#! /usr/bin/perl

use	File::Copy;

my	$from = "/var/local/backup/from/";
my	$to = "/var/local/backup/to/";

opendir (H1, $from) || die ("error: cannot read input directory");
opendir (H2, $to) || die ("error: cannot read output directory");

my	@files1 = readdir (H1);
my	%files2 = map { $_ => 1 } readdir (H2);

closedir (H1);
closedir (H2);

foreach $file (@files1)
{
	if ($file != '.' && $file != '..')
	{
		my	$i = 0;

		while ($files2{"$file.$i"})
		{
			$i = $i + 1;
		}

		if ($i == 0 || -s "$from/$file" != -s ("$to/$file." . ($i - 1)))
		{
			copy ("$from/$file", "$to/$file.$i");
			print "backup $file as $file.$i\n";
		}
	}
}