With Ubuntu 14.04, by default there are no options to modify the brightness of the system. However there is an app for same called brightness controller. But I had problems setting up the brightness for the boot time itself. So I decided to find out how did the Brightness Controller work. I downloaded the source code from the git page and found out that internally it uses the Xrandr . So I added the Xrandr command to my bashrc file and now I don’t have to set the brightness every time.
jkapil@jkapil-desktop:~$ xrandr
Screen 0: minimum 320 x 200, current 1366 x 768, maximum 32767 x 32767
VGA1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1366x768 60.0*+
1024x768 75.1 70.1 60.0
800x600 72.2 75.0 60.3
640x480 75.0 72.8 60.0
720x400 70.1
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
This gives you the output names associated with your display. In my case its VGA1. To set the brightness,
$xrandr --output VGA1 --brightness 0.7
–brightness value is in between 0 and 1 and is a fraction. First execute in terminal to find out the brightness value soothing to your eye and then put that value with the above command in your .bashrc file in home directory.