coroutines

sync.js

var co = require('co');
var proc = require('child_process')

function exec(command) {
  var p = new Promise(function (resolve, reject) {
    proc.exec(command, function (err, stdout, stderr) {
      if (err) {
        console.log(stderr);
      } else {
        console.log(stdout)
      }
      setTimeout(function () {
        resolve(true)
      }, 3000)
    });
  });

  return p;
}

co(function* () {
  var a = yield exec('sudo service postgresql stop')
  var b = yield exec('sudo service nginx stop')
  var c = yield exec('sudo service redis-server stop')
});