use List::MoreUtils qw(uniq);

open(HD,"File") or die ("Cant open");
$text=<HD>;
chomp $text;

my $n    = 6;
my $back = $n - 1;
my @array = unpack qq{(a$n X$back)*}, $text;

@unpacked=uniq @array;

for($i=0;$i<=$#unpacked-$back;$i++)
{
	$pattern= $unpacked[$i];
	$offset = 0;
	print "\n$pattern ($n)\n";
	print '~' x $n,"\n";
	
	$pos=index $text,$pattern,$offset;

	while ($pos != -1) 
	{	
		print $pos+1," to ",$pos+$n,"\n";
		$offset = $pos + 1;
    	$pos = index($text, $pattern, $offset);
	}
}