> On Thu, 27 Sep 2007, Mark Andrews wrote:
> (I wrote:)
> > > On Tue, 25 Sep 2007, LI Xin wrote:
> > > > Oliver Fromme wrote:
> > > > > Nicolas Rachinsky wrote:
> > > > > > Oliver Fromme wrote:
> > > > > > > By the way, an additional confusion is that ".." and "../"
> > > > > > > are handled differently. Specifying ".." always leads to
> > > > > > > this message:
> > > > > > >
> > > > > > > rm: "." and ".." may not be removed
> > > > > > >
> > > > > > > and nothing is actually removed. It is confusing that
> > > > > > > adding a slash leads to a different error message _and_
> > > > > > > removal of the contents of the parent directory. Clearly
> > > > > > > a POLA violation.
> > >
> > > Clearly a bug, and well spotted, especially if as old as reported.
> > >
> > > > > >
> > > > > > Adding a slash often leads to different behaviour.
> > > > >
> > > > > Yes, I'm aware of that. I often make use of the feature
> > > > > that "find /sys/" expands the symlink, while "find /sys"
> > > > > does not. The same holds true for ls(1).
> > >
> > > But fortunately not for rm(1):
> > >
> > > The rm utility removes symbolic links, not the files referenced by
> the
> > > links.
> > >
> > > It is an error to attempt to remove the files /, . or ..
> > >
> > > > > However, I would still argue that there is no sane reason
> > > > > for "rm -rf ../" behaving differently from "rm -rf ..",
> > > > > especially because it behaves differently in a destructive
> > > > > way. That's why I call it a POLA violation.
> > > >
> > > > Also a POSIX violation IMHO :-)
> > >
> > > Indeed; I can't imagine a situation where removing "." (let alone "..")
> > > and so orphaning the pwd might be considered sane, never mind legal ..
> > > but maybe I lack imagination :)
> >
> > You lack imagination.
>
> No doubt :)
>
> > When you found the directory you want to remove and you are
> > in it it is much less error prone to remove "." recursively
> > that to go up one directory and try to find the directory
> > you were just in.
>
> Sorry, I can't agree. I take comfort in knowing that 'rm .' will fail,
> that 'rm *' will not remove '.' (let alone '..'!), and that rm will not
> orphan the pwd. Neither will umount, for that matter ..
You asked to be shown a example. It's a perfectly reasonable
example.
> > The the prohibitions comes from when you literally removed
> > directories by unlinking the directory and "." and ".."
> > within the directory in user space. It was easy to stuff
> > up a directory structure.
>
> Regardless of how implemented in the filesystem, having the pwd become
> invalid isn't something I ever expect to happen, and I'll continue to
> rely on: 'It is an error to attempt to remove the files /, . or ..'
It's something that you need to expect on a multi-process system.
It happens to me one or twice a month.
Mark
> Cheers, Ian
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: [EMAIL PROTECTED]
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