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.
Tried:
- '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.
61 Answer
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.
