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Date: Wed, 12 May 2004 12:17:12 -0400
From: "Pierre A. Humblet" <pierre DOT humblet AT ieee DOT org>
To: cygwin AT cygwin DOT com
Subject: Re: bash: tab completion failure from (but not at) /
Message-ID: <20040512161712.GA349175@Worldnet>
References: <20040512140835 DOT GJ12030 AT cygbert DOT vinschen DOT de> <NUTMEGf3ednHM3SOlbp000000a6 AT NUTMEG DOT CAM DOT ARTIMI DOT COM> <20040512154332 DOT GO12030 AT cygbert DOT vinschen DOT de>
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On Wed, May 12, 2004 at 05:43:32PM +0200, Corinna Vinschen wrote:
> On May 12 16:17, Dave Korn wrote:
> >   I reckon you could quote
> > http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap04.html#tag_0
> > 4_11
> > to support the claim that what bash is doing is actually an invalid
> > transformation and should be considered a bug.  That page says 
> > 
> > "A pathname consisting of a single slash shall resolve to the root directory
> > of the process. A null pathname shall not be successfully resolved. A
> > pathname that begins with two successive slashes may be interpreted in an
> > implementation-defined manner, although more than two leading slashes shall
> > be treated as a single slash."
> > 
> >   Therefore translating "/" to "//" has the effect of replacing an
> > unambiguous specs-defined interpretation with an implementation-defined
> > interpretation and is clearly invalid, even though it amounts to a null
> > tranformation on many *nix systems.
> 
> Looking into the bash code, you'll see that this is a well-known fact
> to the bash developers.  This bug just couldn't be easily uncovered,
> since it doesn't result in wrong behaviour on any system so far.  Sheer
> luck that two bugs met each other :-)
> 
I would argue that Corinna's change is a good temporary patch, until bash
is fixed, but that in the long run we should just apply the Posix law.
Allowing // to mean / gives strange results:

 ~> /bin/ls //
alt
bin
<snip>

~> /bin/ls -l //
/bin/ls: //alt: No such file or directory
/bin/ls: //bin: No such file or directory
<snip>

~> /bin/ls "/ . ."
alt
bin
(1.5.9 also screws up on that one, but in a different way)

Pierre


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