title: How to start pm2 process with DEBUG option
body: <p>I have an express app that I start in terminal with following command to enable debug logs in it:</p>
  
  <pre><code>DEBUG=custom:* npm start (on Ubuntu)
  SET DEBUG=custom:* &amp; npm start (on Windows)
  </code></pre>
  
  <p>On production server, I start app with PM2 using following command:</p>
  
  <pre><code>pm2 start bin/www -i 0
  </code></pre>
  
  <p>But this does not enable the <code>debug</code> logs in my code, so the debug statements are not added to the logs, only <code>console.error()</code> are added to the log files. How can I pass the <code>DEBUG=custom:*</code> option while starting my app with PM2?</p>