$ /usr/bin/perl -v

This is perl 5, version 12, subversion 3 (v5.12.3) built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)
...

##</code><code>##

$ /usr/bin/env perl -v

This is perl 5, version 14, subversion 2 (v5.14.2) built for darwin-thread-multi-2level
...

##</code><code>##

$ /opt/local/bin/perl -v

This is perl 5, version 12, subversion 3 (v5.12.3) built for darwin-multi-2level
...

##</code><code>##

$ pm_readline_perl_mac.pl
Enter: 
> 1+2
$ pm_readline_perl_mac.pl
Enter: 
> blah blah
$ 

##</code><code>##

$ echo $PERL_RL

$