That's a FAQ, both a Unix FAQ and a Perl one (see perlfaq8).

See also:

• export environment variable from a perl program
• How do I set env. Variables from Perl with shell script
• Get default login environment
• Source command in perl script
• Shell::EnvImporter

That's not how the environment works. Changes are only visible to the current process and its children. You cannot change the "upwards" environment.

The traditional technique is to output a shell script that the "upper" process then evaluates:

# In the parent shell do:
$(perl -wle 'print "export pathy=kuku')
echo $pathy
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#!/usr/bin/perl

use strict;
use warnings;

setter( $ENV{'pathy'} = 'kuku' );
system("env");

sub setter {
    shift;
    while ( my ( $key, $value ) = splice @_, 0, 2 ) {
        $ENV{$key} = $value;
        }
        return;
}
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