use POSIX;
... code here ...
$child_pid = waitpid(-1, WNOHANG);


##</code><code>##

use POSIX;
if ($pid = fork)
{
   # parent
   do
   {
      local $| = 1;
      print "\b-";  sleep 1;
      print "\b\\"; sleep 1;
      print "\b|";  sleep 1;
      print "\b/";  sleep 1;
      $child_pid = waitpid(-1,WNOHANG);
   }  until $child_pid == -1;
}
else
{
   # child
   #exec("cmd");
   sleep 15;
   exit(0);
}

##</code><code>##

use POSIX;
$keep_going = 1;

#set the SIGCHLD signal handler
$SIG{CHLD} = \&REAPER;
if ($pid = fork)
{
   # parent
   while($keep_going)
   {
      local $| = 1;
      print "\b-";  sleep 1;
      print "\b\\"; sleep 1;
      print "\b|";  sleep 1;
      print "\b/";  sleep 1;
   } 
}
else
{
   # child
   sleep 15;
   exit(0);
}

#SIGCHLD signal handler
sub REAPER
{
    #test if all childred are dead
    unless(waitpid(-1, WNOHANG) == -1 )
    {
        $keep_going = 0;
    }
    #reset the signal handler for more than 
    #one child death.
    $SIG{CHLD} = \&REAPER
}