Debian: set Hyper and other keys with Xmodmap

2019-10-10

I wanted to improve the Emacs experience for some awkward key bindings that require you to hold down both Ctrl and Meta. My goal was to create a shortcut for C-M-KEY bindings.

While I could not find a way to simulate that combination by a single key press, I figured I could just use an extra modifier.

Using Super was not an option. I already have that as a shortcut for key sequences such as C-x b that become s-b. So I decided to enable the Hyper key, since my keyboard does not have one by default (standard US QWERTY).

Contents of ~/.Xmodmap

Here is my ~/.Xmodmap in its current form. It is meant to work on my Debian 10 ‘buster’ system—your mileage may vary. The inline comments should offer the guidance you need. In short:

• Use Caps Lock as an extra Control. This disables the default behaviour of locking the letter casing.
• Map Hyper to the right Super (“windows key”). The left Super remains in tact.
• Assign Compose to the Menu key (positioned to the right of Super_R). I use this to type all sorts of useful characters, such as the em dash.

!!!!!!!!!!!!!!!
! Prior notes !
!!!!!!!!!!!!!!!

! These settings have been implemented succesfully on Debian 10
! 'buster' running a variety of desktop environments on top of Xorg.

! To get the current status of the modifiers:
!
!	xmodmap -pm
!
! To find out the key codes that are available:
!
!	xmodmap -pke
!
! Or narrow the results, e.g.:
!
!	xmodmap -pke | grep -E '(Alt|Shift)'
!
! Alternatively, use `xev` to print the key code upon key press.
!
! Here are some of the most likely candidates for changes:
!
!	keycode 37  = Control_L
!	keycode 50  = Shift_L
!	keycode 62  = Shift_R
!	keycode 64  = Alt_L
!	keycode 66  = Caps_Lock
!	keycode 105 = Control_R
!	keycode 133 = Super_L
!	keycode 135 = Menu

!!!!!!!!!!!!!!!!!
! Modifications !
!!!!!!!!!!!!!!!!!

! Clear the modifiers concerned
clear lock
clear mod3
clear mod4

! Set Caps Lock as an extra Ctrl
keycode 66 = Control_L

! Set the Right Super as Hyper
keycode 134 = Hyper_R

!!! OR Set the Right Alt as Hyper
!! keycode 108 = Hyper_R

! Set the Menu key as Compose
keycode 135 = Multi_key

! Add/update the modifiers
add control = Control_L

! Add a new Hyper_R modifier and move Hyper_L from mod4 to mod3
add mod3 = Hyper_L Hyper_R
add mod4 = Super_L Super_R

Create that file and then load it with xmodmap ~/.Xmodmap.

Sample of Emacs keys using Hyper

Everything works as expected on my end. I can now inspect the functions that Emacs calls when pressing C-M-KEY (do that with C-h k followed by the key press you are interested in).

For example, here is a set of aliases. These do not change the defaults. They just provide additional means of accomplishing the same task (so replace the initial H with C-M to view the original keys).

(use-package lisp
  :bind (("H-f" . forward-sexp)
		 ("H-b" . backward-sexp)
		 ("H-n" . forward-list)
		 ("H-p" . backward-list)
		 ("H-a" . beginning-of-defun)
		 ("H-e" . end-of-defun)
		 ("H-h" . mark-defun)
		 ("H-d" . narrow-to-defun)
		 ("H-k" . kill-sexp)
		 ("H-K" . backward-kill-sexp)
		 ("H-[" . insert-pair)
		 ("H-]" . delete-pair)
		 ("H-SPC" . mark-sexp)))

I have yet to find a way to simulate C-M- by just pressing H- without having to define each key binding individually. For example, I would like to have something like:

(setq (x-ctrl-keysym x-meta-keysym) 'hyper)  ; Not valid elisp

With that, Hyper would not be a real modifier. It would rather be the same as holding down Ctrl+Alt at the same time. Will continue exploring this and update this article accordingly.