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Since I upgrade from ubuntu 12.10 to 13.04 I can't change the brightness of the display, it remain in the darkest possible mode. I have a Dell 3721 laptop. Any advice?

@Dell:~$ lspci -nn | grep VGA 
00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)

If I use this, I can change the brigntess, but its so uncomfortable, why I cant use the hotkeys or ubuntu system controll anymore?

echo 3500 | sudo tee /sys/class/backlight/intel_backlight/brightness
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Look at:… – david6 May 22 '13 at 6:08

xbacklight is a command line utility for adjusting brightness and may help you. Install it using the command:

sudo apt-get install xbacklight

and adjust your brightness to using below command:

xbacklight -set percentage brightness

example(for 50% brightness): xbacklight -set 50

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