#!/usr/bin/perl 
 use strict;
 use warnings;
 
my $parent_pid = $$;
my $child_pid = 0;
my @child_output;

my $read_from_child = 0;
my $max_timeout = 60;
my $timeout;
	
print "Parent is $parent_pid\n";

my $pid = open(KID_TO_READ, "-|");
defined($pid) || die "can't fork: $!";
#local $SIG{CHLD};
if ($pid) {             # parent
	local $SIG{'CHLD'} = sub { print "dead child\n"; $timeout=0 };
	local $SIG{'USR1'} = sub { ++$read_from_child };
	print "reading kid...\n";
	$timeout = $max_timeout;
	while($timeout >0){
		print "parent $parent_pid timeout=$timeout read_from_child=$read_from_child - child_pid=$child_pid\n";
		if($read_from_child>0){
			--$read_from_child;
			$_=<KID_TO_READ>;
			print "parent $$ just read: $_";
			unless( $child_pid>0 ){
				chomp($child_pid = $_);
			}else{
				push @child_output, $_;
			}			
		}else{
			sleep 1;
			--$timeout;
		}
	}
	close(KID_TO_READ);
} else {                # child
	print $$ . "\n";	# send child pid
	kill('USR1', $parent_pid); # warn parent there is data
	print STDERR "child $$ is running\n";  # print to screen (DEBUG)
	my $program = "/bin/sleep";
	my @args = qw(3);
	my $ret = system($program, @args);
	print "returncode is $ret\n"; # is $?
	print STDERR "returncode is $ret\n"; # print to screen (DEBUG)
	kill('USR1', $parent_pid); # warn parent there is data
	exit 0;
}

print "\nChild $child_pid is done, we now have:\n@child_output\n";


##</code><code>##

Parent is 5323
reading kid...
parent 5323 timeout=60 read_from_child=0 - child_pid=0
child 5324 is running
parent 5323 timeout=59 read_from_child=1 - child_pid=0
parent 5323 just read: 5324
parent 5323 timeout=59 read_from_child=0 - child_pid=5324
parent 5323 timeout=58 read_from_child=0 - child_pid=5324
parent 5323 timeout=57 read_from_child=0 - child_pid=5324
parent 5323 timeout=56 read_from_child=0 - child_pid=5324
returncode is 0
parent 5323 timeout=55 read_from_child=1 - child_pid=5324
parent 5323 just read: returncode is 0
parent 5323 timeout=55 read_from_child=0 - child_pid=5324
dead child

Child 5324 is done, we now have:
returncode is 0