To use RSA as an example, instead of trying to use a PGP module from CPAN, I use the gpg command-line program, write its output to a file, and use that.
It's not as graceful, but it is also highly compatible with just OS packages.
What makes you choose Perl over bash/sh then, if it's working as a "glue" between actual binaries? I imagine the text processing things it excels at?
I feel comfortable with parentheses, curly braces, freeform whitespace, etc., if/else, do/while, foreach, etc., and that's how I write my Perl.
I sometimes call it "PHP style Perl", because most of the code i write can be copied and pasted almost verbatim between PHP and Perl, and I use this to my advantage.
I don't use PHP a lot, but I do find it one of the most convenient ways to duct-tape things to a web server.
On the whole, I've settled on a strategy of writing most code in such a way that it could have been written (with perfect foresight of the future) 20 years and go and have worked the whole time.
I think of it as exploiting the Lindy Effect to my advantage. :)