I have a Sony Vaio VPCEG15FX, I have been trying to install Ubuntu, but the same problem occurs with the screen, I am unable to control the Brightness using the laptop Hot keys.
Until two days ago I was able to control the screen brightness with a specific Instruction (Among so many different options that I found but never worked), which I used according to what I read in one post (Can't adjust brightness in a sony vaio T13 ultrabook), as follows :
echo 1000 > /sys/class/backlight/intel_backlight/brightness
Which I entered in the folowing file : /etc/rc.local.
I have read different posts, different solutions, scripts, etc.; I don't know if I am the only Sony vaio user of this specific Model with this problem, but I would like to be able to use the Hot Keys (FN + F5 : FN + F6).