launchd in Depth

"When Apple decided to overhaul the 30 year old system for starting and maintaining processes on UNIX it had to think big. launchd can do the jobs of init, mach_init, xinetd, RC, SystemStarter, watchdog, and cron. It is Apple's stated intention that they want to eliminate all of those services in favor of launchd at some point in the future."

"When it comes down to it, launchd has two main tasks. The first is to boot the system and the second is to load and maintain services."

"launchd is very different from SystemStarter in that it may not actually launch all the daemons at boot time. [...] This is why Tiger boots so fast. The system only has to register the daemons that are to run, not actually launch them. In fact the progress bar that appears is just a placebo that doesn't really show anything other than the passage of time. This explains why the bar never reaches the end before the login window appears sometimes."

"launchd is here, and it is the future of service management on Mac OS X. Apple has opened the project in the hopes that other *NIX vendors will take a look at it and incorporate it into their own OSes."