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I have a Sony E Series laptop with Fedora 17 and Windows 8 in dual boot. The brightness adjusts just fine on my Windows8 but not in Fedora. If I change it with the brightness slider in the power settings nothing happens. The brightness stays maximum even if I adjust the slider to minimum.

Blinded by my screen and frustrated by the draining battery I tried everything on the net.

I tried things like -

  1. Reinstall bash. yum reinstall bash
  2. Add this to kernel parameters in grub2.cfg - acpi_backlight=vendor
  3. Add this line to xorg.conf - Option "RegistryDwords" "EnableBrightnessControl=1"
  4. Add this line to grub.cfg - "video.brightness_switch_enabled=1"
  5. Update the drivers for your video card.
  6. Install some utility. Example - xbacklight utility from freedesktop.org

None of these suggestions worked for me.

Kshitiz Sharma
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1 Answers1

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Issue the command - echo 500 > /sys/class/backlight/intel_backlight/brightness

Replace 500 with a number of your choice.

Don't take a number below 100 as that may (and probably will) turn off your screen.

Just take multiples of 100 from 500 (which is a reasonable low) to 4000 (this max may be different depending on your laptop model).

You'll need root access to execute this command.

Kshitiz Sharma
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  • Does this work in Lubuntu 11.10? I'd tried but the file contains the same value, 4882. Should I reboot the system? – Sigur Sep 01 '12 at 23:30
  • I have these 2 folders: `acpi_video0 intel_backlight` – Sigur Sep 01 '12 at 23:37
  • @Sigur What does it say when you try to change the value? You need to issue that command as root user. Type `su` at the terminal and enter the root password. – Kshitiz Sharma Sep 02 '12 at 02:57
  • Well, nothing happens. I am using `sudo echo ....` and after the password, nothing wrong. No errors. but when I use `cat /sys/....` to check the value, it is the same, 4882. – Sigur Sep 02 '12 at 14:39
  • Hello. I found the answer. Using `sudo` does not work. But with `sudo su` first to change to root and then... aha! It works! Thanks. – Sigur Sep 02 '12 at 18:58
  • This command is not being saving after reboot. How to fix this? I don't want to execute this every time. – Sigur Sep 04 '12 at 00:30
  • @Sigur You can put that command in a startup script. That way the command will automatically run every time you start the system. – Kshitiz Sharma Sep 05 '12 at 15:06
  • Thanks. I did something like this, discussed here http://unix.stackexchange.com/questions/47183/script-with-root-permission – Sigur Sep 05 '12 at 18:45