problem with the Athena menu widget, not an XBoard bug.
Also see the ToDo file included with the distribution for many other possible bugs, limitations, and ideas for improvement that have been suggested.
Report bugs and problems with XBoard to <bug-xboard@gnu.org>.
Please use the script program to start a typescript, run XBoard with the ‘-debug’ option, and include the typescript output in your message. Also tell us what kind of machine and what operating system version you are using. The command ‘uname -a’ will often tell you this. Here is a sample of approximately what you should type:
script
uname -a
./configure
make
./xboard -debug
exit
mail bug-xboard@gnu.org
Subject: Your short description of the problem
Your detailed description of the problem
~r typescript
.
The WinBoard / XBoard 4.3 line is being developed by H.G. Muller independently of the GNU Savannah xboard project. Bug reports on this version, and suggestions for improvements and additions, are best posted in the WinBoard forum, WinBoard-development section (http://www.open-aurec.com/wbforum).
If you improve XBoard, please send a message about your changes, and we will get in touch with you about merging them in to the main line of development. Also see our Web site at http://savannah.gnu.org/projects/xboard/.
Tim Mann has been responsible for XBoard versions 1.3 and beyond, and for WinBoard, a port of XBoard to Microsoft Win32 (Windows NT and Windows 95). H.G.Muller is responsible for version 4.3.
Mark Williams contributed the initial (WinBoard-only) implementation of many new features added to both XBoard and WinBoard in version 4.1.0, including copy/paste, premove, icsAlarm, autoFlipView, training mode, auto raise, and blindfold. Ben Nye contributed X copy/paste code for XBoard.
Hugh Fisher added animated piece movement to XBoard, and Henrik Gram
(henrikg@funcom.com) added it to WinBoard. Frank McIngvale added
click/click moving, the Analysis modes, piece flashing, ZIICS import,
and ICS text colorization to XBoard. Jochen Wiedmann ported XBoard to
the Amiga, creating AmyBoard, and converted the documentation to
texinfo. Elmar Bartel contributed the new piece bitmaps introduced in
version 3.2. John Chanak contributed the initial implementation of
ICS mode. The color scheme and the old 80x80 piece bitmaps were taken
from Wayne Christopher's XChess program.
Chris Sears and Dan Sears wrote the original XBoard. They were responsible for versions 1.0 through 1.2.
Evan Welsh wrote CMail. Patrick Surry helped in designing,
testing, and documenting CMail.
Allessandro Scotti added many elements to the user interface of WinBoard, including the board textures and font-based rendering, the evaluation-graph, move-history and engine-output window. He was also responsible for adding the UCI support.
H.G. Muller made WinBoard castling- and e.p.-aware, added variant support with adjustable board sizes, the crazyhouse holdings, and the fairy pieces. In addition he added most of the adjudication options, made WinBoard more robust in dealing with buggy and crashing engines, and extended time control with a time-odds and node-count-based modes. Most of the options that initially wre WinBoard only have now been back-ported to XBoard.
Michel van den Bergh provided the code for reading Polyglot opening books.
Arun Persaud worked with H.G. Muller to combine all the features of the never-released WinBoard 4.2.8 of the Savannah project (mainly by Daniel Mehrmann), and the never-released 4.3.16 into a unified WinBoard 4.4, which is now available both from the Savannah web site and the WinBoard forum.
The cmail program can help you play chess by email with opponents of your choice using XBoard as an interface.
You will usually run cmail without giving any options.
-xv
form also inhibits the cmail introduction message.
$CMAIL_DIR or failing that, $CHESSDIR,
$HOME/Chess or ~/Chess. It will be created if it does not exist.
$CMAIL_ARCDIR or, in its absence, the same
directory as cmail keeps its working files (above).
$CMAIL_MAILPROG or failing that
/usr/ucb/Mail, /usr/ucb/mail or Mail. You will need
to set this variable if none of the above paths fit your system.
$CMAIL_GAMES or failing that
.cmailgames.
$CMAIL_ALIASES or failing
that .cmailaliases.
Type cmail from a shell to start a game as white. After an opening message, you will be prompted for a game name, which is optional—if you simply press <Enter>, the game name will take the form ‘you-VS-opponent’. You will next be prompted for the short name of your opponent. If you haven't played this person before, you will also be prompted for his/her email address. cmail will then invoke XBoard in the background. Make your first move and select ‘Mail Move’ from the ‘File’ menu. See File Menu. If all is well, cmail will mail a copy of the move to your opponent. If you select ‘Exit’ without having selected ‘Mail Move’ then no move will be made.
When you receive a message from an opponent containing a move in one of your games, simply pipe the message through cmail. In some mailers this is as simple as typing | cmail when viewing the message, while in others you may have to save the message to a file and do cmail < file at the command line. In either case cmail will display the game using XBoard. If you didn't exit XBoard when you made your first move then cmail will do its best to use the existing XBoard instead of starting a new one. As before, simply make a move and select ‘Mail Move’ from the ‘File’ menu. See File Menu. cmail will try to use the XBoard that was most recently used to display the current game. This means that many games can be in progress simultaneously, each with its own active XBoard.
