final CmdLineParser parser = new CmdLineParser(options);
        try {
            parser.parseArgument(args);
        } catch (final CmdLineException e) {
            System.err.println(e.getMessage());
            System.err.println("java " + Crawler.class.getCanonicalName() + " [options...] arguments...");
            parser.printUsage(System.err);
            return;
        }