How to remap Ctrl to Caps Lock in a TTY?

Question

I already understand how to remap keys in an X graphical server. However, I sometimes like to do work from a TTY and cannot seem to figure out a way to functionally remap Ctrl to Caps Lock.

I have already tried creating a .keymap file with the following contents:

keycode 37 = Control_L

Then sourcing it using loadkeys, but to no avail.

However, 37 is the keycode for Ctrl in X (according to xmodmap -pke | grep 'Control') so perhaps the keycode is different in a TTY? If so, how would I go about determining the correct key code and subsequently setting the remap?

Answer 1

The answer above by porkfreezer is great! To make this a permanent solution, you could make a .settings directory, or use your .local directory, to create your own keymap file like you were trying to do, that can be used when logging into a TTY. To do this, I recommend copying the keyboard keymap you are currently useing (for me it's us.map.gz) to your home directory that you chose above, for me this looks like

cp /usr/share/kbd/keymaps/i386/qwerty/us.map.gz ~/.settings/

Then you can unzip and edit that file to contain the key mapping you want. For me I have switched the Escape key and Caps_Lock, for use with vim. Then create a symlink to this file to a directory where Linux can find it, like so:

sudo ln -s ~/.settings/custom.map /usr/share/kbd/keymaps/i386/qwerty/custom.map

Now, when in a TTY, you can run sudo loadkeys custom to load the key mapping. To have this as the default, you could create a

/etc/vconsole.conf

file containing the line

KEYMAP=custom

Then edit your /etc/mkinitcpio.conf file (you will need superuser privileges) by adding keymap to the end of the hooks list, this should look something like the following

...
HOOKS=(base udev autodetect modconf block filesystems keyboard fsck keymap)
...

Then run

sudo mkinitcpio -p linux

And that's it! After a reboot, whenever you log into a TTY, your custom keymap will be used.

Hopfully this helps!

Answer 2

Kernel keycodes are different than X keycodes. Key 37 for the kernel is actually K (on qwerty). To find kernel keycodes you can use showkey:

$ showkey
kb mode was UNICODE
[ if you are using this under X, it might not work
since the X server is also reading /dev/console ]

press any key (program terminates 10s after last keypress)...
keycode  28 release    # I released enter
keycode  29 press      # I pressed control
keycode  29 release    # I released control
keycode  58 press      # I pressed caps lock
keycode  58 release    # I released caps lock

So, to map Ctrl to Caps Lock:

keycode 29 = Caps_Lock

Or Caps Lock to Ctrl:

keycode 58 = Control