brillo - control the brightness of backlight and keyboard LED devices


Cameron Nemo OCTOBER 2018


brillo - control the brightness of backlight and keyboard LED devices


brillo [operation [value]] [-k] [-q|-r] [-m|-c] [-e|-s ctrl] [-u usecs] [-v loglevel]


brillo is a tool for controlling the brightness of backlight and LED devices on Linux. Notable features include:

Automatic best controller detection

Smooth transitions and exponential (natural) adjustments

Ability to save and restore brightness across boots

Directly using sysfs to set brightness without relying on X

Unprivileged access with no new setuid binaries

Containment with AppArmor



-G: Get brightness value (default)

-S VALUE: Set brightness to value

-A VALUE: Increment brightness by given value

-U VALUE: Decrement brightness by given value

-O: Store the current brightness

-I: Restore cached brightness

-L: List available devices

-H: Show a short help output

-V: Report the version


The default controller is automatically selected to maximize precision. To select every controller available, use the -e option. To select a specific controller, use the -s option.

-a: Automatic controller selection (default)

-e: Operate on every controller available

-s CONTROLLER: Manual controller selection

The list operation (-L) can be used to discover available controllers.


By default, brillo acts on the display devices, but the -k option can be used to adjust keyboard backlights instead. In either case, it may be necessary to specify an alternative controller.

-l: Act on display backlight (default)

-k: Act on keyboard backlight and LEDs


By default, brillo acts on the brightness property. With these options, the maximum brightness of a controller can be retrieved. In addition, it is possible to set (or retrieve) a minimum cap, which is used to prevent lowering the brightness beyond a certain threshold. This is especially useful for devices that become pitch black when the brightness is set to 0.

-b: Current brightness (default)

-m: Maximum brightness

-c: Minimum brightness

Value modes

Values may be given, or presented, in percent or raw mode.

The default value mode is linear percentages, however the -q option can be used for exponential percentages. Exponential mode offers a more natural and gradual brightness scale.

Raw mode will use the same format and range given by the device driver; this mode is most useful when a high degree of precision is required, such as for keyboard controllers.

-p: Linear percentages (default)

-q: Exponential percentages

-r: Raw values

Smooth adjustment

brillo is capable of gradually adjusting the brightness over a specified time period. Use the -u microseconds option to specify how long the operation should take. This flag is silently ignored when not setting the brightness.

-u microseconds: time used to space the operation out


By default, brillo outputs only warnings or more severe messages. To enable more verbose logs on stderr, use the verbosity argument: -v loglevel. The loglevel is a value between 0 and 8 (corresponding to syslog severities).


Get the current brightness in percent:

brillo [-G]

Increase brightness by 5 percent:

brillo -A 5

Specify the controller to use:

brillo -s intel_backlight -A 5

Set the brightness to 50% for every controller:

brillo -e -S 50

Retrieve or increase the brightness using an exponential scale:

brillo -q
brillo -q -A 5

Decrease the brightness and smooth the operation over 1500 microseconds:

brillo -u 150000 -U 5

Get the raw maximum brightness value:

brillo -rm

Set the minimum cap for the acpi_video0 controller to a raw value of 2:

brillo -rc -s acpi_video0 -S 2

Note: subsequent attempts to set the controller’s brightness to a raw value less than 2 will then be raised to this minimum threshold.

List keyboard controllers:

brillo -Lk

Activate a specific controller LED:

brillo -k -s "input15::scrolllock" -S 100

Note: LEDs often only take 0 or 1 in raw value (i.e. for off/on). In these cases, you can use any non-zero value instead of 100.


Copyright (C) 2018-2019 Cameron Nemo, 2014 Fredrik Haikarainen

This is free software, see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE |