usermod
usermod功能说明：修改用户帐号。
语 法：usermod [-LU][-c <备注>][-d <登入目录>][-e <有效期限>][-f <缓冲天数>][-g <群组>][-G <群组>][-l <帐号名称>][-s <shell>][-u <uid>][用户帐号]
补充说明：usermod可用来修改用户帐号的各项设定。
参 数：
-c<备注> 修改用户帐号的备注文字。
-d登入目录> 修改用户登入时的目录。
-e<有效期限> 修改帐号的有效期限。
-f<缓冲天数> 修改在密码过期后多少天即关闭该帐号。
-g<群组> 修改用户所属的群组。
-G<群组> 修改用户所属的附加群组。
-l<帐号名称> 修改用户帐号名称。
-L 锁定用户密码，使密码无效。
-s<shell> 修改用户登入后所使用的shell。
-u<uid> 修改用户ID。
-U 解除密码锁定。
usermod
usermod [options] user
System administration command. Modify user account information.
Options
Comment field.
Home directory.
Account expiration date. date is in the format MM/DD/YYYY; two-digit year fields are also accepted. The value is stored as the number of days since January 1, 1970. This option requires the use of shadow passwords.
Permanently disable account this many days after the password has expired. A value of -1 disables this feature. This option requires the use of shadow passwords.
Initial group name or number.
Supplementary groups given by name or number in a comma-separated list with no whitespace. user will be removed from any groups to which it currently belongs that are not included in groups.
Login name. This cannot be changed while the user is logged in.
Lock user's password by putting a ! in front of it. This option cannot be used with -p or -U.
Override. Accept a nonunique uid with the -u option.
Encrypted password, as returned from crypt(3).
Login shell.
Numerical user ID. The value must be unique unless the -o option is used. Any files owned by user in the user's home directory will have their user ID changed automatically. Files outside of the home directory will not be changed. user should not be executing any processes while this is changed.
Unlock the user's password by removing the ! that -L put in front of it. This option cannot be used with -p or -L.