Miscellany

pcntl_signal(SIGTERM, "sig_handler"); 

function sig_handler($signo) { 

    switch($signo) { 
        case SIGTERM: 
            // handle shutdown tasks 
			syslog(LOG_INFO, "CAUGHT SIGTERM. Closing up shop and going home.");
			syslog(LOG_INFO, "Complete");
			closelog();
            exit; 
            break; 
        case SIGHUP: 
            // handle restart tasks 
            break; 
        case SIGUSR1: 
            print "Caught SIGUSR1...\n"; 
            break; 
        default: 
            // handle all other signals 
    } 

} 


***********************************
Creating a daemon with php and fork.
***********************************
<?php 
declare(ticks=1); 

$pid = pcntl_fork(); 
if ($pid == -1) { 
    die("could not fork"); 
} else if ($pid) { 
    exit(); // we are the parent 
} else { 
    // we are the child 
} 

// detatch from the controlling terminal 
if (!posix_setsid()) { 
   die("could not detach from terminal"); 
} 

// setup signal handlers 
pcntl_signal(SIGTERM, "sig_handler"); 
pcntl_signal(SIGHUP, "sig_handler"); 

// loop forever performing tasks 
while(1) { 

   // do something interesting here 

} 

function sig_handler($signo) { 

    switch($signo) { 
        case SIGTERM: 
            // handle shutdown tasks 
            exit; 
            break; 
        case SIGHUP: 
            // handle restart tasks 
            break; 
        default: 
            // handle all other signals 
    } 

} 

?>

*******************************************************************************
* Here's an example of how to get data back from the child. That's the missing
*  piece.
*******************************************************************************


You can use IPC to achieve just that.  Every child that is spawned has to tell its parent that time has come for him to be terminated.  So, yes, zombies will be created, but once in a while the parent will 'clean up' after his kids.  Code:

<?php
  declare(ticks = 1);
  // create a IPC message queue
  $msgqueue = msg_get_queue(ftok("/tmp/php_msgqueue.stat", 'R'),0666 | IPC_CREAT);
  // loop for 1000 children
  for ($c = 0; $c < 1000; $c++) {
   // fork
   $pcid = pcntl_fork();
   if ($pcid == -1) {
     die("Could not fork!");
   }
   elseif ($pcid) { // we are the parent, look for zombie kids and terminate 'em
     // look in the IPC message queue if there are any entries
     $currentqueue = msg_stat_queue($msgqueue);
     $n = $currentqueue['msg_qnum']; // number of messages (number of kids to terminate)
     if ($n > 0) {
       echo "There are $n kids to terminate.\n";
       for ($i = 0; $i < $n; $i++) {
         // pop the kid's PID from the IPC message queue
         if (!msg_receive ($msgqueue, 1, $msg_type, 16384, $msg, true, 0, $msg_error)) {
           echo "MSG_RECV ERROR: $errmsg \n"; // something has gone wrong
         }
         else {
           pcntl_waitpid($msg, $tmpstat, 0); // terminate kid for real.
         };
       };
     };
   }
   else { // we are the child!
     if (!posix_setsid()) { die ("Could not detach"); }; // detach
     echo "I am child number $c\n";
     sleep(5); // do something useful
     // tell dad I'm finished via IPC: send him my PID
     if (!msg_send($msgqueue, 1, posix_getpid(), true, true, $errmsg)) {
       echo "MSG_SEND ERROR: $errmsg \n";
     };
     exit(); // become a zombie until dad kills me                           
   };
  };
?>