open(CONFIG, "+<c:/blah.txt" ) or die "Can't open blah.txt: $!";
  my @configfile = <CONFIG>;
  seek CONFIG, 0, 0;  # go to start of file for overwrite
  truncate CONFIG, 0; # get rid of old file
  foreach my $configfile (@configfile) {
      $configfile =~ s/serverport 111$/serverport $port/;
      print CONFIG $configfile or die $!;
  }
  close(CONFIG);
  close(STDERR);