PHP Programming/Daemonization

A daemon is an application that runs in the background, as opposed to being directly operated by the user. Examples of daemons are Cron and MySQL. Daemonizing a process with PHP is very easy, and requires PHP 4.1 or higher compiled with --enable-pcntl. Building a Daemon We'll start with set_time_limit(0) to let our script run indefinitely. Next, we fork the PHP process with pcntl_fork(). Finally, we use posix_setsid() to tell the child process to run in the background as a session leader. <? set_time_limit(0); // Remove time limit if (pcntl_fork()) { // Fork process print "Daemon running."; } else { $sid = posix_setsid(); // Make child process session leader if ($sid < 0) exit; while (true) { // Daemon script goes here } } ?> The code inside the while statement will run in the background until exit or die is explicitly called. Applications While daemonizing a script can be useful, it is not appropiate for every script. If a script only needs to be executed at a certain time, it can take advantage of Cron for scheduled execution. See also Nanoserv Sonic Server Daemon