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Re: cd // produces unexpected results

From: Bob Proulx
Subject: Re: cd // produces unexpected results
Date: Sat, 23 Jun 2012 15:11:41 -0600
User-agent: Mutt/1.5.21 (2010-09-15)

Stefano Lattarini wrote:
> A little more info, quoting from the Autoconf manual:

And I will respond to the quoted part from the autoconf manual
realizing that Stefano isn't saying it but just passing the message
along. :-)

>   POSIX lets implementations treat leading // specially, but requires leading
>   /// and beyond to be equivalent to /.  Most Unix variants treat // like /.
>   However, some treat // as a "super-root" that can provide access to files
>   that are not otherwise reachable from /.  The super-root tradition began
>   with Apollo Domain/OS, which died out long ago, but unfortunately Cygwin
>   has revived it.

I don't think that should say "unfortunately" there.  Apollo Aegis
started it with an "unfortunate" network model.  But that was Apollo
not Cygwin.  And because of that it was swept into the POSIX standard.
It existed in the wild with Aegis Domain/OS and therefore the Portable
Operating System Interface standard needed to incorporate the behavior
as existing behavior in what was at one time a popular system.  And
then with the passage of time Domain/OS is now no longer seen.
However the standard still exists.

Cygwin had a very similar behavior model that needed to be handled.
Cygwin I think did okay by making use of the existing standard rather
than creating something new.  The alternative would have been a
different, unique, non-standard syntax and that would have been bad.
But they fit within the standard.  Any previously standard conforming
and well behaved script would still be standard conforming and well
behaved.  That being the whole point of the POSIX standard I see this
as a good thing.


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