Chdb is a port of the chess database browser from the 2nd edition of plan9 dated around 1995. Unfortunately the browser was removed from the subsequent editions of the system. Recently i found an old iso image of the 2nd edition at http://9.postnix.pw/hist/2e/ and decided to port the software to Plan 9 from user space (aka plan9port).
UPDATE 21-03-2021: The Plan9 Foundation released all editions of plan9 under the MIT license.
To build chdb you need to have plan9port properly installed with the PLAN9 environment variable pointing to the installation directory. Then
git clone https://github.com/anastasop/chdb
cd chdb
mk all
It consists of two programs. The first o.cdb reads files in text format and generates a database. You can try it with ./o.cdb games/*. The resulting m.out is included in the repo for convenience. The second program o.ddb is the database browser. Run ./o.ddb m.out and the browser will start. You should see a window like the following:
The manual is in doc/ in pdf and text formats. Also online at
The 2nd edition release of chdb was only a prototype and was abandonded later. Compared to modern databases it is not as feature rich but it has some very interesting points especially for programmers to study.
- A parser for a game format similar to PGN. Supports both textual and binary formats. Check games/ for examples.
- A DSL based on regular expressions for querying the database.
- A graphical board game editor.
- A chessboard move generator and verifier.
- Vector graphics. Pieces are not resizable bitmaps but are drawn with vector graphics and then rendered. An approach similar to SVG.
- An interesting UI where the squares, the rows and the files of the chessboard drive the interaction with the browser.
Chdb was written by Ken Thompson for the first and second editions of plan9. Ken is most famous as the creator of UNIX by he is also one of the pioneers of chess programming. He co-created Belle, a former chess computer world champion and created the first endgame databases for up to six-pieces.
This is based on plan9 code with is released under the MIT license.
Copyright 2021 Plan 9 Foundation
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
The port to plan9port is also released under the MIT license.
Copyright 2021 Spyros Anastasopoulos
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.