Linux系统的一大块就是用户管理，管理用户的信息，这里介绍用户。
常用的命令有useradd , userdel , usermod , users
【基本操作】
添加用户
[root@bogon ~]# useradd --help
Usage: useradd [options] LOGIN
Options:
-b, --base-dir BASE_DIR base directory for the home directory of the
new account
-c, --comment COMMENT GECOS field of the new account
-d, --home-dir HOME_DIR home directory of the new account
-D, --defaults print or change default useradd configuration
-e, --expiredate EXPIRE_DATE expiration date of the new account
-f, --inactive INACTIVE password inactivity period of the new account
-g, --gid GROUP name or ID of the primary group of the new
account
-G, --groups GROUPS list of supplementary groups of the new
account
-h, --help display this help message and exit
-k, --skel SKEL_DIR use this alternative skeleton directory
-K, --key KEY=VALUE override /etc/login.defs defaults
-l, --no-log-init do not add the user to the lastlog and
faillog databases
-m, --create-home create the user's home directory
-M, --no-create-home do not create the user's home directory
-N, --no-user-group do not create a group with the same name as
the user
-o, --non-unique allow to create users with duplicate
(non-unique) UID
-p, --password PASSWORD encrypted password of the new account
-r, --system create a system account
-s, --shell SHELL login shell of the new account
-u, --uid UID user ID of the new account
-U, --user-group create a group with the same name as the user
-Z, --selinux-user SEUSER use a specific SEUSER for the SELinux user mapping
简单实例
useradd -c "This user cannot login to a shell" -s /sbin/nologin username #添加用户，但是不能登入shell useradd -c "This user login by bash" -s /bin/bash username #添加用户登入用后环境是bash useradd -d /usr/username username #添加用户并指定加目录，默认是/home下面 useradd -s /bin/sh -g group -G adm,root gem #添加用户指定shell,主组是group,从组是adm，root,gem
删除用户
[root@bogon ~]# userdel --help
Usage: userdel [options] LOGIN
Options:
-f, --force force removal of files,
even if not owned by user
-h, --help display this help message and exit
-r, --remove remove home directory and mail spool
-Z, --selinux-user remove SELinux user from SELinux user mapping
简单实例
userdel username #删除用户(passwd ,shadow)，但是不会删除该用户的家目录 userdel -r username #删除用户，包括家目录
修改用户
[root@bogon ~]# usermod --help
Usage: usermod [options] LOGIN
Options:
-c, --comment COMMENT new value of the GECOS field
-d, --home HOME_DIR new home directory for the user account
-e, --expiredate EXPIRE_DATE set account expiration date to EXPIRE_DATE
-f, --inactive INACTIVE set password inactive after expiration
to INACTIVE
-g, --gid GROUP force use GROUP as new primary group
-G, --groups GROUPS new list of supplementary GROUPS
-a, --append append the user to the supplemental GROUPS
mentioned by the -G option without removing
him/her from other groups
-h, --help display this help message and exit
-l, --login NEW_LOGIN new value of the login name
-L, --lock lock the user account
-m, --move-home move contents of the home directory to the
new location (use only with -d)
-o, --non-unique allow using duplicate (non-unique) UID
-p, --password PASSWORD use encrypted password for the new password
-s, --shell SHELL new login shell for the user account
-u, --uid UID new UID for the user account
-U, --unlock unlock the user account
-Z, --selinux-user new SELinux user mapping for the user account
简单实例
usermod -d /usr/tttt -m tttt #移动家目录到/usr/tttt usermod -d /usr/tttt tttt #修改家目录到/user/tttt，原来的/home/tttt还保留 usermod -s /bin/ksh -d /home/z -g developer sam #用户sam的登录Shell修改为ksh，主目录改为/home/z，用户组改为developer
查看用户信息：finger , id
NAME
finger - user information lookup program
SYNOPSIS
finger [-lmsp] [user ...] [user@host ...]
DESCRIPTION
The finger displays information about the system users.
finger 用户名 ----可以查看用户的相关信息，包括用户的主目录，启动shell，用户名等
finger -l 用户名----以长格式显示用户信息
finger -s 用户名 ----以短格式显示用户信息
[root@bogon srv]# finger spark Login: spark Name: Spark Directory: /home/spark Shell: /bin/bash On since Tue Jul 15 16:56 (CST) on tty1 from :0 23 days 18 hours idle No mail. No Plan.
[root@bogon srv]# id --help
Usage: id [OPTION]... [USERNAME]
Print user and group information for the specified USERNAME,
or (when USERNAME omitted) for the current user.
-a ignore, for compatibility with other versions
-Z, --context print only the security context of the current user
-g, --group print only the effective group ID
-G, --groups print all group IDs
-n, --name print a name instead of a number, for -ugG
-r, --real print the real ID instead of the effective ID, with -ugG
-u, --user print only the effective user ID
--help display this help and exit
--version output version information and exit
【参考】
http://www.g-loaded.eu/2005/11/06/manage-users-from-the-command-line/
http://www.cnblogs.com/end/archive/2011/05/25/2057129.html