evdevremapkeys

evdevremapkeys

A daemon to remap key events on linux input devices

Motivation

The remapping of input key events is an problem, and one that has been solved at many levels over the years. On a traditional X11 desktop, the usual way to do this is with xbindkeys; it's simple and effective and you shouldn't try and write something different.

However, with the shift to Wayland, we have a problem. Wayland obviously isn't X11 so any X11 based remapping utility isn't going to work. Wayland compositors typically use libinput to manage input events, but while libinput supports remapping conceptually, it does not expose any mechanism to configure it. This is left as an exercise to the compositor and neither Weston nor Mutter expose remapping.

So where does this leave us? If we are to provide a remapping mechanism that is not dependent on the compositor, it must run below libinput, which means it must work with the linux input subsystem. And so, here we are.

Technical approach

There's only one real sane approach to doing event remapping at the input subsystem level: Read events from physical input devices, and then generate new input events on a virtual device managed through uinput.

One legitimate question is whether the virtual device attempts to fully replicate the original physical device, just with remapped events, or whether it's a dedicate device that only emits the new events which leaving the physical device free to send events directly to other clients.

Depending on your exact use-case, you might be able to leave the original physical device as-is, but for me, it turned out that I had to swallow the original events because they will be picked up by libinput and then trigger actions in my desktop environment.

To avoid this, you have to take a grab on the physical device, so no other client receives events, and then forward all un-modified events through your virtual device. It's annoying but unavoidable - you can't hide individual events from other clients.

Software Setup

Install from PyPI

The recommended way to install the program is to use pipx.

$ pipx install evdevremapkeys

You can also use pip, but on modern distros, pipx is a far better experience.

Create a configuration

You will need to create an initial configuration file for the program to be able to run and doing anything useful.

It's recommended to start from one of the example config files and adapt it for your hardware and the remapping you need.

Place your final file at: ~/.config/evdevremapkeys/config.yml

Run the program

evdevremapkeys

More details

See RUNNING.md for more details.