expiry - check and enforce password expiration policy
The expiry command checks (-c) the current password expiration and forces (-f) changes when required. It is callable as a normal user command.
The options which apply to the expiry command are:
-c, --check
Check the password expiration of the current user.
-f, --force
如果用户密码过期，则强制用户修改密码。
-h, --help
显示帮助信息并退出。
/etc/passwd
用户账户信息。
/etc/shadow
安全用户账户信息。