Cancel / block a task triggered with delay by windows "task scheduler"
This is related to a specific issue, but I think it is an "interesting" question for general use: In Windows (specifically 2k8 server, for me) you have a task that is triggered by an event (specifically, the UPS goes on battery because power failed) with a delay (the battery will last at least 15 minutes) and then perform some action (specifically, shutdown /s /t 60 /d U:6:12). But there is some other event (specifically, the UPS goes OFF battery because power has been restored) that should then block the first task from happening (specifically, don't shut down) IF it happens during the delay.
I started thinking about this because the software for managing server shutdown that came with my UPS is pure... oh, I'm supposed to be polite here aren't I? ... um... very very not good. So I was thinking about how to provide the standard shutdown before battery runs out functionality without it. Normally, the system would get a message from the UPS that the battery was about to run out, then shut down. This UPS does NOT send that message. It sends "I'm on Battery", "I'm on AC" and that. is. it. No message for "I'm about to die".
But I think that could be a useful trick for other situations as well. Anytime there is something that you want to do after something has been happening for a while without recovery. E.g. if you can't communicate with a remote PC for some period of time, send a message to the smart power strip to power cycle it... But not if the communication is restored. Or if you haven't been able to get data from one source for some period of time, switch to a backup data source... But not if the primary source starts responding.
Can it be done? I don't see a way...
Extending on Ryan's approach using 2 tasks, one triggered by "Power Gone", and an "abort" button task, triggered by a "Power Restore" event
In case you need to do something more generic (not every executable has an abort switch like shutdown), and want to maintain a few-minute buffer before you start sending emails to management, wiping disks or self-destruct the datacenter (or whatever else you want to automate in an emergency), you could make the first one stall/wait for a while, and have the second task stop the first one if triggered:
PowerGone task:
Send-MailMessage -To "[email protected]" -Body "Self-destruction sequence initiated, T-10m"
# We can still abort this task
Start-Sleep -Seconds 600
Send-MailMessage -To "[email protected]" -Subject "Notice of termination..."
Start-Implosion -Force
PowerBack task:
$TaskScheduler = New-Object -ComObject Schedule.Service
$TaskScheduler.Connect("localhost")
$TargetTask = $TaskScheduler.GetFolder('\').GetTask('PowerGone')
$TargetTask.Stop()
This is a neat idea. I would write this for you in Powershell or C#, in a few hours, for a very modest fee. ;)
Just kidding. How about this...
Use Task Scheduler to create two tasks. Each task will be triggered on an Event Log event. Task number one will trigger based on the "AC power is gone" event, and it would execute an action like shutdown /s /t 1200 to shutdown the system with a delay of 1200 seconds. Then the second task will trigger based on the event log event for "AC power has been restored." The second task will execute a shutdown /a to abort the pending shutdown.
I think anything more advanced than that will need to be scripted.
