Grub can't be saved after modification

Question

I have Ubuntu 14.04 32 bit machine on my lenovo g580. Default brightness keys are not working and can't decrease brightness in settings also. The brightness has been fixed at maximum. I followed few similar questions and modified grub document in /etc/default/grub, but I'm not being able to save this file after modification. Even though I have logged in as admin.It shows "You do not have the necessary permission to save the file", when I tried "save as" in the same location with the same name. What should I do to decrease brightness? Please help.

possible duplicate of How do I get permissions to edit system configuration files? — David Foerster, Mar 13 '15 at 15:29

score 1 · Answer 1 · edited Mar 13 '15 at 15:17

1

Add a simple line : quiet splash acpi_backlight=vendor to grub

gksudo gedit /etc/default/grub
Replace GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
with GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset acpi_backlight=vendor"
sudo update-grub && sudo reboot

It worked on:

Ubuntu 12.04 LTS (Asus U31SD-XH51 )
Ubuntu 14.04 LTS (Dell 14z)
Ubuntu 14.04 LTS (Lenovo g500, remove nomodeset and it will work fine)

You could try adding a line to /etc/rc.local that will set the desired brightness level. To edit the file, run gksudo gedit /etc/rc.local and add following line:

echo X > /sys/class/backlight/intel_backlight/brightness

Substitute the X by the desired brightness level.

edited Mar 13 '15 at 15:17

karel

114,770

answered Mar 13 '15 at 14:55

kevy

668

I did all the things you specified. But still not working. Downloaded an app called "Brightness Controller". Even that is not working. And i don't have rc.local in the above given location. I found that in /etc/rc2.d/S99rc.local . But not getting where should I add the code that you have given. And thanks for helping. – Subrahmanya Sriram Mar 14 '15 at 14:59
Have you tried sudo apt-get update; sudo apt-get upgrade? – kevy Mar 14 '15 at 15:59
Yeah I had.. Now I'm using Windows 7, thinking of switching back to Ubuntu.. – Subrahmanya Sriram May 11 '15 at 13:12

score 0 · Accepted Answer · edited Aug 05 '16 at 23:06

0

Try this:

Open the Terminal app (Ctrl+Alt+T)
Type gksudo gedit
Type your password when asked for it (it will not show nothing, even asterisks) and press Enter
Text editor will open up
Then select Open and open the file to edit
Edit the file
Save the file

edited Aug 05 '16 at 23:06

David Foerster

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answered Mar 13 '15 at 14:39

0x2b3bfa0

8,780
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Grub can't be saved after modification

2 Answers2