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# 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:
i, info get device info.
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%
```
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