#!/usr/bin/env perl
use warnings;
use strict;
use Tie::File;
use Fcntl 'O_RDONLY';

die "Usage: $0 INPUTFILE WINSIZE\n"
	unless @ARGV==2;
my ($INPUTFILE,$WINSIZE) = @ARGV;

tie my @array, 'Tie::File', $INPUTFILE, mode => O_RDONLY;
$, = " "; $\ = "\n"; # output field/record separators
for my $i (0..@array-$WINSIZE) {
	print @array[$i..$i+$WINSIZE-1];
}