[root@localhost david]# tail -n 2 /etc/group                            //查看组信息

user01:x:502:

group01:x:503:

[root@localhost david]# groupmod -g 999 -n group02 group01           //修改组id：999，组名字：group02

[root@localhost david]# tail -n 2 /etc/group                            //查看组信息，已经修改

user01:x:502:

group02:x:999: