My system specifications are: Ubuntu 12.04, 64-bit, Acer Aspire One D270, Intel Atom CPU

The usual brightness increase/decrease key combination using Fn key doesn't work in Ubuntu as many pointed out.

I had found two solutions on this forum to set the screen brightness.

One was to make the usual key combination work answer is given here:

Is there a way to set a hotkey to change screen brightness?

and the other is using the command

sudo setpci -s "00:02.0" F4.B=20

where the 20 is a hexadecimal number representing brightness.

It's only the latter that worked in my case.

I observe that the original brightness setting is restored after resumption from sleep mode.

All I want is to keep my brightness setting permanent. How do I do that?

Try 1: Tried Alok's suggestion. It just sits there as a startup application. Doesn't figure as an icon on the topbar of the screen, like the dropbox icon (my dropbox account it is linked to ubuntu) so that I can conveniently change the brightness.

Try 2: Also I must add, that the method System Settings -> Additional Drivers gives an empty list. In my earlier install (which I had to overwrite-reinstall :-(), the list had (I think) Intel Cedarview Graphics Driver. So must I install before trying the methods in any of the answers below?

Update: I read somewhere Intel CedarView is only for 32-bit OS!

Try 3: Just tried the quiet_splash etc that I had to add to /etc/default/grub, even read the thread given in one of the answers below!

Temporarily settled myself with this method:

#!/bin/bash

echo "Set Brightness (Values 00-FF): "

read s

sudo setpci -s "00:02.0" F4.B=$s

export BRI=s