*Good for yosemite or snow leopard
-
Edit the /System/Library/LaunchDaemons/com.apple.atrun.plist, change the disabled child node from true -> false.
-
Unload the current /System/Library/LaunchDaemons/com.apple.atrun.plist with:
sudo launchctl unload -F /System/Library/LaunchDaemons/com.apple.atrun.plist
Then load the edited version