code: function crawlDirectory(parent, sync) {
      if (sync) {
          return crawlDirectory(parent, sync);
      }
      /* Use `find` if available, because it's fast! */
      return exec('find ' + parent + ' -not -type d').spread(function (stdin) {
          return stdin.split('\n').filter(function (file) {
              return !!file;
          });
      }).fail(function () {
          return crawlDirectoryWithFS(parent, sync);
      });
  }
docs: Crawl a directory for all of it's files!