Re: Testing Success of Opening Pipe in Windows

Although your advice is probably sound (I haven't checked). I don't 
think that posting a link to an illegal copy of Programming Perl is fair 
on the authors, publisher, or the readers of this list.


Lyle

On 12/08/2012 22:11, Tim Bolshaw wrote:
> Chapter 16.3 of /Programming Perl/ has a good basic explanation of how 
> to use pipes in Perl.  (It is available online at 
> http://docstore.mik.ua/orelly/perl2/prog/ch16_03.htm if you do not yet 
> have a copy.)  However, if you are doing extensive and complex 
> processing that relies on pipes, you will may find it easier to use 
> the Perl module IO::Pipe.
>
> Tim.
>
>
> On Mon, Aug 13, 2012 at 3:48 AM, Edwards, Mark (CXO) 
> <[email protected] <mailto:[email protected]>> wrote:
>
>     The typical test for open is ...
>
>     open(HANDLE, "something _/to/_open") or die "Open failed, $!";
>
>     That works on Windows for a file but not a pipe.
>
>     $status=open(PIPE, "hostname |");
>
>     This works and I can read from the pipe but $status is always
>     non-zero so I don't know whether it succeeds or fails.  Even
>     testing for $! or $? doesn't work.  $? is always -1 and $! is
>     always " Inappropriate I/O control operation".  This works as
>     expected on Unix be how do I test for success or failure of
>     opening the pipe?
>
>     The first half of the code below works but I forced a failure on
>     the second half
>
>     Code
>
>     ----------------------------------------
>
>     use warnings;
>
>     use strict;
>
>     my($pid, $pipe);
>
>     print "Open pipe with real file\n";
>
>     $pid=open(PIPE, "hostname |");
>
>     print("OS Error: $!\n");
>
>     print("Child Error: $?\n");
>
>     print("PID: $pid\n");
>
>     print "Host Name:",  <PIPE>;
>
>     close PIPE;
>
>     print "\n\n";
>
>     print "Open pipe with fake file to force a failure\n";
>
>     $pid=open(PIPE, "non_existent_file |");
>
>     print("OS Error: $!\n");
>
>     print("Child Error: $?\n");
>
>     print("PID: $pid\n");
>
>     print "Host Name:",  <PIPE>;
>
>     close PIPE;
>
>     Output
>
>     ----------------------------------------
>
>     =======  Open pipe with real file
>
>     OS Error: Inappropriate I/O control operation
>
>     Child Error: -1
>
>     PID: 10464
>
>     Host Name:MEDWARDS5
>
>     ======  Open pipe with fake file to force a failure
>
>     OS Error: Inappropriate I/O control operation
>
>     Child Error: -1
>
>     PID: 10468
>
>     'non_existent_file' is not recognized as an internal or external
>     command,
>
>     operable program or batch file.
>
>     Host Name:
>
>
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>
>
>
> -- 
> Tim Bolshaw
>
> [email protected] <mailto:[email protected]>
> Mobile: +66-(0)87 072 5009
>
>
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