In a new post to his blog Kevin van Zonneveld talks about making daemons, backend scripts that run independent of a web server.
Everyone knows PHP can be used to create websites. But it can also be used to create desktop applications and commandline tools. And now with a class called System_Daemon, you can even create daemons using nothing but PHP. And did I mention it was easy?
He starts with a definition ("a linux program that runs in the background") and why PHP makes a good language choice for creating them. His example uses the System_Daemon PEAR class to do most of the heavy lifting. To use it, you only need to include it at the top of the script and make two calls to the setOption and start methods to have the rest of the code all set to run as a daemon.
The example code sets up a daemon complete with support for command-line arguments and the ability to be run from init.d on the local system.