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Date: Fri, 13 Jul 2012 16:31:25 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: test -f //dot
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On Jul 13 13:27, Adam Dinwoodie wrote:
> Paul Keir wrote:
> >While running configure on llvm I get a hang on:
> >
> >...
> >checking for Graphviz... echo Graphviz
> >checking for dot...
> >
> >The configure script has a line starting:
> >if { test -f "$as_dir/$ac_word$ac_exec_ext" && ...
> >
> >The problem occurs when $as_dir is /
> >
> >test -f //dot
> 
> This will be to do with how Windows and Linux handle UNC paths. On Windows and                                                                               Cygwin, //dot refers to a network share called "dot". On Linux (or at least the
> RHEL6.2 system I just checked) //dot is a different way of expressing /dot.
> 
> On RHEL:
> 
>     # mkdir /dot
>     # [[ /dot -ef //dot ]] && echo They look the same to me
>     They look the same to me
> 
> On Cygwin:
> 
>     $ mkdir /dot
>     $ [[ /dot -ef //dot ]] || echo "But Cygwin thinks they're different"
>     But Cygwin thinks they're different
> 
> >...also hangs (at least 15 mins.). I tested it on Linux and another-
> >cygwin machine, and test returns promptly there.
> 
> So what's the difference between the two Cygwin setups? The versions of
> cygwin1.dll are probably most useful, although bear in mind "x worked with some
> old version of Cygwin" tends to gather little sympathy unless the behaviour is
> clearly a bug -- this isn't. At least to me.

Neither in terms of POSIX compatibility.  See the next to last paragraph
of the "Pathname Resolution" chapter in the Open Group specs:

http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_12


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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