Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I’ve been poring over IPC::Run documentation, have tried running several of the code samples in the docs, and am having no joy. I’m a Perl newbie, and I’m sure I’m doing something wrong. But 2 hours of poking and starting and Googleing haven't helped me. May I impose for a few quick questions?

From http://search.cpan.org/~rsod/IPC-Run-0.79/lib/IPC/Run.pm, I copied and ran (after adding the ‘use’ command) the following: 

use IPC::Run qw (start pump finish );
## Build the harness, open all pipes, and launch the subprocesses

my $h = start \@cat, \$in, \$out, \$err ;

$in = "first input\n" ;


## Now do I/O.  start() does no I/O.

pump $h while length $in ;  ## Wait for all input to go


## Now do some more I/O.

$in = "second input\n" ;

pump $h until $out =~ /second input/ ;


## Clean up

finish $h or die "cat returned $?" ;

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When I execute this, I get a clean compile on Windows XP with the latest ActivePerl, but get this error at execution time:

Command '' not found in C:\Perl\bin\, C:\WINDOWS\system32, C:\WINDOWS, C:\WINDOWS\System32\Wbem, C:\Program Files\Common Files\Roxio Shared\DLLShared, C:\Program Files\Sonic\MyDVD, C:\Sun\AppServer\jdk\bin, C:\Program Files\Sonic\MyDVD at C:/Program Files/eclipse/workspace/Wizard/run.pl line 4

I can’t figure out what command it is looking for. At a high level I know that I need to feed the ‘start’ some command to run. But I didn’t see an example of how to do this. Do I place a command into the ‘@cat’ array? What would I use to make this example work on Windows XP?

Many thanks!

tl

2005-02-18 Janitored by Arunbear - added code tags, as per Monastery guidelines

Replies are listed 'Best First'.
Re: IPC::Run syntax question
by Corion (Patriarch) on Feb 13, 2005 at 20:38 UTC

    My version of IPC::Run (0.78) has the following example in the documentation:

    ## First,a command to run:
   my @cat = qw( cat ) ;

## Using run() instead of system():
   use IPC::Run qw( run timeout ) ;

   run \@cmd, \$in, \$out, \$err, timeout( 10 ) or die "cat: $?"

   # Can do I/O to sub refs and filenames, too:
   run \@cmd, "in.txt", \&out, \&err or die "cat: $?"
   run \@cat, "in.txt", '>>', "out.txt", '2>>', "err.txt" ;

   # Redirecting using psuedo-terminals instad of pipes.
   run \@cat, '<pty<', \$in,  '>pty>', \$out_and_err ;

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    so, yes, @cat needs to be filled with the command and the arguments of the thing you want to run.

    But if you're trying some basic things, why dabble with IPC::Run if the plain system() call or backticks can do your work already? What do you want to do?

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[d/l]
      Hi

      Thanks very much for the reply. Putting the command and its arguments into an array that becomes the first argument to 'run' is now obvious; thanks for pointing that out!

      I wish I could use something simpler than IPC::Run, but I don't think I can (please tell me I'm wrong).

      I need to run a program, and then do things with the program's output. So, system() (which doesn't allow this) isn't the right tool.

      Worse, I need to feed responses to the program as it runs. Backticks doesn't support this.

      I had initially looked at Open2(), but that didn't work on Windows XP. So, I'm trying IPC::Run, as it SEEMS to be the best solution.

      I'd very much value the opinion of others with more Perl experience than me (which, at this point, includes many house plants).

      Thanks! tl

[reply]
        Greetings, esteemed monks!

        I assume you also looked into open3? _________________________________________________________________________________
        Without me, it's just aweso
[reply]

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