title: How do I set an environment variable?
body: <p>In bash I can see npm environment variables with <code>npm run env</code>.  <code>USER=brianmackey</code> is one such environment variable.  How can I set an environment variable, say <code>USER=billybob</code>?  </p>
  
  <p>I know I can use <code>npm config set &lt;key&gt; &lt;value&gt; [--global]</code>.  Is key+value always/in any case an environment variable?  Can I set the environment variables in session?</p>