my $num_errors = 0;
foreach my $file (keys %hash1)
{
   if (!exists ($hash2{$file}) )
   {
       print "file: $file doesn't exist in 2nd directory\n";
   }
   elsif ($hash1{$file} ne $hash2{$file})
   {
       print "md5 didn't match for $file\n";
          # meaning that file in 2nd directory is not the 
          # same as the file in 1st directory
       $num_errors++;
   }
}
print "total errors = $num_errors\n";