code: function (callback) {
      return function (err, stdout, stderr) {
          if (err) {
              throw err;
          } else if (stderr) {
              log('sync error', 'failed with the following output:');
              console.log('\n', stderr, '\n');
          } else {
              log('sync', 'completed successfully');
              log();
              if (callback) callback();
          }
      };
  }
docs: /*
  Report result from rsync.