Strong chess program for GNU/Linux with a command line interface? I'm looking for a strong chess program for GNU/Linux with a command line interface, or one that I can alter to make it suit my needs

After a quick search, I found the question Chess program for Linux/Unix console, which gives some programs that are either too slow or too weak (with no command line though, it was on terminal, but that is easily manageable).
I wrote about Stockfish in the link you had. I don't see there is any engine better than that.