故事背景
root@bionic:~# ls -l a1
---------- 1 root root 3 Jul 22 06:58 a1
root@bionic:~# cat a1
A1
原因解释
1.As root, change the permissions of a file to 000. This file and its contents can only be accessed by root.
2.As a user, change the permissions of your own file. The file and its contents cannot be accessed by the user. But the root has full privileges on the file.