use strict;
$|=1;

my $forked = 0;
$SIG{CHLD} = \&REAPER;          # set handler for fork

for (1..10)
{
    my $pid = fork();
    die "Fork failed" unless defined $pid;
    if ($pid == 0)
    {
        print "Hello $$\n";
        sleep 1;
        print "Bye $$\n";
        exit;
    }
    else
    {
        $forked++;
        print "Started child $pid\n";
    }
}

print "Waiting for children to finish..";
while ($forked > 0)
{
    print "[$forked] ";
    sleep 1;
}
print "Done\n";

exit;

sub REAPER
{
    my $pid = wait;
    $SIG{CHLD} = \&REAPER;      # reinstall for sysV (not needed)
    print "Finished child process $pid" . ($? ? " with exit $?" : "") . "\n";
    $forked--;
}