Every so often, I need to find out whether I have a certain Perl module installed. Usually it’s either because of a security alert, or because I’m wondering how much of a pain it would be to install some package that has Some::Obscure::Module as a prerequisite.
I don’t know how y’all do it, what with the plethora of package-management utilities out there, but one way that works for sure is simply:
perl -MSome::Module -e ''
If this command succeeds, that means Perl successfully loaded Some::Module, then executed the (empty) script, printing nothing. If Some::Module is missing, it’ll print an error message and fail.
This is short enough that it should be aliased, but I haven’t gotten around to that yet.