File permission

help
1

It is not a rust problem. I meet it when I use rust to read file. I change a file's permission to None on Linux. But I can read it after that.

2

If you take away the permission to read the file, then it is not a surprise that you can't read it.

3

The problem is that I take away the permission but I can still read it.

4

Aha. In that case it is probably because you are the owner of the file.

5

I see. I will try it as other user.

6

What exactly a None permission on Linux? In Linux file permissions are represented by three octal digits - one for the user, one for the group and one for everyone else. If I am not mistaken, by None permission, you mean you have done something like chmod 000 file. But in that case, you cannot read that file at all, even if you own it.

7

I can read it after I chmod 000 file. That's why I am so confused.

8

Can you do a ls -l <filename and paste the output?

9

4537F5EC-AFF6-4770-80B2-6C095D08AB07
It's the a.txt

10

Are you running as root perhaps? The # prompt makes me think so. root has a number of "super-user" capabilities, which include ignoring file permissions.

Take a look at man capabilities, e.g.:

   CAP_DAC_OVERRIDE
         Bypass file read, write, and execute permission checks.\
         (DAC is an abbreviation of "discretionary access control".)
1 Like
11

That's because you are root.

1 Like
12

I see

13

My advice is "Do not play or experiment when logged in as root"

3 Likes
14

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