BUG: /bin/pwd -P doesn't expand all symlinks

BUG: /bin/pwd -P doesn't expand all symlinks

[Mark O'Keefe]

Hi,

While using /bin/pwd -P to expand directories to get the absolute, non-symlinked version of the directory I discovered that this doesn't work on Cygwin as I believe it is meant to work.


$ cd /tmp
$ /bin/pwd -P
/tmp
$ ln -s /home .
$ cd home
$ /bin/pwd -P
/home
$ pwd
/tmp/home
$ mkdir dummy
$ cd dummy
$ pwd
/tmp/home/dummy
$ /bin/pwd -P
/tmp/home/dummy

NOTE:  That last command should have returned "/home/dummy".  It hasn't expanded the parent symbolic link as you would have expected it to do.

For what I'm doing I need the physical path, not the symbolic path (which is what the -P is meant to provide).

Please confirm if I'm correct in my understanding?  I've tested this on Ubuntu and it works as I'd expect it...

Now having to create an alternative approach to get the correct answer while I wait for this to be fixed (assuming it is a bug as I believe it is).

Thanks in advance for any help in resolving this.

Cheers,
Mark.

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RE: /bin/pwd -P doesn't expand all symlinks

[Nellis, Kenneth]

> From: Mark O'Keefe
> 
> Hi,
> 
> While using /bin/pwd -P to expand directories to get the absolute, non-
> symlinked version of the directory I discovered that this doesn't work on
> Cygwin as I believe it is meant to work.
> 
> 
> $ cd /tmp
> $ /bin/pwd -P
> /tmp
> $ ln -s /home .
> $ cd home
> $ /bin/pwd -P
> /home
> $ pwd
> /tmp/home
> $ mkdir dummy
> $ cd dummy
> $ pwd
> /tmp/home/dummy
> $ /bin/pwd -P
> /tmp/home/dummy
> 
> NOTE:  That last command should have returned "/home/dummy".  It hasn't
> expanded the parent symbolic link as you would have expected it to do.
> 
> For what I'm doing I need the physical path, not the symbolic path (which
> is what the -P is meant to provide).
> 
> Please confirm if I'm correct in my understanding?  I've tested this on
> Ubuntu and it works as I'd expect it...
> 
> Now having to create an alternative approach to get the correct answer
> while I wait for this to be fixed (assuming it is a bug as I believe it
> is).
> 
> Thanks in advance for any help in resolving this.
> 
> Cheers,
> Mark.

FWIW, WJJFM:

$ cd /tmp
$ /bin/pwd -P
/tmp
$ ln -s /home .
$ cd home
/tmp/home
$ /bin/pwd -P
/home
$ pwd
/tmp/home
$ mkdir dummy
$ cd dummy
/tmp/home/dummy
$ pwd
/tmp/home/dummy
$ /bin/pwd -P
/home/dummy
$ uname -srvmo
CYGWIN_NT-6.1 2.2.1(0.289/5/3) 2015-08-20 11:42 x86_64 Cygwin
$

--Ken Nellis

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Re: /bin/pwd -P doesn't expand all symlinks

[Mark O'Keefe]

Thanks Ken, you gave me an idea.

$ uname -srvmo
CYGWIN_NT-6.3 2.3.0(0.290/5/3) 2015-09-08 22:33 x86_64 Cygwin

I'm using native symlinks for compatibility. Turns out that if you use the below option to create the symlink you get the behavior I'm seeing. If you don't use this it works correctly. Guess the issue is in understanding native symlinks... Is that expected? I know I don't like it ;-)

CYGWIN=winsymlinks:nativestrict

Cheers,
Mark.

