xbacklight man page
xbacklight — 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.
Print out the program version 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.