If you want to look at the history or explore a variation, go ahead, but you must return to the current position before XBoard will allow you to mail a move. If you edit the game's history you must select ‘Reload Same Game’ from the ‘File’ menu to get back to the original position, then make the move you want and select ‘Mail Move’. As before, if you decide you aren't ready to make a move just yet you can either select ‘Exit’ without sending a move or just leave XBoard running until you are ready.
It is possible to have a cmail message carry more than one game. This feature was implemented to handle IECG (International Email Chess Group) matches, where a match consists of one game as white and one as black, with moves transmitted simultaneously. In case there are more general uses, cmail itself places no limit on the number of black/white games contained in a message; however, XBoard does.
Because XBoard can detect checkmate and stalemate, cmail handles game termination sensibly. As well as resignation, the ‘Action’ menu allows draws to be offered and accepted for cmail games.
For multi-game messages, only unfinished and just-finished games will be included in email messages. When all the games are finished, they are archived in the user's archive directory, and similarly in the opponent's when he or she pipes the final message through cmail. The archive file name includes the date the game was started.
It's possible that a strange conjunction of conditions may occasionally mean that cmail has trouble reactivating an existing XBoard. If this should happen, simply trying it again should work. If not, remove the file that stores the XBoard's PID (game.pid) or use the ‘-xreuse’ option to force cmail to start a new XBoard.
Versions of cmail after 2.16 no longer understand the old file format that XBoard used to use and so cannot be used to correspond with anyone using an older version.
Versions of cmail older than 2.11 do not handle multi-game messages, so multi-game correspondence is not possible with opponents using an older version.
Here are some other programs you can use with XBoard
The GNU Chess engine is available from:
ftp://ftp.gnu.org/gnu/gnuchess/
You can use XBoard to play a game against GNU Chess, or to interface GNU Chess to an ICS.
Fairy-Max is a derivative from the World's smallest Chess program micro-Max, which measures only about 100 lines of source code. The main difference with micro-Max is that Fairy-Max loads its move-generator tables from a file, so that the rules for piece movement can be easily configured to implement unorthodox pieces. Fairy-Max can therefore play a lage number of variants, normal Chess being one of those. In addition it plas Knightmate, Capablanca and Gothic Chess, Shatranj, Courier Chess, Cylinder chess, Berolina Chess, while the user can easily define new variants. It can be obtained from:
http://home.hccnet.nl/h.g.muller/dwnldpage.html
HoiChess is a not-so-very-strong Chess engine, which comes with a derivative HoiXiangqi, able to play Chinese Chess. It can be obtained from the standard Linux repositories through:
sudo apt-get install hoichess
Crafty is a chess engine written by Bob Hyatt. You can use XBoard to play a game against Crafty, hook Crafty up to an ICS, or use Crafty to interactively analyze games and positions for you.
Crafty is a strong, rapidly evolving chess program. This rapid pace of development is good, because it means Crafty is always getting better. This can sometimes cause problems with backwards compatibility, but usually the latest version of Crafty will work well with the latest version of XBoard. Crafty can be obtained from its author's FTP site: ftp://ftp.cis.uab.edu/hyatt/.
To use Crafty with XBoard, give the -fcp and -fd options as follows, where <crafty's directory> is the directory in which you installed Crafty and placed its book and other support files.
The “zic2xpm” program is used to import chess sets from the ZIICS(*) program into XBoard. “zic2xpm” is part of the XBoard distribution. ZIICS is available from:
ftp://ftp.freechess.org/pub/chess/DOS/ziics131.exe
To import ZIICS pieces, do this:
unzip -L ziics131.exe -d ~/ziics
mkdir ~/fritz4
cd ~/fritz4
zic2xpm ~/ziics/fritz4.*
xboard -pixmap ~/fritz4
Alternatively, you can add this line to your .Xresources file:
xboard*pixmapDirectory: ~/fritz4
(*) ZIICS is a separate copyrighted work of Andy McFarland. The “ZIICS pieces” are copyrighted works of their respective creators. Files produced by “zic2xpm” are for PERSONAL USE ONLY and may NOT be redistributed without explicit permission from the original creator(s) of the pieces.
Copyright © 1991 Digital Equipment Corporation, Maynard, Massachusetts.
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When you convey a copy of a covered work, you may at your option remove any additional permissions from that copy, or from any part of it. (Additional permissions may be written to require their own removal in certain cases when you modify the work.) You may place additional permissions on material, added by you to a covered work, for which you have or can give appropriate copyright permission.
Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms:
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Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way.
You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.
You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.
Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License.
An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party's predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.
You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.
A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor's “contributor version”.
A contributor's “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.
Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor's essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.
In the following three paragraphs, a “patent license” is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To “grant” such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party.
If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient's use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.
If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.
A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.
If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.
Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.
The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.
If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Program.
Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and a brief idea of what it does.
Copyright (C) year name of author
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
program Copyright (C) year name of author
This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’.
This is free software, and you are welcome to redistribute it
under certain conditions; type ‘show c’ for details.
The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.
You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see http://www.gnu.org/licenses/.
The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read http://www.gnu.org/philosophy/why-not-lgpl.html.