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I am struggling with screen brightness reset issues . It resets to 100% on every reboot. I have tried searching for solutions but none of them worked[including xbacklight ].

Since I can change screen brightness by pressing Fn + F3 a couple of times , I was wondering if I could make a script do it on every reboot?

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Alternative way

Writing a script to press a key combination to set your screen's brightness seems a bit of a detour to me. You can directly set your screen brightness on log in by adding the command:

xrandr --output <your_screenname> --brightness 0.7

to your startup applications. Of course, instead of 0.7 (=70%), you can use any value you prefer.

Replace <your_screenname> by the actual name of your screen. Find out your screen's name by looking into the output of the command:

xrandr

Look for the word connected; the name before that is your screen's name

Add the command to your startup applications

Open Startup Applications (Dash > Startup Applications) and choose "Add". Add the command above and next time you log in, your screen's brightness will be set automaically to the value you defined in the command.

  • Thanks for your answer , it did change the brightness but the colors got slightly wierd. I mean , in the settings the brightness was still set to 100% and the brightness of the cursor was distinctly brighter than the rest of the screen. I was looking for a proper reduction of screen brightness. Anyway , your answer provided me some relief. – yask Oct 26 '14 at 8:02
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The brightness of an Ubuntu system is maintained as numbers in 3 files brightness, max_brightness and actual_brightness in /sys/class/backlight/<VGA>directory.

Replace <VGA> with intel_backlight if you are having an Intel VGA card and radeon_bl0 if you are having an AMD card.

You may check the value in the max_brightness file and based on that, set a value in the brightness file. So when the system reboots, the brightness actually resets to the value in the brightness file.

You won't be needing a custom script to reset brightness.

  • Unfortunately I am using AMD APU 8400 Card – yask Oct 26 '14 at 7:58
  • what are the contents of /sys/class/backlight directory in your system? – astrob0t Oct 26 '14 at 8:01
  • It contains a directory named radeon_bl0 which itself contains following actual_brightness brightness max_brightness subsystem uevent bl_power device power type – yask Oct 26 '14 at 8:04
  • good. Then you may follow my instructions to manipulate the brightness files in the radeon_bl0 folder. – astrob0t Oct 26 '14 at 8:05
  • The max value is 253 and in brightness folder it is already 63. But on restart I guess it resets! Should I try changing the value in max_brighntess instead? – yask Oct 26 '14 at 8:06

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