Last night I tried removing the change directory command by just giving a path to the emulator directly. That failed because the emulator seems to look in the current working directory for a core library (which obviously wasn’t there since I removed the cd command).

There is a –corelib option on mupen64plus which allows you to specify a path to the core library. I also tried that (with the path implied by the previous error). That also did not work, although I could not diagnose why because it had changed the display settings in the interim to make the console output tiny.

I hope this is all helping someone with more skills than me.