text: const spawn = require('child_process').spawn;
  var fs = require('fs');
  var path = require('path');
  var net = require('net');
  
  fs.open(path.join(__dirname, 'test.txt'), 'a', (err, fd) => {
      if (err) throw err;
      var server = net.createServer((socket) => {
          socket.write(JSON.stringify({
              fd: fd
          }));
          // socket.end();
          // server.close();
      }).listen(4000, () => {
          // var child = spawn(process.argv[0], [path.join(__dirname, 'childProcessClient.js')]);
          // child.on('exit', () => {
          //     console.log('child process exited.');
          // });
      });
  });