Because users group membership is defined in two different locations, it can be difficult to find out which groups exactly a user is a member of. A convenient command to check this is groupmems . Use, for example, the command groupmems -g sales -l to see which users are a member of the group sales. This shows users who are a member of this group as a secondary group assignment, but also users who are a member of this group as the primary group assignment.
[root@rhel7 ~]# groupmems --help
Usage: groupmems [options] [action] Options:
-g, --group groupname change groupname instead of the user's group
(root only)
-R, --root CHROOT_DIR directory to chroot into Actions:
-a, --add username add username to the members of the group
-d, --delete username remove username from the members of the group
-h, --help display this help message and exit
-p, --purge purge all members from the group
-l, --list list the members of the group
例：
查看有哪些用户属于sales组
[root@rhel7 ~]# groupmems -g sales -l
linda lisa
从sales组中删除lisa
[root@rhel7 ~]# groupmems -d lisa -g sales
[root@rhel7 ~]# groupmems -g sales -l
linda
添加用户到组里
[root@rhel7 ~]# id lxj2
uid=(lxj2) gid=(root) groups=(root)
[root@rhel7 ~]# groupmems -a lxj2 -g sales
[root@rhel7 ~]# id lxj2
uid=(lxj2) gid=(root) groups=(root),(sales)
也可以使用usermod命令将用户添加到组里
usermod -aG will add users to new groups that will be used as their secondary group.
Use usermod to add users linda and lisa to the group sales, and lori and bob to the group account:
usermod -aG sales linda
usermod -aG sales lisa
usermod -aG account lori
usermod -aG account bob