So,in may laptop with Ubuntu 12.04, the startup is like this:

1) I see the Ubuntu logo with the 5 dots on a purple background for a few seconds.

2) The screen goes completely black (no back light), but it's not shut down, i can still see shadows.

3) The system is fully loaded (i can log-in), but the screen is still shadowy (no back light).

4) I have to wait about 1 minute (logged or not) for the back light to turn on.

How do I prevent the system from shutting the back light at startup ?


Open a Terminal window (Ctrl+Alt+T) and run this command to open GRUB's main configuration file in nano (a non-graphical text editor):

sudo nano /etc/default/grub

In the text editor, find this line:


Add acpi_backlight=vendor to the end, so it looks like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Save the file and quit the text editor, by pressing Ctrl+o followed by Ctrl+x. Then run:

sudo update-grub

Done. Backlight will be at full strength by default.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.