Add user to existing group
For some mysterious reason I just cannot remember how to do this for the last 15 times. So time to write this thing down. Adding a user david to an existing group audio in Linux:
# usermod -a -G audio david
Don't forget to use sudo in Ubuntu. I've also noticed that shells don't react to this until you relogin.
Changin users primary group is done the following way:
# usermod -g audio thefreakdj
To list all groups that current user belongs to, try this one: