while( my($lk,$lv) = each %$loc_file ) {
    my $flag = 0;
    while( my($rk,$rv) = each %$rem_file ) {
      if($lk eq $rk) {
        # .. do a "get" or "put" if necessary
        $flag = 1;
      }
    }
    if ( $flag == 0 ) {
      .. #
    }
  }
  while( my($rk,$rv) = each %$rem_file ) {
    my $flag = 0;
    while( my($lk,$lv) = each %$loc_file ) {
      # same as above, but in other direction...
    }
  }