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https://github.com/wez/evremap

A keyboard input remapper for Linux/Wayland systems, written by @wez
https://github.com/wez/evremap

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A keyboard input remapper for Linux/Wayland systems, written by @wez

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# evremap



*A keyboard input remapper for Linux/Wayland systems, written by @wez*



## Why?



I couldn't find a good solution for the following:



* Remap the `CAPSLOCK` key so that it produces `CTRL` when held, but `ESC` if tapped

* Remap N keys to M keys.  Eg: `F3` -> `CTRL+c`, and `ALT+LEFT` to `HOME`



## How?



`evremap` works by grabbing exclusive access to an input device and maintaining

a model of the keys that are pressed.  It then applies your remapping configuration

to produce the effective set of pressed keys and emits appropriate changes to a virtual

output device.



Because `evremap` targets the evdev layer of libinput, its remapping

is effective system-wide: in Wayland, X11 and the linux console.



## Configuration



Here's an example configuration that makes capslock useful:



```toml

# The name of the device to remap.

# Run `sudo evremap list-devices` to see the devices available

# on your system.

device_name = "AT Translated Set 2 keyboard"



# If you have multiple devices with the same name, you can optionally

# specify the `phys` value that is printed by the `list-devices` subcommand

# phys = "usb-0000:07:00.3-2.1.1/input0"



# Configure CAPSLOCK as a Dual Role key.

# Holding it produces LEFTCTRL, but tapping it

# will produce ESC.

# Both `tap` and `hold` can expand to multiple output keys.

[[dual_role]]

input = "KEY_CAPSLOCK"

hold = ["KEY_LEFTCTRL"]

tap = ["KEY_ESC"]

```



You can also express simple remapping entries:



```toml

# This config snippet is useful if your keyboard has an arrow

# cluster, but doesn't have page up, page down, home or end

# keys.  Here we're configuring ALT+arrow to map to those functions.

[[remap]]

input = ["KEY_LEFTALT", "KEY_UP"]

output = ["KEY_PAGEUP"]



[[remap]]

input = ["KEY_LEFTALT", "KEY_DOWN"]

output = ["KEY_PAGEDOWN"]



[[remap]]

input = ["KEY_LEFTALT", "KEY_LEFT"]

output = ["KEY_HOME"]



[[remap]]

input = ["KEY_LEFTALT", "KEY_RIGHT"]

output = ["KEY_END"]

```



When applying remapping configuration, ordering is important:



* Dual Role entries are always processed first

* Remap entries are applied in the order that they appear in

  your configuration file



Here's an example where ordering is important: on the PixelBook Go keyboard,

the function key row has alternate functions on the keycaps.  It is natural

to want the mute button to mute by default, but to emit the F8 key when

holding alt.  We can express that with the following configuration:



```toml

[[remap]]

input = ["KEY_LEFTALT", "KEY_F8"]

# When our `input` is matched, our list of `output` is prevented from

# matching as the `input` of subsequent rules.

output = ["KEY_F8"]



[[remap]]

input = ["KEY_F8"]

output = ["KEY_MUTE"]

```



* How do I list available input devices?

  `sudo evremap list-devices`



* How do I list available key codes?

  `evremap list-keys`



* Is there a GUI for editing the config file?

  Yes, take a look at [Evremap-GUI](https://github.com/M8850/Evremap-GUI)



## Building it



```console

$ sudo dnf install libevdev-devel # redhat/centos

## or

$ sudo apt install libevdev-dev pkg-config # debian/ubuntu



$ cargo build --release

```



## Running it



To run the remapper, invoke it *as root* (so that it can grab exclusive access to the input device):



```console

$ sudo target/release/evremap remap my-config-file.toml

```



Or, grant an unprivileged user access to `evdev` and `uinput`.

On Ubuntu, this can be configured by running the following commands and rebooting:



```

sudo gpasswd -a YOUR_USER input

echo 'KERNEL=="uinput", GROUP="input"' | sudo tee /etc/udev/rules.d/input.rules

```



For some platforms, you might need to create an `input` group first and run:

```

echo 'KERNEL=="event*", NAME="input/%k", MODE="660", GROUP="input"' | sudo tee /etc/udev/rules.d/input.rules

```

as well.



## Systemd



A sample system service unit is included in the repo.  You'll want to adjust the paths to match

your system and then install and enable it:



```console

$ sudo cp evremap.service /usr/lib/systemd/system/

$ sudo systemctl daemon-reload

$ sudo systemctl enable evremap.service

$ sudo systemctl start evremap.service

```



## Runit



If you're using Runit instead of Systemd, follow these steps to create a service.



* Create a directory called `evremap` and create a file called `run` under it

```console

sudo mkdir /etc/sv/evremap

sudo touch /etc/sv/evremap/run

```



* Copy these lines into the run file

```console

#!/bin/sh

set -e 

exec  remap 

```



Replace `` with the path to your evremap executable and `` with the path to your configuration file.



* Finally, symlink the evremap directory to `/var/service`

```console

sudo ln -s /etc/sv/evremap /var/service

```



## OpenRC



To make an OpenRC service, create the file `/etc/init.d/evremap` with the following contents...



```console

#!/usr/bin/openrc-run



supervisor=supervise-daemon

command=""

command_args="remap "

```



Replace `` with the path to your evremap executable and `` with the path to your configuration file.



Make the file executable...



```console

chmod +x /etc/init.d/evremap

```



Enable the service with...



```console

rc-update add evremap

```



Start the service with...



```console

rc-service evremap start

```



## How do I make this execute a command when a key is pressed?



That feature is not implemented.