{
	local $SIG{HUP} = 'IGNORE';
	kill HUP => -$$;
}

##</code><code>##

#!/opt/perl/bin/perl
use 5.012;
use warnings;

say "A start";

my $pid;

unless ( $pid = fork ) {
	die "cannot fork: $!" unless defined $pid;
	system("./b.pl");
	sleep 30;
	exit;
}

sleep 2;

say "A sending kill HUP -$$";

{
	local $SIG{HUP} = 'IGNORE';
	kill HUP => -$$;
}

say "A waiting for lost children";

while (1) {
	my $kid = waitpid -1, 0;
	$kid == -1 and last;
	say "A reaped child $kid";
}

say "A end";

##</code><code>##

#!/opt/perl/bin/perl
use 5.012;
use warnings;

say "  B start";

my $pid;
unless ($pid = fork) {
	die "cannot fork: $!" unless defined $pid;
	system("./c.pl");
	sleep 30;
	exit;
}

say "  B waiting on lost children";

while (1) {
	my $kid = waitpid -1, 0;
	$kid == -1 and last;
	say "  B reaped child $kid";
}

sleep 30;

say "  B end";

##</code><code>##

#!/opt/perl/bin/perl
use 5.012;
use warnings;

say "    C start";
sleep 30;
say "    C exit";

##</code><code>##

$ ./a.pl
A start
  B start
  B waiting on lost children
    C start
A sending kill HUP -20682
A waiting for lost children
A reaped child 20683
A end