xbacklight(1) adjust backlight brightness using RandR extension


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.
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.
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.