title: Add directory to pythonpath via command line
body: <p>I am trying to make a bat file which add its folder to the PYTHONPATH environment variable.</p>
  
  <pre><code>set PYTHONPATH = %PYTHONPATH%; %~dp0
  </code></pre>
  
  <p>I have a PYTHONPATH variable in my system environment variables, but this won't change anything and doesn't add any folder to the variable.</p>
  
  <p>Am I missing something?</p>