Escape Meta Alt Control Shift

Rock climbing, guitar playing, ivory tickling, and GNU Emacs are all inextricable parts of my life. And all of them demand far too much of my left pinky. After slightly straining my left wrist on a crimpy dynamic slab, I have become acutely aware of the punishing ritual I subject my weakest finger to, from dawn till dusk.

Emacs pinky is an undeniable issue amongst programmers. I already alleviate stress by using evil-mode, remapping Caps Lock to Escape, and raising my wrists above the keyboard by shoving a sweater underneath my arms. However, I still expect my left pinky to auto-complete with Tab, return to command mode with Caps Lock (masquerading as Escape), capitalise letters with Shift, change buffers (and run countless other Emacs commands) with Control, switch windows via sway with Super (aka Meta or the Windows key), and, of course, press Alt to help summon the genie <M-x>.

I should surely be able to find some method to further reduce my poor digit’s burden.

Space as a leading key?

Doom Emacs and Spacemacs eschew Control in favour of Space for commands. The briefest of flirtations with Doom has convinced me for life that there is nothing as perverse as using another human’s Emacs config. After restoring my ~/.emacs.d/ and sanity, I found no easy way to extricate the leading space behaviour from either Doom and Spacemacs.

I delved further into abandoned forums to seek a more viable (and less deviant) option.

Caps as Escape and Control?

caps2esc showed promise. It remaps not only Caps Lock to Escape, but also allows Caps Lock to act as Control whilst it is held down. space2meta remaps Space to Meta (aka Super) whilst it is held down. And both run on the udev level so they are window manager agnostic and work in TTY!

I started copy-pasting code and creating my own caps2meta, return2meta, and space2ctrl, until I thought there must be an even better solution. And, indeed, there is.

Dual Function Keys

Dual Function Keys allows anybody to remap any key to any other key when it is tapped, double-tapped or held down.

To install on Arch Linux, simply:

sudo pacman -S interception-dual-function-keys

Then create a YAML file describing the key remappings required. In my personal config: Caps Lock becomes Escape when tapped, and Meta / Super when held; Space becomes Ctrl when held; Enter / Return becomes Meta / Super when held.

~/.config/dfk.yaml

TIMING:
    TAP_MILLISEC: 200
    DOUBLE_TAP_MILLISEC: 150

MAPPINGS:
    - KEY: KEY_CAPSLOCK
      TAP: KEY_ESC
      HOLD: KEY_LEFTMETA

    - KEY: KEY_SPACE
      TAP: KEY_SPACE
      HOLD: KEY_LEFTCTRL

    - KEY: KEY_ENTER
      TAP: KEY_ENTER
      HOLD: KEY_LEFTMETA

Create a YAML file in /etc/interception/udevmon.d/ for the system configuration.

/etc/interception/udevmon.d/keys.yaml

- JOB: intercept -g $DEVNODE | dual-function-keys -c /path/to/dfk.yaml | uinput -d $DEVNODE
  DEVICE:
    EVENTS:
      EV_KEY: [KEY_CAPSLOCK, KEY_SPACE, KEY_ENTER]

Now to get the keybindings up and running:

sudo udevmon

To have the keybindings start automatically at boot-time:

sudo systemctl enable udevmon
sudo systemctl start udevmon

Addendum

Et voilà! My thumb and right pinky can now relieve my left pinky of most of its duties. And I’ll soon be back on the wall, cursing crimpy dynamic slabs.

UPDATE

To only set dual-function-keys on for one user, and leave the keyboard unchanged for other users, use uswitch. Install uswitch via the AUR and edit the below configuration file.