I faced the same problem on my Dell XPS. Currently there is no other way to save it according to brightness key.


First try executing 

sudo su -c 'echo 5 &gt; /sys/class/backlight/acpi_video0/brightness'



If it succed,try with different value for 5 and choose your preference level.


Now edit /etc/rc.local file to execute this command at boot up.

gksu gedit /etc/rc.local

Just before exit in the file, add the following line,

echo 5 &gt; /sys/class/backlight/acpi_video0/brightness



You can change value 5 to anything.

How do I prevent Ubuntu from changing my laptop screen brightness level?
Does ISO-Prolog have any prescriptions / recommendations
 regarding the representation of negative integers and operations on them? 2's complement, maybe? 

Asking as a programmer/user: Are there any assumptions I can safely make when performing bit-level operations on negative integers?
