title: How to change python env
body: <p>I have a issue where if a python 3 script's shebang line is /usr/bin/env python3 then script will be interpreted with /usr/bin/local/python3</p>
  
  <pre><code>type -P python3
  /usr/local/bin/python3
  </code></pre>
  
  <p>So PATH python3 is /usr/local/bin/python3 but this creates problems where some packages are not available for /usr/local/bin/python3 and I would instead like to use /usr/bin/python3 as default env python3.</p>
  
  <p>Using a alias to set python3 to /usr/bin/python3 can be done but this does not solve the issue. Using Virtualenv if fine but one can not create a virtualenv for every single litte script out there.</p>
  
  <p>type -a shows that there are two python3 defined on my system so there must be a way to change the prefered one:</p>
  
  <pre><code>type -a python3
  python3 is aliased to `/usr/bin/python3'
  python3 is /usr/local/bin/python3
  python3 is /usr/bin/python3
  </code></pre>
  
  <p>How can I change so that env python 3 is /usr/bin/python3?</p>
  
  <p>Best regards</p>