title: How to launch IPython while showing line numbers at the prompt?
body: <p>I launch IPython in a script via: <code>start_ipython(config=cfg)</code> . <code>cfg</code> currently consists of modifications to <code>HistoryAccessor.hist_file</code>, <code>InteractiveShell.banner1</code>... but I can't find anything in the <a href="https://ipython.readthedocs.io/en/stable/config/options/terminal.html" rel="nofollow noreferrer">documentation</a> which relates to line numbers at the prompt. Currently, the prompt appears without line numbers as shown. IPython 7.2.0</p>
  
  <p><a href="https://i.stack.imgur.com/onu9b.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/onu9b.png" alt="enter image description here"></a></p>
  
  <p>If I run IPython from the command line (as opposed to from the above script), the line numbers appear as expected
  <a href="https://i.stack.imgur.com/wMBGu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wMBGu.png" alt="enter image description here"></a></p>