Linux User User Group related commands

Linux add Users (user) to user groups (group)

Add a user to a user group and never use it directly:
Usermod-g Groupa

Doing so will allow you to leave the other user groups, just as members of this user group Groupa.
Should be added with the-a option:
Usermod-a-G Groupa User

(fc4:usermod-g GROUPA,GROUPB,GROUPC user)
-A represents append, which is to add itself to the user group Groupa without having to leave another user group.

Remove a user from a user group

Remove the test user from the wheel group
GPASSWD wheel-d Test

Linux User User Group related commands