# brightnessctl

This program allows you read and control device brightness. Devices, by default, include backlight and LEDs (searched for in corresponding classes). If omitted, the first found device is selected.

It can also preserve current brightness before applying the operation (allowing for usecases like disabling backlight on lid close).

## Installation

The program is available in:
* [Fedora/EPEL](https://apps.fedoraproject.org/packages/brightnessctl)
* [Arch Linux (AUR)](https://aur.archlinux.org/packages/brightnessctl)

## Permissions

Modifying brightness requires write permissions for device files. This can be accomplished (without using sudo/su/etc.) by either of the following means:

1) installing brightnessctl as a suid binary (done by default)

2) adding a similar udev rule (assuming your user is in `video` group for backlight and `input` group for leds):
```
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="leds", RUN+="/bin/chgrp input /sys/class/leds/%k/brightness"
ACTION=="add", SUBSYSTEM=="leds", RUN+="/bin/chmod g+w /sys/class/leds/%k/brightness"
```

## Usage
```
Usage: brightnessctl [options] [operation] [value]

Options:
  -l, --list			list devices with available brightness controls.
  -q, --quiet			suppress output.
  -p, --pretend			do not perform write operations.
  -m, --machine-readable	produce machine-readable output.
  -s, --save			save previous state in a temporary file.
  -r, --restore			restore previous saved state.
  -h, --help			print this help.
  -d, --device=DEVICE		specify device name.
  -c, --class=CLASS		specify device class.

Operations:
  g, get			get current brightness of the device.
  m, max			get maximum brightness of the device.
  s, set VALUE			set brightness of the device.

Valid values:
  specific value		Example: 500
  percentage value		Example: 50%
  specific delta		Example: 50- or +10
  percentage delta		Example: 50%- or +10%
 ```