Create app.js

app.js

process.on('SIGINT',  function(){ console.log("SIGINT");  terminate() });
process.on('SIGTERM', function(){ console.log("SIGTERM"); terminate() });

var string = "a";

var terminate = function(){
  console.log("shuting down...");
  string = "b";

  setTimeout(function(){
    console.log("Terminated!");
    process.exit();
  }, 1000 * 5);
}

setInterval(function(){
  console.log(string);
}, 500)