CapsLock to Ctrl and Esc

One essential part of my workflow is remapping the Caps Lock key to act as Ctrl when held and Esc when tapped. It’s always one of the very first things I set up whenever I get a new computer.

I’m so used to it that whenever I help someone with tech issues and have to use their computer, I start stumbling over basic tasks—and I can almost tell they begin to doubt if I’m actually good with computers.

On Windows, I use AutoHotKey with this script¹.

On macOS, I use Karabiner-Elements with this complex modification².

On Linux, my setup has changed a few times. For my current NixOS configuration, I use Interception Tools with the caps2esc plugin.

To set it up like I did, add this to your /etc/nixos/configuration.nix:

{ config, pkgs, ... }:
let
  udevmonConfigFile = pkgs.writeText "udevmon.yaml" ''
SHELL: [${pkgs.runtimeShell}, -c]
---
- JOB: "${pkgs.interception-tools}/bin/intercept -g $DEVNODE | ${pkgs.interception-tools-plugins.caps2esc}/bin/caps2esc -m 1 | ${pkgs.interception-tools}/bin/uinput -d $DEVNODE"
  DEVICE:
    EVENTS:
      EV_KEY: [KEY_CAPSLOCK, KEY_ESC, KEY_LEFTCTRL]
  '';
in
{
  # ...
  systemd.services.udevmon = {
    description = "Interception Tools - udevmon";
    wantedBy = [ "multi-user.target" ];
    serviceConfig.ExecStart = "${pkgs.interception-tools}/bin/udevmon -c ${udevmonConfigFile}";
  };
}

This configuration applies the change system-wide. I chose to configure it in configuration.nix rather than home-manager because udevmon needs to run as root to work correctly.