A minimal backlight control daemon for Linux.

• Set brightness using blctl set [OPTIONS] <LEVEL>
• Increase brightness using blctl increase [OPTIONS] <AMOUNT>
• Decrease brightness using blctl decrease [OPTIONS] <AMOUNT>
• Get brightness using blctl get [OPTIONS]
• Get raw maximum brightness using blctl get-max
• Optionally use raw backlight device driver values using --from-raw and --to-raw

Using blctl is simple thanks to its easy-to-use command-line interface.

To list all commands and their options, run blctl --help and blctl [COMMAND] --help in your terminal.

By default, most commands take as input and print as a result to stdout a value between 0-100 inclusive. If an error is encountered, blctl will print the error to stderr and exit with a non-zero exit code.

The function to map arbitrary backlight brightness levels to a 0-100 inclusive range is lossy in precision. If losslessness is required, use the --from-raw and --to-raw flags to specify brightness and print results in the arbitrary brightness range defined by your backlight device driver rather than the more portable but lossy mapped range.

While only a NixOS flake is provided, blctl should in theory work on any Linux distribution with Sysfs support. For distributions other than NixOS, manual packaging is required. Systemd and Runit service configurations can be found in the ./service-configs/ directory of this repository.

After adding this repository as a flake, blctl can be installed either by specifying the package in your directly, or by using the module provided by the flake.

Internally, blctl is written only in safe Rust with no reliance on any non-Rust dependencies. It uses Sysfs to communicate with the backlight device driver using simple file reads and writes, and uses a Unix domain socket for inter-process communication between the command-line interface (blctl) and the daemon (blctld).

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.