I Use CPAN.
X Use B::Deparse. https://metacpan.org/pod/B::Deparse
-X Document your shell scripts with pod.
X Know regular expressions.
X Use Regexp::Debugger. https://metacpan.org/pod/Regexp::Debugger
X Write vim plugins in Perl.
+X Document your shell scripts with pod.
X Understand calling context.
X Understand execution phases.
X Understand when to be terse and when to be verbose