index of file

how i can get index of file? and what is it

Can you provide some more context, please?

What is the index number of the “passwd” or “shadow” or “sudoers” file and how to get it

it’s question from academy lesson

I am not 100% sure I have understood this, and I’ve never looked at the Academy stuff (but I thought it was a bit more tutorial based, so I am surprised they haven’t explained it).

At a guess, it might relate to the inode number which you can get with ls -il - it is the first number on the line.

use stat comand…
stat /path/to/file
the Inode number is the index of the file

Both worked: the ls -il command, and the stat/path/file_name command. This second option will give you a more direct answer since you won’t need to look for the file in a list.
You just need to make sure you are doing it as the htb_student and not as user82209.