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

Dear Masters,
I have 3 Perl codes, let's call them: foo.pl, bar.pl, tins.pl. All of them would run sequentially starting from foo.pl. So normally I would do this three lines manually, waiting for each code to finish to get to the final result. 
perl foo.pl param1 > output1.txt
perl bar.pl output1.txt > output2.txt
perl tins.pl output2.txt > final_result.txt

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My question is, how can one writes a single Perl script that would run those three codes automatically?

---
neversaint and everlastingly indebted.......

Replies are listed 'Best First'.
Re: Automatically running series of Perl programs
by philcrow (Priest) on Mar 09, 2006 at 14:58 UTC
    There are several ways including using backticks `` around each command. Most people probably prefer using the system command. You could also open each program on a file handle: 
    open PROG "perl foo.pl param1 | " or die "...";

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    Then you can handle the io.

    You could also simplify your three steps into one and write a shell script (did I really suggest that?): 

    perl foo.perl param1 | perl bar.pl | perl tins.pl > result.txt

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    Phil

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      Yeah, I think you really did suggest that. Furthermore, I'd suggest a shell script, too. I usually use Perl scripts rather than shell scripts even when a shell script would do quite well enough, but this really strikes me as something simple enough that using Perl is complete overkill and a waste of time, unless running the three other scripts in sequence is part of a larger algorithm somehow.

      print substr("Just another Perl hacker", 0, -2);
      		 - apotheon
      CopyWrite Chad Perrin

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Re: Automatically running series of Perl programs
by SamCG (Hermit) on Mar 09, 2006 at 14:59 UTC
    Does: 
    system ("perl foo.pl param1 > output1.txt");
system ("perl bar.pl output1.txt > output2.txt");
system ("perl tins.pl output2.txt > final_result.txt");

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    not work?
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Re: Automatically running series of Perl programs
by radiantmatrix (Parson) on Mar 09, 2006 at 17:12 UTC

    Well, this is probably easier done as a shell script, but since you asked: 

    use strict;
use warnings;

my %ops = (
    'foo'  => ['param1','output1.txt'],
    'bar'  => ['output1.txt','output2.txt'],
    'tins' => ['output2.txt','final_result.txt'],
);

foreach (qw[foo bar tins]) {
    my $outfile = pop @{ $ops{$_} };
    system( $^X, $_.'.pl', @{ $ops{$_} }, '>', $outfile); # $^X is per
+l interp.
}

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    <-radiant.matrix->
    A collection of thoughts and links from the minds of geeks
    The Code that can be seen is not the true Code
    I haven't found a problem yet that can't be solved by a well-placed trebuchet
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Re: Automatically running series of Perl programs
by duff (Parson) on Mar 09, 2006 at 16:13 UTC

    Another option in the TMTOWTDI department is to just stick those lines in a shell script (if on a unixish OS) or a batch file (if on a windowsish OS) or whatever is appropriate for you OS.

    duff

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Re: Automatically running series of Perl programs
by smokemachine (Hermit) on Mar 09, 2006 at 15:58 UTC
    can't you use something like this? 
    perl foo.pl param1 | perl bar.pl | perl tins.pl > final_result.txt

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    like: 
    perl -e 'print "test"' | perl -ne 'print "--$_"' | perl -ne 'print "$_
+-- \n"' > final_result.txt

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