Ubuntu: Change brightness works in Unity but not spectrwm


I use spectrwm so I want to be able to adjust the screen brightness using command line tools. However, none seem to be working. The odd thing is that if I run Unity and access the "Brightness" settings through the normal UI, the brightness correctly changes.


  • 'xbacklight -get' returns nothing.
  • 'xbacklight -set' does nothing.
  • 'xrandr -brightness' changes the contrast, but not the brightness.

I am using a Toshiba Tecra P5, running Ubuntu 14.04.


My installation was a fresh install, thus it used a lot of default settings in the setup.

Accessed the "Additional Drivers" window:

$ software-properties-gtk --open-tab=4

My graphics card (G86M Quadro NVS 130M) was using the open source Nouveau driver by default. Selected the recommended Nvidia binary driver (version 340.76 from nvidia-340 (proprietary, tested)), clicked on Apply Changes then restarted my laptop.

It now works!

xbacklight -get returns the current brightness percentage and xbacklight -set correctly adjust the brightness! This works both when running Unity or when using spectrwm.

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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