xbacklight

Get the current screen brightness as a percentage

$ xbacklight

Set the screen brightness to 40%

$ xbacklight -set [40]

Increase current brightness by 25%

$ xbacklight -inc [25]

Decrease current brightness by 75%

$ xbacklight -dec [75]

Increase backlight to 100%, over 60 seconds (value given in ms), using 60 steps

$ xbacklight -set [100] -time [60000] -steps [60]

xbacklight [-help] [-display display] [-get] [-set percent] [-inc percent] [-dec percent]

Xbacklight is used to adjust the backlight brightness where supported. It finds all outputs on the X server supporting backlight brightness control and changes them all in the same way.

-get

Print out the current backlight brightness of each output with such a control. The brightness is represented as a percentage of the maximum brightness supported.

-set percent

Sets each backlight brightness to the specified level.

-inc percent

Increases brightness by the specified amount.

-dec percent

Decreases brightness by the specified amount.

-help

Print out a summary of the usage and exit.

-time milliseconds

Length of time to spend fading the backlight between old and new value. Default is 200.

-steps number

Number of steps to take while fading. Default is 20.

Keith Packard, Open Source Technology Center, Intel Corporation.

Xrandr(3)