Support stderrFile

[thomasahle]

• Chess Tuning Tools version: 0.9.3
• Python version: 3.9
• Operating System: Linux

Description

Cutechess-cli supports a json argument "stderrFile" which allows saving any errors output from the engine to a file. This is useful in debugging engines that crash during tuning.

What I Did

I tried to insert "stderrFile" in simple_tune.json like this:

    "engines": [
        {
            "command": "sunfish_lmr.py",
            "fixed_parameters": {},
            "stderrFile": "e1.err"
        },
        {
            "command": "sunfish_lmr.py",
            "fixed_parameters": {},
            "stderrFile": "e2.err"
        }
    ],

I hoped this would be transferred to the engines.json file created by tune, but it doesn't seem to be the case.

[thomasahle]

I tried adding

import sys
sys.stderr = open('error.log', 'a', 0)

at the top of my engine, but it seems to mess with cutechess somehow.