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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.

crimsonspectre
  • 649
  • In the terminal, what does dpkg --get-selections | egrep xbacklightreturn for you ? – Cbhihe Aug 09 '15 at 16:03
  • It returns 'xbacklight install'. – crimsonspectre Aug 09 '15 at 18:46
  • You have an Nvidia Quadro NVS 130M graphics unit on that apparently. Just like you my box runs on an Intel Core 2 Duo T9300. Unlike you I have an NVIDIA Quadro FX 570M chip and in my case xbacklight -get does not produce any result either. Just tried. The problem is well known and has also affected KDE desktops until version 4.10.1 included. It was later fixed in KDE. Apparently this is not the case for Gnome desktops. It is not clear what the problem is. I would suggest going to the developers' page and reporting. Good luck ! – Cbhihe Aug 09 '15 at 19:47
  • .. alternatively go to a hardware support forum to discuss this. – Cbhihe Aug 09 '15 at 19:51
  • Is this an issue with Gnome, xbacklight or the laptop itself? You said it was fixed in KDE, but wouldn't xbacklight and xrandr be window manager agnostic? I can change the backlight brightness, but only when using the Unity UI, not the command line tools. – crimsonspectre Aug 10 '15 at 06:01
  • You use spectrwm... on top of Unity 7.2.5 ? Did you recently upgrade yr Nvidia graphics driver.? Do you use graphics acceleration ? Try turning that off if it is the case. If you don't get any result from that, try this solution by Rogier Mulders: http://askubuntu.com/questions/162317/screen-brightness-not-working. There is a lot you can look at on line, including on AU. This has either to do with Nvidia drivers or with X11 implementation in conjunction with Nvidia and xbacklight. HTH. Let us know and good luck. – Cbhihe Aug 10 '15 at 09:46

1 Answers1

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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.

crimsonspectre
  • 649