Set Screen Brightness from Terminal
We can set screen brightness from terminal by using xbacklight. Intially we have to install it before using. Open your terminal and type as
sudo apt-get install xbacklight
and then to set brightness to 10% more execute the command as
xbacklight -inc 10
To decrease brightness by 10%
xbacklight -dec 10
If you want to set the brightness to some level then, you can use the command as
xbacklight -set 50
The above command will set the brightness to 50. It will range from 0 to 100.
If you have any issues you can use comments to let me know.
Hope that helps.