public static  void main(String[] args) throws Exception 
{
    if (args.length <  1) {
      System.out.println
        ("Usage: Crawl < urlDir > [-dir d] [-threads n] [-depth i] [-topN N]");
      return;
    }
    Configuration conf = NutchConfiguration.create();
    conf.addResource("crawl-tool.xml");
    JobConf job = new NutchJob(conf);
    Path rootUrlDir = null;
    Path dir = new Path("crawl-" + getDate());
    int threads = job.getInt("fetcher.threads.fetch", 10);
    int depth = 5;
    long topN = Long.MAX_VALUE;
    for (int i = 0; i <  args.length; i++) {
      if ("-dir".equals(args[i])) {
        dir = new Path(args[i+1]);
        i++;
      } else if ("-threads".equals(args[i])) {
        threads = Integer.parseInt(args[i+1]);
        i++;
      } else if ("-depth".equals(args[i])) {
        depth = Integer.parseInt(args[i+1]);
        i++;
      } else if ("-topN".equals(args[i])) {
          topN = Integer.parseInt(args[i+1]);
          i++;
      } else if (args[i] != null) {
        rootUrlDir = new Path(args[i]);
      }
    }
    FileSystem fs = FileSystem.get(job);
    if (LOG.isInfoEnabled()) {
      LOG.info("crawl started in: " + dir);
      LOG.info("rootUrlDir = " + rootUrlDir);
      LOG.info("threads = " + threads);
      LOG.info("depth = " + depth);
      if (topN != Long.MAX_VALUE)
        LOG.info("topN = " + topN);
    }
    Path crawlDb = new Path(dir + "/crawldb");
    Path linkDb = new Path(dir + "/linkdb");
    Path segments = new Path(dir + "/segments");
    Path indexes = new Path(dir + "/indexes");
    Path index = new Path(dir + "/index");
    Path tmpDir = job.getLocalPath("crawl"+Path.SEPARATOR+getDate());
    Injector injector = new Injector(conf);
    Generator generator = new Generator(conf);
    Fetcher fetcher = new Fetcher(conf);
    ParseSegment parseSegment = new ParseSegment(conf);
    CrawlDb crawlDbTool = new CrawlDb(conf);
    LinkDb linkDbTool = new LinkDb(conf);
    Indexer indexer = new Indexer(conf);
    DeleteDuplicates dedup = new DeleteDuplicates(conf);
    IndexMerger merger = new IndexMerger(conf);
    // initialize crawlDb
    injector.inject(crawlDb, rootUrlDir);
    int i;
    for (i = 0; i <  depth; i++) {             // generate new segment
      Path segment = generator.generate(crawlDb, segments, -1, topN, System
          .currentTimeMillis());
      if (segment == null) {
        LOG.info("Stopping at depth=" + i + " - no more URLs to fetch.");
        break;
      }
      fetcher.fetch(segment, threads, org.apache.nutch.fetcher.Fetcher.isParsing(conf));  // fetch it
      if (!Fetcher.isParsing(job)) {
        parseSegment.parse(segment);    // parse it, if needed
      }
      crawlDbTool.update(crawlDb, new Path[]{segment}, true, true); // update crawldb
    }
    if (i  > 0) {
      linkDbTool.invert(linkDb, segments, true, true, false); // invert links
      if(indexes != null) {
        // Delete old indexes
        if (fs.exists(indexes)) {
          LOG.info("Deleting old indexes: " + indexes);
          fs.delete(indexes, true);
        }
        // Delete old index
        if (fs.exists(index)) {
          LOG.info("Deleting old merged index: " + index);
          fs.delete(index, true);
        }
      }
      // index, dedup & merge
      FileStatus[] fstats = fs.listStatus(segments, HadoopFSUtil.getPassDirectoriesFilter(fs));
      indexer.index(indexes, crawlDb, linkDb, Arrays.asList(HadoopFSUtil.getPaths(fstats)));
      if(indexes != null) {
        dedup.dedup(new Path[] { indexes });
        fstats = fs.listStatus(indexes, HadoopFSUtil.getPassDirectoriesFilter(fs));
        merger.merge(HadoopFSUtil.getPaths(fstats), index, tmpDir);
      }
    } else {
      LOG.warn("No URLs to fetch - check your seed list and URL filters.");
    }
    if (LOG.isInfoEnabled()) { LOG.info("crawl finished: " + dir); }
}