Ubuntu – How to control Brightness


I didn't install anything myself, but only Ubuntu 12.04 LTS on an Acer 4741g.

I use Fn+left/right to change the brightness, but failed.

How can I control the brightness levels?

Best Answer

Try this:

  1. Open a terminal (Ctrl + Alt + T).
  2. Then type sudo nano /etc/default/grub. It will ask for your password. Type it in.
  3. Around the 11th line, there will be something like: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash". Change it to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
  4. Save the file by Ctrl+O followed by Ctrl+X. Then run sudo update-grub in the terminal.
  5. Reboot and see if backlight adjustment works. If not, undo the changes you did above, by invoking the text editor as in steps 1 and 2.

Hope it helps.

Works for Acer Aspire v3-571,Acer Aspire v3 571g,Hewlett Packard Bell EasyNote TS,Acer Aspire 4755G,Acer Aspire 5750-6866, Acer Aspire 5739, Lenovo T540p