Users

id                                   -> shows details of the active user
last                                 -> shows the last logins onto the system
who                                  -> shows who is logged into the system
w                                    -> shows who is logged in and their activity
groupadd [group_name]                -> adds a new group
adduser [user_name]                  -> adds new user
usermod -aG [group_name] [user_name] -> adds a user to a group
userdel [user_name]                  -> deletes a user
usermod                              -> uses for changing / modifying user information