root用户登录，进入xx用户（非管理员）目录下，删除xx用户，
导致xx用户目录删除了，无法去到其他目录。
[root@HUIHUT /home/xx]$ userdel xx
User has deleted.
[root@HUIHUT /home/xx]$ ls
Permission denied.
[root@HUIHUT /home/xx]$ cd ..
cd ..: No such file or directory.
[root@HUIHUT /home/xx]$ cd
[root@HUIHUT ~ome/root]$ ls
drwxr-xr-x 2 root root 512 B 2017.12.22 23:55:50 .
drwxr-xr-x 3 root root 512 B 2017.12.22 23:55:50 ..
[root@HUIHUT ~ome/root]$ cd ..
[root@HUIHUT /home/xx/home]$ ls
drwxr-xr-x 3 root root 512 B 2017.12.22 23:55:50 .
drwxr-xr-x 3 root root 512 B 2017.12.22 23:55:48 ..
drwxr-xr-x 2 root root 512 B 2017.12.22 23:55:50 root
[root@HUIHUT /home/xx/home]$ cd ..
[root@HUIHUT /home/xx]$ ls
drwxr-xr-x 3 root root 512 B 2017.12.22 23:55:48 .
drwxr-xr-x 3 root root 512 B 2017.12.22 23:55:50 home
drwxr-xr-x 5 root root 512 B 2017.12.22 23:55:50 etc
通过先返回根目录再删除xx用户解决部分问题，仍有当前目录名错乱的问题。
[root@HUIHUT /home/xx]$ userdel xx
Permission denied.
User has deleted.
[root@HUIHUT /]$ ls
drwxr-xr-x 3 root root 512 B 2018.1.2 12:09:43 .
drwxr-xr-x 3 root root 512 B 2018.1.2 12:09:49 home
drwxr-xr-x 5 root root 512 B 2018.1.2 12:09:49 etc
[root@HUIHUT /]$ cd home
[root@HUIHUT /home]$ ls
drwxr-xr-x 3 root root 512 B 2018.1.2 12:09:49 .
drwxr-xr-x 3 root root 512 B 2018.1.2 12:09:43 ..
drwxr-xr-x 2 root root 512 B 2018.1.2 12:09:49 root
[root@HUIHUT /home]$ cd root
[root@HUIHUT ~e/root]$ pwd
/home/root
root用户，在xx（非管理员）用户目录下，touch文件，会有Permission denied.，mkdir创建目录则可以创建。
不可第二次登录，提示找不到目录，当前只能删除sys文件重装。
-----------------------------------------
Wellcome to MFS(Meng-File-System)
If you need help, please type 'help'.
-----------------------------------------
$ ls
ls: command not found...
If you need help, please type 'help'.
$ login
username: root
password:
cd etc : No such file or directory.
User does not exist.
cd .. : No such file or directory.
$