I am using some UCI engines from a command prompt. Most work fine (i.e. Stockfish, Houdini, Komodo) but when I use e.g. SOS (ver.5.1) or Hermann (Ver.2.8), I cannot seem to type any more moves after move 23. For example:

position startpos moves f2f4 g8f6 e2e3 d7d5 g1f3 g7g6 c2c4 f8g7 b1c3 c7c5 c4d5 f6d5 d1b3 d5c3 b2c3 e8g8 f1e2 d8c7 e1g1 c8e6 e2c4 e6c4 b3c4 b8d7 c1a3 a8b8 d2d4 b7b5 c4b3 a7a5 a1d1 c5c4 b3b1 d7f6 d1e1 f6d5 b1e4 f8d8 a3c5 d5c3 e4e7 c7e7 c5e7 d8d5 a2a3 b8e8

After b8e8, I just cannot type any more moves. Tried this on different computers running different O/S's.

  • Can you clarify cannot type any more moves? Are you literally unable to insert new characters to the command or if you add more moves do you get an error? If you actually can't insert new characters, then it's not a limit of the command you're executing but of the terminal you're using
    – mowwwalker
    Nov 20, 2020 at 20:11

1 Answer 1


I suspect this is due to the length of the command; the one in your question is 254 characters long, close to 28 = 256 which might be a maximum command length for some engines.

I do not know a solution for this, but it seems possible to use the position command with a FEN string, for example as used in this question.

  • Thanks. Yes, it looks that way doesn't it? It's actually around 250 characters. I know of the alternative by sending the position in FEN format, thanks for mentioning it. When you play the engine under a GUI, e.g. Arena, and observe the engine log with F4, it does not have this input restriction. I guess it interfaces differently under a windowed application vs a command prompt.
    – John
    Nov 20, 2020 at 18:31
  • around 250 characters is probably still close enough to possibly run into issues- I'm guessing with the windowed application it does some tricks (maybe just keeps feeding in the new FENs)
    – pulsar512b
    Nov 20, 2020 at 23:34

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