I'm using elementary OS Freya installed as a dual boot. Since installing everything was okay. Suddenly, the screen is very dark. With my F-keys I can not control the brightness. If I use my big screen (HDMI) all is okay. I've a Packard Bell EasyNote LS Laptop.

Intel Core i7-2670QM | AMD Radeon HD 7670M, 1 GB VRam

  • 2
    Perhaps take a look here? askubuntu.com/questions/149054/… – Gabriel Jul 14 '15 at 16:16
  • Just an idea, but laptop might be having problems with battery and decreasing screen's brigthness is system's energy-saving plan? Otherwise I see no logical explanation in system dropping brightness to the ground. – V_Pavel Jul 14 '15 at 18:58
  • It will most likely be helpful if you can disclose your graphics card. – Lewis Goddard Jul 14 '15 at 19:59
  • Does anybody know if you can make keyboard shortcuts for brightness adjustments? – user3790 Jan 17 '16 at 11:01

Proper way to do it should be via System Settings -> Power -> Display brightness

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  • Doesen't work for me... Nothing happens. – celsheet Jul 16 '15 at 7:16
  • Lars, in that case it looks like a problem with acpi or video drivers. – V_Pavel Jul 16 '15 at 7:20
  • What should I do now? Update my driver? – celsheet Jul 16 '15 at 7:22
  • give it a try. download latest version from amd website, reboot, try to change brightness again – V_Pavel Jul 16 '15 at 7:23
  • I updated my driver. Nothing has changed. – celsheet Jul 17 '15 at 18:46

I've fix the problem: I had to change my brightness in Windows. Now all is normal. Thanks for the help.


I had the same problem where my function keys suddenly stopped working with brightness levels. For me the fix was simple:

echo manual | sudo tee /etc/init/brightness.override

Restart machine


Try xbacklight.

Its simple to control the screen brightness according to your needs through TUI.

Syntax is simple:

xbacklight n

where n is the percentage with which you want to increase or decrease the screen brightness.


xbacklight -3

decreases the screen brightness by 3%

and similarly,

xbacklight +3 # Do not omit the + sign…

increases the screen brightness by 3%

Another way could be:

echo 600 > /sys/class/backlight/*backlight/backlight

You can change 600 with the brightness level you want. Higher number means more brightness.

Run this as a super user or alternatively, do

chmod 665 /sys/class/backlight/*_backlight/backlight

first and then run the above command.

Hope you found it useful.


I just tested this. It works.

cd /sys/class/backlight/*/

sudo chmod 777 ./brightness

sudo echo $(cat max_brightness) > ./brightness

  • Could you explain what those commands do? – Gabriel Jul 14 '15 at 18:59
  • 2
    Change directory into the backlight folder. Change the file permissions for the brightness file to full read/write/execute for all users and groups, and then 'copy' the maximum brightness into the current brightness file. I could explain it in more technical detail if you want, but this is the gist of it. – TW80000 Jul 14 '15 at 19:22
  • I have two folders in /sys/class/backlight/, this only affects the first one. – Lewis Goddard Jul 14 '15 at 20:00
  • Well one of them muse be for you screen. Does it work on either of them? – kagronick Jul 15 '15 at 0:22
  • Nope, although I know this is related to my graphics card, not the permissions. – Lewis Goddard Jul 15 '15 at 11:59

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