So I'm trying to create a combination of keys to generate ISO keys for the Portuguese layout, the key in question is the , pressing it will normally generate the  character,  + Shift  will generate the >  character. So I'm trying to create a combination using xmodmap , and I want this to work for all the programs. I've been searching on Google and came up with this  example for Control  + P  = Up : xmodmap -e "keycode 33 = p P Up" keycode 33  matches p , so where does Control  come up in that command? What I want is: map Control  + ,  to > map Control  + .  to