I have an application (created by IBM Linux team) that controls all the buttons on my thinkpad and shows the changes visually (raise/lower the speaker volume, increase/decrease brightness …etc). This application is called “tpb” and I found out that it cannot be run except by user root :(. Of course when I tried to put it in the session startup in my Ubuntu box – without adding sudo or gksudo before it – it never ran as expected and I really didn’t want to enter the root password each time I run this nice app.

Anyway, I searched and found a method to allow me to run this tool using another user, but with the privileges of the owner (which is root in this case), you can simply do the following:

“chmod 6555 tpb”

This made me able to run it as any other application using my system user instead of root, and it ran like a charm :))

Source: http://www.unix.com/tips-tutorials/19060-unix-file-permissions.html