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I have Stockfish compiled on my machine. Instead of just running the Stockfish program in the terminal, is it possible to interact with it in a separate program?

For example, some basic things I might want to do:

  • Create a position object from a FEN.
  • Get an evaluation from the position object (limiting with depth or time).
  • Return an array of positions for all the legal moves from the position.

These are just some very basic examples. Can anyone supply some code snippets for these instructions? I'm really struggling to find any helpful documentation.

EDIT: It looks like this really has a two part solution. The first is piping the input/output to some external program. The second is understanding the UCI protocol to perform what I want to do. Does anyone know the UCI protocol for getting all of the possible moves/positions from a given position? Also, it looks like the 'eval' command only gives a static evaluation of a position (i.e. no consideration of the future). Is there anyway to retrieve a time/depth based evaluation as well?

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I think you're talking about how to fork a process for the engine and how to use it for the UCI protocol.

What you need to do is:

  1. Fork a new child process for the Stockfish engine
  2. Send and receive UCI commands to/from the engine
  3. Parse the UCI commands yourself

Do you want to study existing source code? Look at:

http://talkchess.com/forum/viewtopic.php?t=57770

Download Chess Game Analyzer, it's a simple Python script for automatic annotation.

When you have the source code, look at the the following:

 p = subprocess.Popen(engineName, stdin=subprocess.PIPE,
                     stdout=subprocess.PIPE,
                     stderr=subprocess.STDOUT)

This line creates a new process for the engine, where engineName is the path of the engine executive.

p.stdin.write("uci\n")

This line sends the uci command to the engine.

for eline in iter(p.stdout.readline, '')

This line parses a UCI response.

  • How do you view the source code? It looks like you can only get the .rar from that download link. Is there a git repository somewhere for viewing the source code? – Dan Oct 23 '16 at 5:22
  • @Dan Download the archive and extract it. You'll find a Python script file. It's not on Github. – SmallChess Oct 23 '16 at 5:23
  • I'm sorry I know this is really basic, but how do you view the contents. Every program I download to extract, it keeps generating a .exe file. None of them will actually show me the contents. Are there any extraction programs for the mac that will actually allow me to view the files? – Dan Oct 23 '16 at 5:31
  • @Dan you will need a RAR file extractor. RAR is a compression technique like ZIP. Google where to download the extractor. – SmallChess Oct 23 '16 at 5:32
  • I've tried two different extractors (one called Unarchiver and one called Extractor). Both only generate .exe files. Are there any programs that actually let me view the source code? – Dan Oct 23 '16 at 5:35
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As for the first part, I have been using Perl and the IPC::Open2 package successfully for running Stockfish programmatically. http://perldoc.perl.org/IPC/Open2.html

As for the UCI way to "get all possible moves", you need to set the "multiPV" parameter to some large value (99?), causing the engine to calculate and report a value for every possible move.

As for making the engine calculate (and report), you use the "go" command.

Try it first interactively from the console to get an idea of what the output looks like, so you can intelligently parse it with your program.

  • I agree that I need to become more comfortable with the commands in the console first. When I try the "go" command, it looks like the output just gives the best move (not the actual evaluation number). "eval" at least gives the number but it's only static (doesn't consider future moves). – Dan Oct 25 '16 at 23:31
  • The evaluations for multiPV are given in info lines -- the "score cp" value (centipawns) or "score mate" if the engine finds forced mate. – Jeff Y Oct 26 '16 at 10:10
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Can anyone supply some code snippets for these instructions? I'm really struggling to find any helpful documentation.

Since you say you need to manipulate chess data structures programmatically, you might find the kind of specific programming guidance you want at the Chess Programming Wiki.

It links to the Universal Chess Interface standard, which Stockfish uses to interface to the chess GUI or other program you're using/writing.

  • Note that there is no comment associated with the single "unuseful" flag given to this answer. This is consistent with behavior in response to most of my answers, suggesting that one individual is neg flagging me wholesale, i.e. I seem to have a personal troll. What should we call him? – jaxter Oct 23 '16 at 19:44

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