Function copyFile

debug.js:103–107

(oldname, newname, callback)

	const PIDNAME = FILENAME.replace(/\.js$/, '.pid');

	function copyFile(oldname, newname, callback) {
		var writer = Fs.createWriteStream(newname);
		callback && writer.on('finish', callback);
		Fs.createReadStream(oldname).pipe(writer);
	}

	function app() {