Perl broken on El Capitan

I switched to El Capitan about a year ago. I have need to run Perl scripts periodically, and they ran fine before the upgrade. Now, they won't run at all. I get a lot of various errors. For example, one script that I ran previously gets the following error:

Can't locate HTML/Entities.pm: Permission denied at ./script.pl line 3.

BEGIN failed--compilation aborted at ./script.pl line 3.

Another is:

Can't locate POSIX.pm: Permission denied at ./script.pl line 3.

BEGIN failed--compilation aborted at ./script.pl line 3.

While trying just to run Perl debug mode (something I've done a lot in order to "test" things using the debug features), I get:

>perl -d

Can't locate perl5db.pl: Permission denied.

BEGIN failed--compilation aborted.

I *really* need to be running Perl soon for a project. But, it looks like Perl is completely messed up from the upgrade to El Capitan, or some upgrade to it that was done since the last time I was running Perl.

Can anyone give me step-by-step instructions on how to fix this, short of re-installing everything from scratch?

Thanks in advance.