How to prevent superuser from modifying a file?

Question

linux

Hello.
I am just starting to learn linux. Interested in how you can prohibit changing the file for root'a. For example, how is this possible:

[email protected]:~# ls -lh /etc/sysctl.conf
-rw-r--r-- 1 root root 19 Dec 27 17:16 /etc/sysctl.conf
[email protected]:~# > /etc/sysctl .conf
-bash: /etc/sysctl.conf: Permission denied

Answer 1

Offhand
1. Selinux
2. FS in RO.
But if a competent root, everything can get around :)

Answer 2

The file does not have execution rights (+x), bash tells you about this when you try to run it.

Answer 3

What is impossible here?
-a regular file (not a directory - d, and not some kind of link - l)
rw- the current user has the right to read (r) and write (w), but cannot execute the file (-)
r--users from the current group (root) have the right to read (r), but do not have write (-) and execute file (-)
r--all other users (read - World) have read (r), but do not have write (-) and file execute (- )
root rootthe current user from the root group
The command does not change the file, it executes it (after reading it) :) PS Here you can read about the prohibition of editing files even by the root user. But the limitation is rather arbitrary.