Re: Does /var/shm still need to be mounted?

From: H. Peter Anvin (
Date: Fri Jun 02 2000 - 20:30:36 EST

Ulrich Drepper wrote:
> "H. Peter Anvin" <> writes:
> > The distinction you're referring to is the distinction of a real path
> > versus a bogus path -- you cannot under any circumstances construct a
> > path which uses one of those artificial roots.
> >
> > POSIX IPC requires a real path. It needs to be in the real namespace,
> > which starts with /.
> There are several things wrong with this.
> POSIX shm function require a name. This is left very vague for good
> reason. The only other requirement made for portable program is that
> the names must start with a slash. The handling os slashes in the
> name (i.e., if the name actually is a pathname) is left implementation
> defined.
> What is not the case (and I think you meant this) is that if the name
> given to shm_open() is a pathname, the name must also be available in
> this form in the normal filesystem hierachy. This is not the case
> even if the name is used somewhere in the filesystem tree.
> Take a look at the shm_open() implementation in glibc 2.2. It gets
> very clear what I mean if you see the code.

This is true based on what the POSIX requirements are, but what I wrote
is true *for the Linux implementation of POSIX shm.* We did it that way
because it makes sense.


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