It would be nice if there was a polyglot.ini file with the default settings for fruit2.3.1!
Is it correct that the default options will be used if I don't specify any engine specific options? I currently use this sample polylgot.ini file for the Linux version:
I don't have Polyglot, nor Linux yet, however this looks very much like the default I've seen in CA and Fritz GUI's, except I don't know if the book option in your setup instructs the use of just book.bin, or varied (varied is not default, as you probably know).