Monitoring and Restarting Critical Services

In earloier versions of Mac OS X, a daemon called watchdog monitored critical services and restarted them if they failed or quit unexpectedly after a computer restarted. The watchdog daemon relied on the configuration file watchdog.conf, located in /etc.

In Mac OS X Server version 10.4, watchdog has been replaced by launchd. The launchd daemon manages other daemons, both for the computer as a whole and for individual users. You can configure the launchd daemon to launch other daemons on demand, based on criteria specified in their respective XML property lists.

During system startup, launchd is the first process invoked by the kernel to run and set up the rest of the computer. In Mac OS X Server, it is preferable to have your daemon started by launchd.

Note: Some system administrators need to modify the boot process to insert a script or implement a change in the default system configuration. System administrators are encouraged to work with launchd to implement whatever changes they require, and avoid modifying rc or creating a SystemStarter Startup Item. The rc command script may be phased out in the future.

The configuration files are located in the following folders:

Folder

Usage

/System/Library/LaunchAgents

Configuration for the system

 

 

/System/Library/LaunchDaemons

Configuration for the daemons

 

 

~/Library/LaunchAgents

Configuration per user

 

 

Chapter 4 Restarting or Shutting Down a Computer

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Apple Mac OS X Server manual Monitoring and Restarting Critical Services, Folder Usage