function: pcntl_signal()

problem: If "handler" argument is set to a user-defined 
function, that function is never called.

script: (taken from www.php.net/pcntl_signal)
<?php

// signal handler function
function sig_handler($signo) {
	echo "We hit the sig_handler!\n";
     switch($signo) {
         case SIGTERM:
             // handle shutdown tasks
             exit;
             break;
         case SIGHUP:
             // handle restart tasks
             break;
         case 1:
         	print "Caught sig 1 ...\n";
         	break;
         case SIGUSR1:
             print "Caught SIGUSR1...\n";
             break;
         default:
             // handle all other signals
     }

}

print "Installing signal handler...\n";

// setup signal handlers
pcntl_signal(SIGTERM, "sig_handler");
pcntl_signal(SIGHUP, "sig_handler");
pcntl_signal(SIGUSR1, "sig_handler");

print "Generating signal SIGTERM to self...\n";

// send SIGUSR1 to current process id
posix_kill(posix_getpid(), SIGUSR1);

print "Done\n"

?>

The "we hit the sig handler!" echo never appears ... thus I 
suspect it's never being called.