[launchd-dev] Questions on mixed triggers and calendar triggers

[Damien Sorresso]

On Jul 23, 2010, at 9:21 AM, Michael_google gmail_Gersten wrote:
>>> For instance, is it possible to launch a daemon both on schedule with StartCalendarInterval and a mach message? The idea being the process would be run at a specific time of the day but could also be launched "manually".
>> 
>> Yes. Though why would you want your daemon to run on a timer interval if you can just launch it on-demand whenever you need to?
> 
> Maybe you want it to run once an hour anyways.

Why? I'm of the opinion that in most cases, when people use a timer, they're using it as a substitute for tracking some state which they cannot track.

> Maybe you also want it to run when a disk is attached.
> 
> Maybe you even want it to run when you wake from sleep.

Neither of those is possible currently. So yeah, I guess you could run it every hour to make up for it... but why every hour?

> ** Is there any way for a user program to run on disk attach and/or
> wake from sleep, or is that feature for Time Machine hardcoded? The
> only way I can get my scripts to run at wakeup or attach is by
> hijacking Time Machine's. (run my script instead of backup-helper; my
> script calls backup-helper)


TimeMachine uses SPI.
-- 
Damien Sorresso
BSD Engineering
Apple Inc.