Python CGOS Client

This client connects Go programs that implement the GTP protocol to the Computer Go Server (CGOS). If you downloaded this, you know what they are. Any GTP engine is supported, not just those written in Python.


This is version 0.3.0. This program is ©2009 Christian Nentwich and is licensed to you under the terms of the GNU General Public License version 3 (GPLv3).

Please read the change log.

For the avoidance of doubt: this licence makes no claim whatsoever about the Go programs used with this client, in particular any programs using this client to connect to CGOS shall not meet the definition of a "covered work", or derivative work, under this license.

The CGOS server and TCL client are © Don Daily and others and are not included here.


Features in common with standard CGOS TCL client:

Additional features:

Features not yet supported:


Developed on Python 2.6, no extensions required. It may work on Python 2.5, but that is not tested. If you are using Windows, get the package from here, it's a good standalone installer. You will have to provide a configuration file. See sample.cfg for an example, or see below. Run the client using:
# Windows
C:\Python26\Python bin\ config.cfg

# Unix		
python bin/ config.cfg
To kill the client, please place a "kill file" in the location you specified in the configuration file. You may of course kill the process, too, but the kill file will ensure that you will finish the current game and log off nicely. After the engine quits, the kill file will be deleted.

Note: If a kill file is put in place, the client will quit ASAP if it is not currently in a game. In practice, this means when the next status message is received by the server, usually within a minute.

GTP Commands

Playing engines need the following GTP commands: If the time commands are missing, no time control instructions will be passed to the engine. Further notes:

GTP Extensions

The following GTP extensions are available. If your engine records its own logs, or writes its own SGF records with analysis information in them, you may find them useful.

CommandWhen CalledMeaning
cgos-opponent_name Between boardsize and first move Gives the name of the opponent engine (the CGOS login name)
cgos-gameover After two passes, resignation or illegal move Final result as reported by the server. Will be in format required by SGF RE property, meaning:
  • B+{score} or W+{score}, e.g. B+0.5, or
  • B+Resign or W+Resign, or
  • B+Time or W+Time, or
  • B+Forfeit or W+Forfeit


The client will produce the following log files at debug level - standard output stream logging is at info level or higher only: All of these log files are set up as rolling files that be renamed engine.log.1, and so on, when they get beyond 2MB. A maximum of 5 rolling log files is kept.

Displaying Games Using GoGUI

The Python CGOS client can stream the GTP command stream to a secondary engine called an "observer" engine. It is up to you how you use this, for example:

First, download GoGUI from Next, make sure you use gogui-display as an observer in your configuration file, like so in Windows:

    CommandLine = C:\Program Files\Java\jdk1.6.0_13\bin\java.exe -jar C:\path\to\gogui-1.1.9\lib\gogui-display.jar
Please do not use javaw.exe, stick with java.exe, or the input stream to gogui-display will be cut off. In Linux:
    CommandLine = /usr/bin/java -jar /path/to/gogui-1.1.9/lib/gogui-display.jar
Either way, please note that if you close the GoGUI window, the client will think the observer engine crashed and terminate your connection. You will then have to restart to resume your game. If you wish to stop displaying, put a kill file in place (see above), then start the client again without an observer.

Alternating Between Multiple Engines

In the configuration file, each GTP engine has an attribute called NumberOfGames. This attribute is mandatory in this version of the client, even if there is only one engine, though in the case of one engine it is ignored. Multiple GTP engines are played sequentially in a round-robin fashion. For example, if NumberOfGames is set to 2 for EngineA and to 3 for EngineB, the client will play the engines as follows:



Sample Configuration

This sample configuration shows how GNU Go can be connected to play on CGOS, 9x9 board size, and with GoGUI running locally to view all games. In addition, the client will play round-robin between two engine configurations, running the engine at level 8 for 5 games, followed by level 10 for 2 games, and then starting over.

  KillFile = kill.txt
  # Name to display on console / in logs
  Name = Gnugo Level 8
  CommandLine = gnugo.exe --mode gtp --score aftermath --capture-all-dead --chinese-rules --level 8
  ServerHost =
  ServerPort = 6867
  ServerUser = myuser
  ServerPassword = mypw
  # Switch to next engine after this many games
  NumberOfGames = 5
  # Optional: persist games here
  SGFDirectory = ..\sgf9x9
  Name = Gnugo Level 10
  CommandLine = gnugo.exe --mode gtp --score aftermath --capture-all-dead --chinese-rules --level 10
  ServerHost =
  ServerPort = 6867
  ServerUser = myuser-level10
  ServerPassword = mypw-level10
  # Switch back to first engine after this many games
  NumberOfGames = 2
  # Optional: persist games here
  SGFDirectory = ..\sgf9x9
# Observer engine (e.g. GoGUI)
  CommandLine = C:\Program Files\Java\jdk1.6.0_13\bin\java.exe -jar C:\path\to\gogui-1.1.9\lib\gogui-display.jar