code: function respawn() {
    var argv = process.argv;
    var child = child_process.spawn(argv[0], argv.slice(1).concat('--child-flag'));
    child.stderr.pipe(process.stderr);
    process.stdin.pipe(child.stdin);
    child.stdout.on('data', function(data) {
      if (~data.toString('utf-8').indexOf('Currently running fis3')) {
        return;
      }
      process.stdout.write(data);
    });
    child.on('exit', function(code, signal) {
      process.on('exit', function() {
        if (signal) {
          process.kill(process.pid, signal);
        } else {
          process.exit(code);
        }
      });
    });
    return child;
  }
docs: 当监听到 fis-conf.js 文件变化的时候，kill self 重启一个新进程。