title: How to get a character delimited substring?
body: <p>Some lines of a text file contain a line which starts with an open square bracket, has a variable number of characters followed by a close square bracket and then some further text</p>
  
  <p>For example:</p>
  
  <pre><code> [ABC]  why is the sky green?  
   [DEFG]  Ou sont les Niegedens d'antan?  
   [I can't code C]  (... obviously)
  </code></pre>
  
  <p>How do I get the text between the square brackets?  (I want to <code>printf</code> it)</p>