app_auth.js

#!/usr/bin/env node

var inquirer = require("inquirer"),
    request = require("request"),
    qs = require('querystring'),
    fs = require('fs');

var request_token_url = 'https://api.twitter.com/oauth/request_token',
    access_token_url = 'https://api.twitter.com/oauth/access_token';

var questions0 = [
  {
    type: "input",
    name: "consumer_key",
    message: "Consumer Key: "
  },
  {
    type: "input",
    name: "consumer_secret",
    message: "Consumer Secret: "
  }
];

var questions1 = [
  {
    type: "input",
    name: "pin",
    message: "Pin: "
  }
];

inquirer.prompt( questions0, function( answers0 ) {
  answers0.oauth_callback = 'oob';

  request.post({url: request_token_url, oauth: answers0}, function (e, r, body){

    var req_data = qs.parse(body);

    var uri = 'https://api.twitter.com/oauth/authenticate';
    uri += '?' + qs.stringify({oauth_token: req_data.oauth_token});

    console.log('Please visit: ' + uri);

    inquirer.prompt( questions1, function( answers1 ) {

      oauth = {
        consumer_key: answers0.consumer_key,
        consumer_secret: answers0.consumer_secret,
        token: req_data.oauth_token,
        token_secret: req_data.oauth_token_secret,
        verifier: answers1.pin
      };

      request.post({url:access_token_url, oauth:oauth}, function (e, r, body) {
        perm_data = qs.parse(body);

        var env_text = '';
        env_text += 'CONSUMER_KEY=' + answers0.consumer_key + "\n";
        env_text += 'CONSUMER_SECRET=' + answers0.consumer_secret + "\n";
        env_text += 'ACCESS_TOKEN=' + perm_data.oauth_token + "\n";
        env_text += 'ACCESS_TOKEN_SECRET=' + perm_data.oauth_token_secret;

        console.log(env_text);

        fs.writeFile(".env", env_text, function(err) {
            if(err) {
                console.log(err);
            } else {
                console.log("The auth keys have been saved to .env!");
            }
        });
      });

    });

  });
});