$pid_c=fork();                          #create child as working slave
if (defined $pid_c) 
{
    if ($pid_c==0)                                 #child process does the job
    { 
        system("growisofs -Z $device=$isofile >$tmpfile 2>&1");
        exit;
    }
    else                                           #parent job only does output
    {
        for(;;)
        {
            select(undef,undef,undef,0.1);         #sleep for 0.1 sec
            # Fortschritt abprüfen...
            if (kill(0,$pid_c)==0) {
              last;                                #child finished; go on
            }           
        }
    }
} else {
  die ("Cant fork!");
}