#!/usr/bin/env perl 
#===============================================================================
#
#         FILE: zip.pl
#
#        USAGE: ./zip.pl input1 input2 output
#
#  DESCRIPTION: Zip 2 input files into one output file, looping the
#  shorter one.
#
# REQUIREMENTS: Path::Tiny
#        NOTES: See http://www.perlmonks.org/?node_id=1191418
#===============================================================================

use strict;
use warnings;
use Path::Tiny;

my @in = (
    path ($ARGV[0]),
    path ($ARGV[1])
);
my $out = $ARGV[2];

my @first  = $in[0]->lines;
my @second = $in[1]->lines;
my $max = $#first > $#second ? $#first : $#second;

open my $outfh, '>', $out or die "Cannot open $out for writing: $!";
for (0 .. $max) {
    print $outfh $first[$_ % @first] . $second[$_ % @second]
}