Add Group

$groupadd [group]

Add User To Group

$sudo usermod -a -G [groupname] [username]

ex. sudo usermod -a -G plex andy

always use "-a" for append or it will add user and remove all rest

Remove User from Group

$ sudo gpasswd -d [groupname] [username]

# Change Group Ownership

$chown :[group] [file]
to change all contents use [-R]

ex. chown -R :[group] [file]

Change both User and Group

can also change group at same time
$chown [user]:[group] [file]

Delete Group

$ sudo groupdel [groupname]

Change Users Primary Group

$ sudo usermod -g [group] [user]

Display User Groups

$ id [username] or id for current user
displays all groups of which that user is a member of