#!/usr/bin/perl

use strict;
use warnings;

my $pid=fork();
defined($pid) or die "Can't fork: $!";
if ($pid) {
    # parent
    print "Parent waiting for the child ...\n";
    waitpid($pid,0);
    print "Child has exited, exit code = $?\n";
} else {
    # child
    chdir('/tmp') or die "Can't chdir to /tmp: $!";
    %ENV=(); # completely clear environment, for shorter demo output, maybe also for security
    $ENV{'PATH'}='/bin:/usr/bin';
    $ENV{'FOO'}='foo fofoo fofofooo';
    $ENV{'BAR'}='bar bar barrrrrrrrrk';
    exec($^X,'-e','print "* Hello from a new perl\n";print `pwd`;print "* $_=$ENV{$_}\n" for sort keys %ENV; print "* bye\n"')
        or die "Can't execute $^X: $!";
    # not reached
}

##</code><code>##

>perl envchild.pl
Parent waiting for the child ...
* Hello from a new perl
/tmp
* BAR=bar bar barrrrrrrrrk
* FOO=foo fofoo fofofooo
* PATH=/bin:/usr/bin
* bye
Child has exited, exit code = 0
>