title: How can I troubleshoot my Perl CGI script?
body: <p>I have a Perl script that isn't working and I don't know how to start narrowing down the problem. What can I do?</p>
  
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  <p>Note: I'm adding the question because I really want to add my very lengthy answer to Stackoverflow. I keep externally linking to it in other answers and it deserves to be here. Don't be shy about editing my answer if you have something to add.</p>