title: Grep/bash regex - combination of alternation and set of numbers
body: <p>I need to end up matching any of the following:
  <code>AD-123, ad-123, AD123, and ad123</code></p>
  
  <p>So far what I have is </p>
  
  <p><code>| grep -oP 'AD-|ad-|AD|ad'[0-9]\+)</code></p>
  
  <p>but that only matches the letters and completely ignores the numbers, and I can't figure out a bash-friendly way to do this. </p>
  
  <p>Context/use case: prepare-commit-msg githook, I want to take the Jira ticket from the branch name and add it to any commit message. The Jira ticket would be written in one of the ways described above under a branch naming convention of feature/version/ticker-keywords (example feature/1.1.3/ad-123-some-branch) </p>