can't access .env with node-config

Question

I want to access my local .env file with node-config, but node-config always accesses my system env.

local .env means which env file exists on my project folder.

// development.js
require('dotenv').config();

module.exports = {
  port: 4000,
  version: 'v1', 
};

// production.js
require('dotenv').config();

module.exports = {
  port: 8000,
  version: 'v1', 
};

// app.js
require('dotenv').config();
const config = require('config');

console.log(config.util.getEnv('NODE_ENV'));


// .env
NODE_ENV=production

I set NODE_ENV=production at my local .env file. But when I console log always see development, but expected production.

Thats why i can't change configuration development to production. Means i can't access production port and other info. I also use dotenv but don't get my expected result.

Node -> 10.6.0
npm -> 6.1.0
config -> 2.0.1