#!/usr/bin/perl

  use warnings;
  use strict;

  $SIG{CHLD} = 'IGNORE';  # to make sure there are no zombies

  sub run_shell(@) {
      my $pid = open my $pipe, "-|";
      die "can't open forked pipe': $!" unless defined $pid;
      if ($pid) {
          # parent
          return { pid => $pid, pipe => $pipe };
      }
      # child
      open STDERR, ">&STDOUT" or die "can't dup 2>&1: $!";
      setpgrp;  # move into its own process group
      exec @_;  # give control of child to command
      die "exec @_ failed: $!";  # should never get here
  }

  my $subshell = run_shell qw(./forkage.sh);
  my $output_from_subshell = $subshell->{pipe};
  my $lines_left = 20;
  print while defined($_ = <$output_from_subshell>) and $lines_left--;
  kill "HUP", -$subshell->{pid};