On 23 Oct 2015, at 11:35 PM, Nellis, Kenneth <Kenneth.Nellis@xerox.com> wrote:

>> From: Mark O'Keefe
>> 
>> Hi,
>> 
>> While using /bin/pwd -P to expand directories to get the absolute, non-
>> symlinked version of the directory I discovered that this doesn't work on
>> Cygwin as I believe it is meant to work.
>> 
>> 
>> $ cd /tmp
>> $ /bin/pwd -P
>> /tmp
>> $ ln -s /home .
>> $ cd home
>> $ /bin/pwd -P
>> /home
>> $ pwd
>> /tmp/home
>> $ mkdir dummy
>> $ cd dummy
>> $ pwd
>> /tmp/home/dummy
>> $ /bin/pwd -P
>> /tmp/home/dummy
>> 
>> NOTE:  That last command should have returned "/home/dummy".  It hasn't
>> expanded the parent symbolic link as you would have expected it to do.
>> 
>> For what I'm doing I need the physical path, not the symbolic path (which
>> is what the -P is meant to provide).
>> 
>> Please confirm if I'm correct in my understanding?  I've tested this on
>> Ubuntu and it works as I'd expect it...
>> 
>> Now having to create an alternative approach to get the correct answer
>> while I wait for this to be fixed (assuming it is a bug as I believe it
>> is).
>> 
>> Thanks in advance for any help in resolving this.
>> 
>> Cheers,
>> Mark.
> 
> FWIW, WJJFM:
> 
> $ cd /tmp
> $ /bin/pwd -P
> /tmp
> $ ln -s /home .
> $ cd home
> /tmp/home
> $ /bin/pwd -P
> /home
> $ pwd
> /tmp/home
> $ mkdir dummy
> $ cd dummy
> /tmp/home/dummy
> $ pwd
> /tmp/home/dummy
> $ /bin/pwd -P
> /home/dummy
> $ uname -srvmo
> CYGWIN_NT-6.1 2.2.1(0.289/5/3) 2015-08-20 11:42 x86_64 Cygwin
> $
> 
> --Ken Nellis
> 
> --
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> 

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Re: BUG: /bin/pwd -P doesn't expand all symlinks

[Andrey Repin]

Greetings, Mark O'Keefe!

> While using /bin/pwd -P to expand directories to get the absolute,
> non-symlinked version of the directory I discovered that this doesn't work
> on Cygwin as I believe it is meant to work.


> $ cd /tmp
> $ /bin/pwd -P
> /tmp
> $ ln -s /home .
> $ cd home
> $ /bin/pwd -P
> /home
> $ pwd
> /tmp/home
> $ mkdir dummy
> $ cd dummy
> $ pwd
> /tmp/home/dummy
> $ /bin/pwd -P
> /tmp/home/dummy

> NOTE:  That last command should have returned "/home/dummy".  It hasn't
> expanded the parent symbolic link as you would have expected it to do.

> For what I'm doing I need the physical path, not the symbolic path (which is what the -P is meant to provide).

> Please confirm if I'm correct in my understanding?  I've tested this on
> Ubuntu and it works as I'd expect it...

> Now having to create an alternative approach to get the correct answer
> while I wait for this to be fixed (assuming it is a bug as I believe it is).

> Thanks in advance for any help in resolving this.

There's some juju with native symlink expansion going on. I vaguely recall
that it was done for speed. But the results really seems non-expected.

C:\arc is a symlink to the \\daemon1\arc shared directory.

$ cd /c/arc/
anrdaemon@daemon2:/c/arc
$ /bin/pwd.exe -P
//DAEMON1/arc
anrdaemon@daemon2:/c/arc
$ /bin/readlink.exe -fe .
//DAEMON1/arc

All is well.

anrdaemon@daemon2:/c/arc
$ cd images/
anrdaemon@daemon2:/c/arc/images
$ /bin/pwd.exe -P
/c/arc/images
anrdaemon@daemon2:/c/arc/images
$ readlink -fe .
/c/arc/images

Not expected. But here we are going to real surprise:

anrdaemon@daemon2:/c/arc/images
$ readlink -fe $(pwd)
//DAEMON1/arc/images


-- 
With best regards,
Andrey Repin
Friday, October 23, 2015 17:46:32

Sorry for my terrible english...


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