how to change the right control key in a super/hyper modifier in emacs

Question

I'd like to change the right control key along into a "super" modifier and right alt key into the "alt" modifier (not the Meta) in Solaris and Linux (as I know how to do that in Windows using AutoHotKey). I know how to do this:

(define-key local-function-key-map (kbd "<rwindow>") 'event-apply-super-modifier

But I don't know how to specify the right control key or right alt key (which are more convenient to type than the Windows keys). If that can be done straight in emacs (and avoid AutoHotKey in Windows as well) that would be great. Otherwise I'd like to know what can achieve in Solaris and Linux the same think that AutoHotKey does.

Answer 1

I don't know of any way to do this in Emacs. As far as I know, the two Ctrl keys are treated the same. For some OSes, there's an option to change the keysym for R-Alt but I don't know of one for X Windows. Note that you can use the x-alt-keysym variable to change the keysym for both Alt keys.

You can change the modifiers bound to each key in X Windows using xmodmap. The Arch Wiki article covers its use. Basically:

• Type xmodmap -pm to print a list of modifiers and the keys assigned to them, eg.

      shift       Shift_L (0x32),  Shift_R (0x3e)
      lock
      control     Control_L (0x42),  Control_R (0x69)
      mod1        Alt_L (0x40),  Alt_R (0x6c),  Meta_L (0xcd)
      mod4        Super_L (0x85),  Super_R (0x86) ....
  

• Then create a file that clears and rebinds the modifiers you want to change. Eg. to change R-Ctrl to super, this should work:

      clear super
      add super = Super_L Super_R Control_R
      clear control
      add control = Control_L
  

• To handle, the Alt keys, you could use:

      clear meta
      add meta = Alt_L
  

  That should cause Emacs to find the existing meta modifier and stop treating the Alt keys as meta by default. Then the R-Alt key will be available as an alt modifier for use in Emacs (and the L-Alt as meta). I've never tried this.

  If that doesn't work, you'll have to pick an unused modifier to bind R-Alt to, eg. hyper. Then you could use that in Emacs bindings.

• You can activate the changes saving your file as ~/.Xmodmap and running

  xmodmap ~/.Xmodmap
  

  In many desktop environment, ~/.Xmodmap will be automatically run at startup. If not, you'll have to run it in your ~/.xinitrc file:

  if [ -s ~/.Xmodmap ]; then
      xmodmap ~/.Xmodmap
  fi