Oh yes, you're entirely right. I tested with

[SiDMBP2:~] urinine% perl dog.pl
Can't locate feature.pm:   Permission denied at dog.pl line 1.
BEGIN failed--compilation aborted at dog.pl line 1.
[SiDMBP2:~] urinine% sudo perl dog.pl
Hello World
Wednesday
[download]

So it IS permissions. Okay what's the issue:

[SiDMBP2:~] urinine% perl -e 'print(join("\n", @INC))' | xargs ls -ld
ls: /Library/Perl/Updates/5.18.4: Permission denied
ls: /Network/Library/Perl/5.18: No such file or directory
ls: /Network/Library/Perl/5.18/darwin-thread-multi-2level: No such fil
+e or directory
drwxr-xr-x+  55 urinine  staff  1760 Oct 14 14:32 .
drwxr-xr-x   25 root     wheel   800 Oct 14 11:08 /Library/Perl/5.18
drwxr-xr-x   11 root     wheel   352 Oct 14 11:08 /Library/Perl/5.18/d
+arwin-thread-multi-2level
drwxr-xr-x  130 root     wheel  4160 Jul 24 08:26 /System/Library/Perl
+/5.18
drwxr-xr-x   56 root     wheel  1792 Jul 24 08:26 /System/Library/Perl
+/5.18/darwin-thread-multi-2level
drwxr-xr-x  109 root     wheel  3488 Aug 17  2018 /System/Library/Perl
+/Extras/5.18
drwxr-xr-x   72 root     wheel  2304 Sep 21  2018 /System/Library/Perl
+/Extras/5.18/darwin-thread-multi-2level
[download]

So what's in that first directory

[SiDMBP2:/Library/Perl] urinine% sudo ls -l /Library/Perl/Updates/5.18
+.4
total 0
drwx------  3 root  wheel  96 Oct 14 11:03 darwin-thread-multi-2level

[SiDMBP2:/Library/Perl] urinine% sudo ls -l /Library/Perl/Updates/5.18
+.4/darwin-thread-multi-2level
total 16
-rw-------  1 root  wheel  7027 Oct 14 11:08 perllocal.pod
[download]

Yep. Can't access those. So can I pull that out of my @INC somehow, or should I just blast some ugly overblown permissions over the directories?

Well I'm not familiar with macs, but assuming all those paths are hard-coded into your perl binary (you can check with perl -V) then it seems most likely that the permissions on the directory is the thing needing fixing.

Dave.

Those directories hold the installed Perl system and should be 0755 for directories and 0644 for files. I believe that chown a+rX -R `perl -e 'print(join("\n", @INC))'` at a root prompt should fix it. The root cause was probably a bad umask value while updating Perl modules.

Those permissions are not overblown at all — most of the system should be accessible to all users.