what does SET NODE_ENV=dev do?
<p>This sounds like a basic question but I couldn't find much information on this on google.</p>

<p>I am following a tutorial <a href="https://scotch.io/tutorials/test-a-node-restful-api-with-mocha-and-chai" rel="nofollow">https://scotch.io/tutorials/test-a-node-restful-api-with-mocha-and-chai</a> on testing node. There is a code in the package.json</p>

<pre><code>"scripts":{
  "start": "SET NODE_ENV=dev &amp;&amp; node server.js",
}
</code></pre>

<p>However, when I run it, I got the error. </p>

<pre><code>WARNING: NODE_ENV value of 'dev ' did not match any deployment config file names.
</code></pre>

<p>So my question is, what does SET NODE_ENV really do? How do you modify it when you want to put it to production?</p>

<p>EDITED on 10/10/2016
I found out from the documentation <a href="https://github.com/lorenwest/node-config/" rel="nofollow">https://github.com/lorenwest/node-config/</a> that the NODE_ENV will look for files in the config folder. so SET NODE_ENV = 'dev' looks for /config/dev.json. It's weird that the error occurs even though the dev.json exist. The app runs like normal so I am just wondering what the error means. </p>