php pcntl_fork

gistfile1.php

<?php  
$pid = pcntl_fork();
if ($pid == -1) {
	die('could not fork');
} else if ($pid) {
	pcntl_waitpid($pid, $status, WUNTRACED); //Protect against Zombie children
	if (pcntl_wifexited($status)) {
		echo "Child exited normally";
	} else if (pcntl_wifstopped($status)) {
		echo "Signal: ", pcntl_wstopsig($status), " caused this child to stop.";
	} else if (pcntl_wifsignaled($status)) {
		echo "Signal: ",pcntl_wtermsig($status)," caused this child to exit with return code: ", pcntl_wexitstatus($status);
	}
} else {
	$test = "tail -n 1 -f /var/www/access.log";  
	$fp = popen($test, "r");
	while (!feof($fp)) {
		$out = fgets($fp, 4096);
	}
	pclose($fp);
}