#!/usr/bin/env perl

use 5.008;

use strict;
use warnings;

$ENV{test} = 'TURE';

exec $ENV{SHELL}
    or die "Failed to exec shell '$ENV{SHELL}'\n";

##</code><code>##

$ echo "PID=$$; test='$test'"
PID=87533; test=''
$ exec ./exec.pl 
$ echo "PID=$$; test='$test'"
PID=87533; test='TURE'