{"id":4376,"date":"2021-08-23T10:00:00","date_gmt":"2021-08-23T15:00:00","guid":{"rendered":"https:\/\/www.foell.org\/justin\/?p=4376"},"modified":"2023-04-17T10:08:48","modified_gmt":"2023-04-17T15:08:48","slug":"remapping-keyboard-keys-in-ubuntu-with-udev-evdev","status":"publish","type":"post","link":"https:\/\/www.foell.org\/justin\/remapping-keyboard-keys-in-ubuntu-with-udev-evdev\/","title":{"rendered":"Remapping Keyboard Keys in Ubuntu with udev \/ evdev"},"content":{"rendered":"\n

A coworker gave a lunch and learn about mechanical keyboards. I should have known it would be an entrance to a black hole… it all started 25 years ago with my beloved Zeos Keyboard with Alps keygates<\/a> – which I consequently wrecked after spilling a beer into it \ud83c\udf7a Then onto my HHKB Lite2<\/a> which I still have but need a host of adapters to connect its PS\/2 connector<\/a>. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Now I’m entering the modern mechanical era with a Keychron K6<\/a> – a 65% keyboard that closely resembles my HHKB layout. It has Gateron Blue (light and clicky) switches that remind me of my famed Zeos board. Here’s the original layout:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

My first issue is I have a bit of OCD when it comes to pairing. I expect insert\/del, home\/end, and page up\/down to be at least near each other, if not next to each other. So I changed the keycaps in the far right row, around the corner to the FN1\/2 keys. I used low(ish) profile DSA keys<\/a> on this edge to mimic the lower arrow keys from the HHKB. Also I got custom colored beige\/blue FN1\/FN2 keys<\/a> to quickly remind me that FN1 is for the gold functions and FN2 is for blue.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Now I needed to change what the swapped keys did when I pressed them…<\/p>\n\n\n\n\n\n\n\n

When it comes to customizing<\/span> keyboards in Linux, there are at least 10 ways to skin this cat \ud83d\ude3c but for a one-to-one replacement, evdev is the answer. Why? Because it’s low-level enough to work with everything, whether you use Xorg or Wayland. It even works in the console<\/a>.<\/p>\n\n\n\n

Getting information about your keyboard<\/h2>\n\n\n\n

For our research you’ll probably need to install a couple of things:<\/p>\n\n\n\n

sudo apt install evtest evemu-tools<\/code><\/pre>\n\n\n\n
You can use evemu-describe<\/code> to get information about your keyboard. If you run evemu-describe<\/code> without any arguments, you’ll be prompted to select the input device. I’ve highlighted my input in bold<\/strong>.<\/p>\n\n\n\n
$ sudo evemu-describe<\/strong>\nAvailable devices:\n\/dev\/input\/event0:\tLid Switch\n...\n\/dev\/input\/event19:\tGeneric USB Audio\n\/dev\/input\/event20:\tKeychron K6 Keyboard\n\/dev\/input\/event21:\tKeychron K6 Consumer Control\n\/dev\/input\/event22:\tKeychron K6 System Control\n\/dev\/input\/event23:\tBluetoothMouse3600 Mouse\n\/dev\/input\/event24:\tBluetoothMouse3600 Consumer Control\nSelect the device event number [0-24]: 20<\/strong>\n# EVEMU 1.3\n# Kernel: 5.11.0-27-generic\n# DMI: dmi:bvnDellInc.:bvr1.7.0:bd10\/22\/2020:br1.7:svnDellInc.:pnXPS137390:pvr:rvnDellInc.:rn0G2D0W:rvrA00:cvnDellInc.:ct10:cvr:\n# Input device name: \"Keychron K6 Keyboard\"\n# Input device ID: bus 0x05 vendor 0x5ac product 0x24f version 0x11b\n# Supported events:\n#   Event type 0 (EV_SYN)\n#     Event code 0 (SYN_REPORT)\n...\n#     Event code 15 (SYN_MAX)\n#   Event type 1 (EV_KEY)\n#     Event code 1 (KEY_ESC)\n...\n# Properties:\nN: Keychron K6 Keyboard\nI: 0005 05ac 024f 011b\n...<\/code><\/pre>\n\n\n\n
Take note of the properties line towards the bottom:
I: 0005 05ac 024f 011b<\/code>
It is the Bus\/Product\/Vendor\/Version identifier that we’ll use that to identify the keyboard in our hardware DB file.<\/p>\n\n\n\n
Gather Keycode & Scancode Information<\/h2>\n\n\n\n
Along with the Bus\/Product\/Vendor\/Version identifier, you’ll need scancodes and keycodes for our configuration file.<\/p>\n\n\n\n
The keys I wanted to replace on the far right are:<\/p>\n\n\n\n