1: Add user group: groupadd [option] group name
Options: -g GID: Specify the group ID
2: Modify user group: groupmod [option] group name (usually not needed)
Options: -g GID: modify group ID
-n new group name: modify the group name
3: Delete the user group groupdel group name
Has been deleted
If there is an initial user in this group, it cannot be deleted, additional users will not affect the deletion
At this time, deleting will report an error
Indicates that the initial user cannot be deleted, additional users can be deleted
4: Add the user to the group or delete the gpasswd option group name from the group (the user who operates the gpasswd is the additional user)
Options: -a username: add the user to the group
-d username: remove the user from the group
Add the lamp user to the root group
Remove user lamp from root group
