I have an iMac (late 2009 model) running Yosemite. Recently, I have set up automatic shutdown in the Energy Saver settings under System Preferences. However, if my computer goes into sleep mode before the automatic shutdown - which I have scheduled to happen after twenty minutes of inactivity - my computer will not shutdown automatically at the scheduled time.
The question: is there a way to make my iMac shutdown at the scheduled time even when it is in sleep mode, or is there no way to circumvent this and I'm better off with manual shutdowns or disabling sleep mode?
By default, events will wake a sleeping Mac before being performed. Typically your Mac will be woken 15 – 30 seconds before the scheduled shut down begins. Ultimately, the wake up is performed by OS X's IOPMQueue which you can see and edit through the pmset tool.
I am the engineer behind Power Manager, so do ask if you need more details.
The Mac will be prevented from auto shutdown if goes to sleep first. It must be fully awake.
Solution: Set the auto wake schedule 5 mins before the auto shutdown.
To shut down automatically, your Mac must be awake at the time that it's scheduled to shut down, and remain awake for at least 10 minutes past that time. If it's sleeping at the scheduled shutdown time, it continues sleeping instead of shutting down. If it's set to go to sleep after less than 15 minutes of inactivity, it might go back to sleep before it can shut down. To make sure that your Mac shuts down even when sleeping, set it to start up or wake 5 minutes before the scheduled shutdown time.