code: function bindToFile(filePath, cb) {
  	// resolve the path and shorten it to avoid long-path bind errors
  	// NOTE: only do so on non-windows systems
  
  	if (process.platform !== 'win32') {
  		filePath = pathRelative(process.cwd(), pathResolve(filePath));
  	}
  
  	function callback(error) {
  		server.removeListener('error', callback);
  
  		if (error) {
  			if (error.code === 'EADDRINUSE') {
  				error.message =
  					filePath + ' already exists. Perhaps the server did not shut down ' +
  					'cleanly. Try removing the file and starting again. (' + error.code + ')';
  			} else {
  				error.message = 'Error while binding to ' + filePath + ' (' + error.code + ')';
  			}
  
  			return cb(error);
  		}
  
  		logger.notice('HTTP Server bound to', filePath);
  
  		return cb();
  	}
  
  	// listen() can throw, despite the error listener
  	// this happens in cluster mode if the stdio channels have been closed by the master
  
  	server.on('error', callback);
  
  	try {
  		server.listen(filePath, function (error) {
  			if (error) {
  				return callback(error);
  			}
  
  			fs.chmod(filePath, parseInt('777', 8), callback);
  		});
  	} catch (error) {
  		// listen() can throw, despite the error listener
  		// this happens in cluster mode if the stdio channels have been closed by the master
  
  		setImmediate(function () {
  			callback(error);
  		});
  	}
  }
docs: functions for listening on port or socket file