Re: expand-file-name leaves "/../" in expansions at times

[Jan Djärv]

Miles Bader skrev:
> Chong Yidong <address@hidden> writes:
> > On the other hand, I just checked, and this behavior seems to have
> > been around since at least Emacs 20.  Glancing through the source
> > code, this behavior seems to be deliberate---something to do with the
> > "superroot directory".  Maybe someone on this list can elucidate?
>
> I don't know anything about the Emacs code, but CMU CS had a networked
> filesystem (the mach/spice project vaxes) which had the concept of a
> super-root above /, accessed via "/..".  E.g. to access file "/x/y" on
> machine "blargh", you'd use "/../blargh/x/y" (IIRC, "/.." was a real
> directory so you could do "cd /..", "ls /.." to see all machines, etc)..
>
> I always thought it was a rather clever idea.  It certainly messes up
> assumptions some programs make, but I think the "/.." == "/" assumption
> is generally rather rare in practice.  [Compare to the microsoftian "//"
> superroot syntax, which messes up the far more common "//" == "/"
> assumption, and just generally feels a lot more arbitrary.]

Apollo also had // as superroot if my memory is correct.  You could do
% ls //
to see all machines there as well.  I don't know if this predates Microsofts 
usage, but I suspect it does, this was late 80:s, early 90:s.

        Jan D.