Getopt::Long::GetOptions(
   'u=s' => \$user,
   'p=s' => \$passwd,
   's=s' => sub {
      local *_ = \$_[1];
      /^([^:]+):(\d+)$/
      or die("Invalid format for option s.\n");
      $host = $1;
      $port = $2;
   },
   'help' => \$help,  # Will also handle -h
) or error_detect("3 Invalid commmand line options.");

if ($help) {
   die("usage: ...\n");
}