file permissions don't work when running as 'root'

[valan]

If you're using single user mode or root for everything, then your system is no more secure than Windows. In my opinion, that's just plain stupid, and it's your own fault if you get hacked or something of the sort.

[Stormblazer]

Because root is the superuser, so it has complete access. However, I think I know a way to do what you ask. The first to simple mount the filesystem as read-only, but don't do that with the root filesystem.
The second way is this:
Create another user and add them to the "root" group. That way you'll have close to root permissions, but still be able to have the advantages of not being root. And the other people are right, running linux as root on a general basis is VERY bad for security.

A third way would be to try something with PAM or SELinux, but I have no idea how.

[n0tt00elite]

That is correct that is one of the reasons you should not be logged in as root and do maintenance task throught the use of

su -

and

sudo

But why shouldn't it work? The Windows NT/XP ACL's work even when running as Administrator, so it is possible to prevent accdental overwriting of a file. Logging in as a super user should not bypass file permissions, but has the right to change it. I hope this bug would be fixed in future Linux kernel releases.

Since when should Windows be used as a standard for anything to be tested against? Windows automatically preloads Internet Explorer, should Linux automatically preload Firefox? I don't think so! If you want Windows, use Windows, and don't complain about 'bugs' that keep you from doing the idiotic stuff Windows does. So this (very useful) feature will not be removed.

[scientica]

That is correct that is one of the reasons you should not be logged in as root and do maintenance task throught the use of

su -

and

sudo

But why shouldn't it work? The Windows NT/XP ACL's work even when running as Administrator, so it is possible to prevent accdental overwriting of a file. Logging in as a super user should not bypass file permissions, but has the right to change it. I hope this bug would be fixed in future Linux kernel releases.

that's because "admininistrator", by design not bug, can't do everyhing - in *nix/linux root can do anything, even remove all files in the whole system - but really, it's not that much of a kick, mostly bothersome, you'll have to re-install...
Also, to say it again: it's not a bug, think of root in *nix as a sort of "god", what root can't do, no one can. This is also true for the phrase "don't take the name of root in vain" - ie, don't log in as root if you don't have to.

I like to run Linux in single-user mode, so it's a big problem. (I didn't even create a normal, non-root user account.)

Well, running every thing as root is bad. I've seen figures that of the, relativly rare, exploits 80-99% of them are only "harmfull"* when logged in as root.
But exploits aren't your worst headace as root, main it's one self, eg, accidentally typing "*" instead of "*~" in certain folders is virtually killing the system. (close windows equivalent is "format /q /Vwnd C:")

* harmfull = system damages, you could still loose files writable by "you" (and if you happen to be root that'd be _everything_)

[Stormblazer]

I think what he's trying to do is simply prevent the file from being overwritten. On that basis, why don't you just back up the file instead? And why is it in danger of being overwritten in the first place?
Those answers would be more helpful to us to solve the real problem (preventing a file from being overwritten by accident).