Launch a detached process of node running 'app.js' in the same directory of this script.

launch_detached.js

#!/usr/bin/env node

var spawn = require('child_process').spawn;
var path = require('path');
var nodeBin = process.execPath;
var appjs = path.resolve(__dirname, 'app.js');
var options = { detached: true, stdio: 'ignore', cwd: __dirname };
var child = spawn(nodeBin, [appjs], options);
child.unref();