Linux Group Commands

Command	Function	Flags
groupadd	Creates a new group.	-g (Defines the group ID) -p (Defines the group password) -r (Makes the new group a system group)
groupmod	Modifies the existing group.
groupdel	Modifies the system account files by deleting all entries that refer to the specified group.
gpasswd	Changes a group password.	-r (Removes a group password)
newgrp	Used to change the current group IP during a login session.
usermod	Modifies group membership for the user account.	-g (Assigns a user to a primary group) -G (Assigns a user to a secondary group) -aG (Assigns a user to a secondary group by adding it to the list of secondary users) -G "" (Removes the user from all secondary group memberships)
groups	Displays the primary and secondary group membership for the specified user account.