compare_sites("newsite1.txt", "newsite2.txt")
  if day eq "monday..." # psuedo code

compare_sites("newsite2.txt", "newsite1.txt")
  if day eq "tuesday..." # psuedo code

sub compare_sites {
  my $file1 = shift;
  my $file2 = shift;

  open IN1, $file1;

  while(<IN1>) {
    chomp;
    $newsite1{$_}++;
  } # while

  close IN1;

  open IN2, $file2;

  while(<IN2>) {
    chomp;
    print "$_ is a new site\n" 
      if not defined($newsite1{$_});
  } # while

  close IN2;
} # compare_sites