#!/usr/bin/perl

use warnings;
use strict;

my $pid = open(F,"-|");
if (!defined($pid)) { die "fork error: $!\n"; }
if ($pid)
{
  # Parent
  print "PARENT: PID is $$\n";
  sleep(1000);
  print <F>;
  close(F);
}
else
{
  # Child
  exec("/bin/bash","-c", 'echo CHILD: PID is $$, PPID is $PPID >&2');
}