title: linux bash script running multiple python
body: <p>I have 2 python scripts a.py and b.py
  and I want to write a bash script that will load a.py and not run b.py until a.py is done doing it's thing.
  simplistically </p>
  
  <pre><code>#!/usr/bin/env bash
  python a.py
  python b.py
  </code></pre>
  
  <p>but this is naive, a check to see if a.py is done... how do I do that?</p>