摘要：本文简要介绍了Linux帐号管理的用户组管理。
Linux: Ubuntu10.0.4
1.新增用户组：groupadd
Usage: groupadd [options]
Options:
-f, --force exit successfully if the group already exists,
and cancel -g if the GID is already used
-g, --gid GID use GID for the new group
-h, --help display this help message and exit
-K, --key KEY=VALUE override /etc/login.defs defaults
-o, --non-unique allow to create groups with duplicate
(non-unique) GID
-p, --password PASSWORD use this encrypted password for the new group
-r, --system create a system account
2.修改用户组：groupmod
Usage: groupmod [options]
Options:
-g, --gid GID change the group ID to GID
-h, --help display this help message and exit
-n, --new-name NEW_GROUP change the name to NEW_GROUP
-o, --non-unique allow to use a duplicate (non-unique) GID
-p, --password PASSWORD change the password to this (encrypted)
PASSWORD
3.删除用户组：groupdel
用法：groupdel 组
4.用户组管理员：gpasswd
Usage: gpasswd [option]
Options:
-a, --add USER add USER to GROUP
-d, --delete USER remove USER from GROUP
-r, --remove-password remove the GROUP's password
-R, --restrict restrict access to GROUP to its members
-M, --members USER,... set the list of members of GROUP
-A, --administrators ADMIN,...
set the list of administrators for GROUP
Except for the -A and -M options, the options cannot be combined.
5.查看有效用户组：groups
fans adm dialout fax cdrom
6.切换有效用户组：newgrp
