In Mac OS X you can use cron to schedule tasks but you can also use launchd. To use launchd to load or unload an agent where you’ve setup a task use the launchctl command. Here we will use launchctl to manually start a process given that we defined a plist called /Library/LaunchAgents/com.apple.OpenProgram.plist (where program is maybe the name of some program you want to fire up):
launchctl load Library/LaunchAgents/com.apple.OpenProgram.plist
Your application should fire up now. Do not quit it for ten seconds. Wait about 15, then quit it. Notice it start up again. This is because it is a launchAgent and will restart any time it is closed. Now run:
launchctl unload Library/LaunchAgents/com.apple.OpenProgram.plist
Watch your program close.