在影子文件 ( /etc/shadow) 中并阅读其文档后，密码字段显示：
Password, 13 character encrypted. A blank entry (eg. ::) indicates a password is not required to log in (usually a bad idea), and a ``*'' entry (eg. :*:) indicates the account has been disabled.
但是，这到底意味着什么：
``*'' entry (eg. : * :) indicates the account has been disabled
因为在这种情况下
root:*:17848:0:99999:7:::
我可以继续使用根数。