课堂笔记，共学共享~~加油！
[root@long ~]# passwd test 为test用户设置密码
[root@long ~]# passwd -S test 查看test账户的密码信息
test PS 2009-01-08 0 99999 7 -1 (Password set, MD5 crypt.)
[root@long ~]# passwd -S test1 从未设置过口令的账户其口令为锁定状态
test1 LK 2009-01-07 0 99999 7 -1 (Password locked.)
[root@long ~]# passwd -d test 删除test账户的口令
[root@long ~]# passwd -S test 查看test账户口令的信息，结果为空口令
test NP 2009-01-08 0 99999 7 -1 (Empty password.)
[root@long ~]# passwd -l test 锁定test的口令，test用户就不能自己修改自己的口令了
[root@long ~]# passwd -S test 查看test账户口令的信息，结果为锁定状态
test LK 2009-01-08 0 99999 7 -1 (Password locked.)
[root@long ~]# passwd -u test 尝试解锁一个空口令的账户，
Unlocking password for user test. 不知道test用户的口令
passwd: Unsafe operation (use -f to force). 系统提示这样做不安全，如果确认要这么做的话，就用-f强制解锁
[root@long ~]# passwd -uf test 强制解锁一个空口令的账户
[root@long ~]# passwd -S test
test NP 2009-01-08 0 99999 7 -1 (Empty password.)密码为空
[root@long ~]# passwd -k test 设置test账户只有密码过期失效后，才能更新
Changing password for user test.
New UNIX password:www.163.com
Retype new UNIX password:www.163.com
passwd: expired authentication tokens updated successfully.
