index.js

var child_process = require('child_process');

// daemonize ourselves
module.exports = function(opt) {
 // we are a daemon, don't daemonize again
 if (process.env.__daemon) {
 return process.pid;
 }

 var args = [].concat(process.argv);

 // shift off node
 args.shift();

 // our script name
 var script = args.shift();

 opt = opt || {};
 var env = opt.env || process.env;

 // the child process will have this set so we can identify it as being daemonized
 env.__daemon = true;

 // start ourselves as a daemon
 module.exports.daemon(script, args, opt);

 // parent is done
 return process.exit();
};

// daemonizes the script and returns the child process object
module.exports.daemon = function(script, args, opt) {

 opt = opt || {};

 var stdout = opt.stdout || 'ignore';
 var stderr = opt.stderr || 'ignore';

 var env = opt.env || process.env;
 var cwd = opt.cwd || process.cwd();

 var cp_opt = {
 stdio: ['ignore', stdout, stderr],
 env: env,
 cwd: cwd,
 detached: true
 };

 // spawn the child using the same node process as ours
 var child = child_process.spawn(process.execPath, [script].concat(args), cp_opt);

 // required so the parent can exit
 child.unref();

 return child;
};