You will need to be in the folder with the program. As an example, this is how I run it: Code: ./mupen64plus --gfx=plugins/gles2n64.so --nogui /home/user/MyDocs/roms/n64/SuperMario.z64
./mupen64plus --gfx=plugins/gles2n64.so --nogui /home/user/MyDocs/roms/n64/SuperMario.z64