The other oddity is not directly related to this problem but involves the system perl on Apple's latest macos: sonoma. My hunt for B.pm revealed that although the system perl is 5.30.3 there is also a full set of core modules for perl 5.34 installed from the factory:

/System/Library/Perl/5.30/darwin-thread-multi-2level/B.pm
/System/Library/Perl/5.34/darwin-thread-multi-2level/B.pm

www.cpan.org/ports/binaries.html#macos

I wonder why perl 5.26.2 on macos 10.13.4 ignores my local copy of B at b.pm but perl 5.38.2 on macos 14.3 tries to use it and gets confused?

I don't think that's actually happening.
On a case-sensitive system (which yours is ?) "use B;" will not load b.pm because of the case mismatch.
UPDATE: Hmmm ... apparently macos systems are typically case-insensitive, so I could be wrong there.

Also, I think that 1.68 is the version that ships with perl-5.26.2, so it's more likely to be loading that B.pm .

In addition to "use lib" directives, also check to see whether the PERL5LIB environment variable is pulling additional paths into @INC.
Maybe it's set for your perl environment, but the apache environment doesn't see it.

Anyway, you're on the right track.

Cheers,
Rob

>> I wonder why perl 5.26.2 on macos 10.13.4 ignores my local copy of B at b.pm

> I don't think that's actually happening.
> On a case-sensitive system (which yours is ?) "use B;" will not load b.pm because of the case mismatch.

You are right that 5.26.2 is not ignoring b.pm on my old system, but believe it or not it IS using b.pm, and since the version matched it worked. On my new box 5.38.2 was also trying to use b.pm so I renamed it and the problem evaporated. I'm not using apache on the new box yet, even though macs come with 2.4.56 included, but morbo is not bothered by b.pm for some reason.

I don't know why but on macOS you can type perldoc data::dumper and it will work, but on Linux you must spell it Data::Dumper. You can also use lowercase module names when using them in one liners for OO modules, but to call functions you must use the proper case:

perl -Mdata::dumper -we'$d=Data::Dumper->new(\@ARGV);print$d->Dump' fo
+o bar
[download]

$VAR1 = 'foo';
$VAR2 = 'bar';

perl -Mdata::dumper -we'print Dumper(\@ARGV)' foo bar
[download]

Undefined subroutine &main::Dumper called at -e line 1.