CODEWITHSUNDEEP
perlpipe
Sam Adamsh
Sam Adamsh

Reputation: 3391

how to pipe output from a perl script to another via commandline or via a script

I have on a windows machine (with perl interpreter on environmental path) the command : 

 perl script1.pl | perl script2.pl

and the contents of script one are just: 

  print "AAA";

and the contents of script 2 is just:

  $r = shift;
  print $r;

And the command doesn't pipe correctly. How do you do this? Also, if you were to do it with a Filehandle, how would you run a perl script from another script concurrently. The following doesn't work: 

    open F, '| perl script2.pl AAA';

Upvotes: 4

Views: 2478

Answers (2)

Greg Bacon
Greg Bacon

Reputation: 139531

Remember that shift in your main program removes elements from the special array @ARGV that holds the current invocation’s command-line arguments.

Write script2 as a filter

#! perl

while (<>) {
  print "$0: ", $_;
}

or even

#! perl -p
s/^/$0: /;

To set up the pipeline from script1, use

#! perl

use strict;
use warnings;

open my $fh, "|-", "perl", "script2.pl"
  or die "$0: could not start script2: $!";

print $fh $_, "\n" for qw/ foo bar baz quux /;

close $fh or die $! ? "$0: close: $!"
                    : "$0: script2 exited $?";

Multi-argument open bypasses the shell’s argument parsing—an excellent idea on Windows. The code above assumes both scripts are in the current directory. Output:

script2.pl: foo
script2.pl: bar
script2.pl: baz
script2.pl: quux

Upvotes: 1

tuxuday
tuxuday

Reputation: 3037

You should be reading from STDIN, shift manipulates command-line arguments.

The following snippet explains it.

cat script1.pl
print "AAA";

cat script2.pl
print <STDIN>;

Upvotes: 1

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