Log File Location and PID File Location Settings for the PHP System_Daemon PEAR Class

If you’re reading this blog post, then chances are, you’ve discovered the wonderful PEAR package called System_Daemon. This well-done package offers the ability to turn any PHP script into a daemon and does a good job of making sure there aren’t memory leaks or problems along the way.

There’s a great demo of the package and an explanation of how to get it up and running on the blog of the creator, Kevin von Zonneveld.

The source code for the demo in the post seems complete enough, but it was missing one major component that seems like it would be common for users. The post unfortunately leaves out how one can set the location of the log file or the PID file for the daemon to run. This is a common necessity for many “shared system”-esque environments that exist out there or for those who just happen to be working under restricted permissions. The documentation for the class doesn’t present this information in an easy-to-find manner either.

So, I’m here to let you know that it’s easy as pie… as long as you know the name of the option you’re looking for. By default, the system seemed to want to use the following for the defaults:

/var/run/{appName}/{appName}.pid

and

/var/log/{appName}.log

There’s a couple steps that you’ll want to take so you can get a System_Daemon up and running under the proper user, using files in locations that are accessible by your user.

First, you’ll want to grab the UID and GID of the user you’d like your daemon to run as. This can be achieved by the following command:

id

Once you’ve got your UID and GID, you can get to setting the options for your System_Daemon.

<?php
// Setup
$options = array(
    'appName' => ... 
    ...
    ...
    'appRunAsGID' => your UID,
    'appRunAsUID' => your GID,
    // This sets where you want the log file to be located
    'logLocation' => '/home/uesrname/daemon.log',
    /**
       * This sets where you want the pid file to be created. 
       * Be careful, there's an undocumented restriction on 
       * the naming convention for where the pid file can be 
       * written. It must be in a directory by the same name 
       * as the pid file like the example below. I don't know 
       * why, but it will throw an error if you try to set it 
       * otherwise.
       */
    'appPidLocation' => '/home/username/daemon/daemon.pid'
);
?>

There you have it. By setting the logLocation and appPidLocation options, you can tell the daemon where you’d like the log files to write to and where the pid should be created. Then, by setting your appRunAsGID and appRunAsUID properly, you’ll be up and running scripts as daemons in no time. While the GID and UID settings may have been evident in the aforementioned demo from the author, the logLocation and appPidLocation options may not have been so clear.

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