To list all the groups, including ones used only by the system. Just type:
To list all the groups of which the current user is a member.
To add a user use
To add a user to a specific group use
usermod -G name-of-group -a ‘name-of-user‘
For more information on all these – and it’s really a good idea to make sure you know what you’re doing before doing system-level commands — you can type:
For instance “man useradd”.