Finally Stable Caps to Ctrl Mapping

Over the years, I have tried so many ways on Linux to map Caps Lock to Ctrl:

• Xorg config (that didn't work on a tty console)
• Inputrc (really weird rules that depended on initial state)
• Gnome keyboard config

Finally there is a stable way to remap Caps Lock to Ctrl.  It is relatively simple and it is at the lowest level in Linux.

Thanks to this page for all the details: https://wiki.archlinux.org/index.php/Map_scancodes_to_keycodes but it took a lot of effort to parse out what actually needed to be done.

Here is a distilled version:

0) Make sure Caps Lock is OFF

1) Create the following file:

/etc/udev/hwdb.d/10-caps-modifier.hwdb

---

evdev:atkbd:dmi:*            # built-in keyboard: match all AT keyboards for now

  KEYBOARD_KEY_3a=leftctrl   # bind capslock to leftctrl

2) Run  the following command:

$ systemd-hwdb update

3) Run the following command to make the remapping take immediate effect:

$ udevadm trigger

This was tested on Ubuntu 18.04.2 LTS running Xfce.  The remapping works great in tty consoles, and the X input system.