#!/usr/bin/perl
use strict;
use warnings;
use IPC::Open2;

my $pid;
eval {
    $pid = open2(\*OUT, \*IN, qw(perl -ne), '$|=1; print if /hello/i');
};
if ($@ and $@ =~ /^open2:/) {
    die "$@:$!\n";
}

my $sometext = <<END;
Hello, World!
END
print IN $sometext;
close IN;

# read/print line by line, so we see the output
while (<OUT>) {
    print ":: $_";
}