Slight

Smooth Light - Backlight and LED devices control for Linux.

This is essentially a reimplimentation of brightnessctl and light. So why does it exist?

TL;DR: Minimize the amount of scripting you have to do when integrating with other programs or services.

The two utilities (brightnessctl and light) only perform very basic functions. They can increment and decrement (or set) brightness levels of devices in /sys/class/backlight and /sys/class/leds. That's great, and wonderful how simple and straightforward they are, however if you want to do anything more complicated you'll need to write wrappers in another language (usually shell code) to take care of that.

Considering that actually using the sysfs ABIs for changing device brightness is so simple, you may as well just do it with your own scripts. Slight exists so that you don't have to reinvent the wheel anymore.

Advantages

• Interpolate brightness adjustments over a duration of time
• Conditionally adjust brightness only if it is currently above or below the target.
• Direct integration with other programs (such as Gammastep or Redshift, with hooks).
• Control brightness external monitors with DDC/CI.
• Control multiple devices at the same time, so that one command affects multiple.
• Define custom percentage curves so that brightness does not adjust linearly, but rather according to your eye's perception.

Installation

If you package this program for any distributions, please add it below!

Generic Linux

Assuming you have Rust installed, with $HOME/.cargo/bin added to your environment's PATH:

$ cargo install slight

Note:

The binary will need to be run with sudo unless you install the requisite udev rules. These can be found in backlight-90.rules in the root of the repository.

Your user must also be added to the video group to satisfy these rules.

Copy backlight-90.rules to /etc/udev/rules.d, and add your user to the video group.

$ curl https://raw.githubusercontent.com/spikespaz/slight/master/90-backlight.rules -o 90-backlight.rules
$ sudo install -Dm444 90-backlight.rules -t /etc/udev/rules.d
$ sudo usermod -aG video $USER

NixOS

Note:

Don't forget to install the udev rules!

This can be done via the NixOS option services.udev.extraRules or services.udev.packages.

For example, in your system configuration:

{
  environment.systemPackages = [pkgs.slight];
  services.udev.packages = [pkgs.slight];
  users.users.YOURNAME.extraGroups = ["video"];
}

With Flakes

Below is an example showing how to use the overlay, so that you can use the package from pkgs.slight throughout your Nix configurations.

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";

    slight.url = "github:spikespaz/slight";
    slight.follows = "nixpkgs";
  };

  outputs = inputs @ {
    self,
    nixpkgs,
    ...
  }: let
    system = "x86_64-linux";

    pkgs = import nixpkgs {
      inherit system;
      overlays = [
        inputs.slight.overlays.default
      ];
    };
  in {
    # ...
  };
}