#/bin/sh
# ...
export PERL5LIB=`perl -e '
    use strict; use warnings;
    my @addinc = ("/usr/local/lib/perl5/site_perl",
                  "/Users/me/perl/perl_lib"
                 );
    my %inc = map { $_, 1 } split (/\:/, $ENV{PERL5LIB});

    for (@addinc) { # this was just updated
        $inc{$_} or print "$_:";
    }
    print "$ENV{PERL5LIB}\n";
'`