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A program to read and control device brightness
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Branch: master
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xdbob and Hummer12007 Make the use of `SetBrightness` dynamic
It will only be used if the user do not have the permission to directly
write to the backlight device.

Signed-off-by: Antoine Damhet <>
Latest commit 53a906b Sep 10, 2019


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).


The program is available in:

  • Arch Linux
  • Void Linux
  • Debian - starting with Buster (and derivatives)
  • Ubuntu - starting with 18.04 (and derivatives)
  • openSUSE - available in Tumbleweed, use OBS utilities/brightnessctl devel project for Leap < 15.1
  • Fedora/EPEL (orphaned, deleted since F30, maintainer wanted)

One can build and install the program using make install. Consult the Makefile for relevant build-time options.


Modifying brightness requires write permissions for device files or systemd support. brightnessctl accomplishes this (without using sudo/su/etc.) by either of the following means:

  1. installing relevant udev rules to add permissions to backlight class devices for users in video and leds for users in input. (done by default)

  2. installing brightnessctl as a suid binary.

  3. using the systemd-logind API.

The behavior is controlled by the INSTALL_UDEV_RULES flag (setting it to 1 installs the udev rules, it is the default value).

The systemd support (since v243) is controlled by the ENABLE_SYSTEMD flag (in that case it is recommended to set INSTALL_UDEV_RULES to 0).


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

  -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.
  -n, --min-value		set minimum brightness, defaults to 1.
  -e, --exponent[=K]		changes percentage curve to exponential.
  -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 (can be a wildcard).
  -c, --class=CLASS		specify device class.
  -V, --version			print version and exit.

  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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