Lingon linked on Astoundingly useful programming tools

Mac OS X contains a powerful alternative to cron, called launchd. Unlike cron, launchd can run scripts not just based on time of day but on repeated intervals; it can also ensure that scheduled scripts run when the computer starts up if the computer is turned off when their scheduled time comes around.

Launchd can also run applications that need assistive access, making it possible to schedule such apps without using an AppleScript app running all the time in the background.

Launchd is also, however, a lot more complicated to set up than cron jobs. I still use cron for most scheduling because cron is easier to maintain. Lingon, however, goes a long way toward making launchd almost as easy to use as cron. This is the only case in the book where I do things differently than I describe: I use Lingon to tell launchd to run an Automator app that runs the schemail e-mail scheduler.

I didn’t want to require you to buy third-party software. But I do recommend it if you use schemail but don’t like having an AppleScript app running all the time.