One silly chmod question

[m.roth at 5-cent.us]

> Hi all,
>
> I have a problem changing permissions to some files using chmod and now I
> have a doubt about the owner and group of a file,
>
> I´ll try to explain.
>
> I have 2 users, user1 and user2, both belongs to group1.
>
> I have a file with this permissions:
> -rwxrwxrwx 1 user1 group1 file.txt
>
> with user2 I can read, write this file. but If I try to change the
> permissions with this:
> chmod 770 file.txt I get the error:
> operation not permitted,
>
> so my doubt is, only the owner can change the permissions to a file?

Think about the *meaning* of what you tried to do: you, as a member of the
group, but not as the owner, are trying to make it so that the owner
cannot even look at the file, not execute, not write, not even read. Does
that make sense?

        mark