bin/express-cli.js
function exit (code) {
  // flush output for Node.js Windows pipe bug
  // https://github.com/joyent/node/issues/6247 is just one bug example
  // https://github.com/visionmedia/mocha/issues/333 has a good discussion
  function done () {
    if (!(draining--)) _exit(code)
  }

  var draining = 0
  var streams = [process.stdout, process.stderr]

  exit.exited = true

  streams.forEach(function (stream) {
    // submit empty write request and wait for completion
    draining += 1
    stream.write('', done)
  })

  done()
}
function exit (code) {
  // flush output for Node.js Windows pipe bug
  // https://github.com/joyent/node/issues/6247 is just one bug example
  // https://github.com/visionmedia/mocha/issues/333 has a good discussion
  function done () {
    if (!(draining--)) _exit(code)
  }

  var draining = 0
  var streams = [process.stdout, process.stderr]

  exit.exited = true

  streams.forEach(function (stream) {
    // submit empty write request and wait for completion
    draining += 1
    stream.write('', done)
  })

  done()
}
Graceful exit for async STDIO