Ubuntu – Make xconf configuration permanent

This is supposed to be configurable in the energy options, set the brightness to the desired level and it will always be used. If you use a laptop you will also need to configure the level for battery mode as well...

I found that Gnome has some issues about lcd panel brightness, e.g. if I run on battery mode and set the brightness manually to a given level and leave the laptop unattended for 10 seconds it will go back to the preset brightness when I take control back. Same goes when on A/C mode except it takes longer so goes unnoticed more easily. I believe all those settings should be saved somewhere and restored - at least for A/C mode.

EDIT: For gnome3 this does not work (at least for me).

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

sudo -H gedit /etc/rc.local

and add the following

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

so that the end result looks like this

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

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

exit 0

Substitute X by the desired brightness level.

In case /etc/rc.local doesn't exist, as is the case with new Ubuntu releases, you'll need to create it, and make eecutable with the following commands:

printf '%s\n' '#!/bin/bash' 'exit 0' | sudo tee -a /etc/rc.local
sudo chmod +x /etc/rc.local

PS: Alternatively, there may be /sys/class/backlight/acpi_video0/brightness instead of the above. Brightness levels vary wildly, and may range from 0 to 10 or to 1000. To find the maximum value, try

cat /sys/class/backlight/acpi_video0/max_brightness
or
cat /sys/class/backlight/intel_backlight/max_brightness