Installation of Perl distribution is finished. Please note, that
since Perl is also in the base system, this distribution will not
be used by default.

If you want this version of Perl to be used by default, please type

 use.perl port

Assuming that use.perl script (which was installed with the rest
of the Perl distribution) can be found in your PATH (you might have
to type `rehash' first, depending upon a shell you use), this action
will replace /usr/bin/perl and /usr/bin/suidperl with symbolic links
to the versions of these binaries in the Perl distribution. This
action will also put some variables into your /etc/make.conf file,
so that newly installed ports (not packages!) will use new version
of perl, and the system upgrades from the source will not overwrite
the changes made.

At any time you can also type

 use.perl system

if you wish to revert back to the system version of perl.
              

なのだそうだ。