executing external program question

echoangel911 has asked for the wisdom of the Perl Monks concerning the following question:

Hi all, I need help/ideas on how to do this. I have this command in my perl script where I call this external program.

$tcl = 'load $gdsfile; $command1; $command2; etc ...';

$output = `abctool -shell $tcl`;
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I found out that I need to generate some extra commands on the run while running the tcl code. Is there anyway I can execute the 'load $gdsfile' section and keep the program running? I do not want to rerun the whole command again since the 'load $gdsfile' code takes 1 hour to run. thanks

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Re: executing external program question by lin0 (Curate) on Jun 19, 2007 at 15:33 UTC
Hi echoangel911, There is more than one way to do it ;-) For instance, you could use IPC::Open3 following recommendations such as the ones you will find in Re: IPC::Open3 woes or in the Perl Journal Article Perl and Inline Octave Code. Another option is using IPC::Run Cheers, lin0	[reply]
Re: executing external program question by suaveant (Parson) on Jun 19, 2007 at 15:23 UTC
You question isn't exactly clear, but maybe you want Expect.pm... it allows you to interact with a command line program like Tcl expect does - Ant - Some of my best work - (1 2 3)	[reply]
Re: executing external program question by odrm (Novice) on Jun 19, 2007 at 15:33 UTC
Two rather different approaches spring to mind: Save the output from the long-running job to a temporary file, and read from that when you need the results Launch the long-running job as a sub-process of your Perl program, and use one of the many IPC (inter-process-communication) methods Alternative (a) is a lot easier to implement provided that you can run the 1hr+ job before the rest of the code. `Data::Dumper` or `Storable` are two useful modules if you want a "perlish" format to the results data. Alternative (b) may allow you to interact with the long-running job, but it is non-trivial to avoid all of the potential pit-falls of concurrent programming. You may want to investigate the `IPC::Open2` module for this alternative.	[reply] [d/l] [select]