How to edit the GRUB file

Question

The backlight of my Acer Aspire 5336 screen turns off when Ubuntu 12.04 is installed. I found that it could be corrected by editing the GRUB file Screen turns black after booting, backlight only works in recovery mode on an Acer Aspire 5736z

But since I cannot do so via Ubuntu (as the backlight is turned off) how can I edit the GRUB file?

Thank you

possible duplicate of [How do I get permissions to edit system configuration files?](http://askubuntu.com/questions/92379/how-do-i-get-permissions-to-edit-system-configuration-files) — David Foerster, Dec 21 '13 at 18:15
I think not. I cannot do anything from Ubuntu OS because the screen is black! I'm looking for a way to do so from Windows — Sach, Dec 21 '13 at 18:19
Does Ctrl+Alt+F1 bring you to a terminal? Try to login in there with your credentials and use `nano` to edit files. You can also edit GRUB menuentries from within GRUB. — LiveWireBT, Dec 23 '13 at 08:12

score 2 · Answer 1 · answered Dec 21 '13 at 18:20

2

Why don't you try to edit the file using a external monitor?

Because if you can't edit the file and update Grub with the actual installation, you have to bind the installed OS using a LiveCD or LiveUSB (http://howtoubuntu.org/how-to-repair-restore-reinstall-grub-2-with-a-ubuntu-live-cd) and then edit the /etc/default/grub and update Grub.

answered Dec 21 '13 at 18:20

Leo

It sort of worked! You still have to adjust the brightness using the keyboard and in my case it is decreasing the brightness that worked!! – Sach Dec 29 '13 at 17:52

Marcus · Accepted Answer · 2013-12-23T10:00:48.113

1

You could boot to a live CD and edit GRUB that way, or you can do it whilst in GRUB itself, much faster:

Highlight "Ubuntu" in the GRUB menu, but rather than hitting Return to boot Ubuntu, hit the letter e. This will take you to an editor.

If you never see a list of operating systems to boot, holding Shift as the computer loads will display it.

Add acpi_osi=Linux acpi_backlight=vendor at the end of the second-to-last line, as shown in the picture:

See the second-to-last line.

Hit F10, which will boot Ubuntu, backlight and all.
You can then make the change permanent by following the instructions in the answer you referred to.

edited Dec 23 '13 at 10:00

answered Dec 21 '13 at 18:35

Marcus

thank you.. but can u tell me whats meant by "quiet splash" in second bullet point – Sach Dec 21 '13 at 20:04
It didn't work for me – Sach Dec 22 '13 at 05:21
So I've updated my answer to make it hopefully a little more clear. "Quiet splash" are two boot options, one shows the Ubuntu splash screen ("Ubuntu" with the loading dots, I think) and one prevents the terminal gubbins from being shown as Ubuntu loads. It makes the boot process look a little smoother, rather than having reams of commands flying up the screen which most people don't care about. – Marcus Dec 22 '13 at 09:15

2 Answers2