How do I automatically boot ubuntu?

[StefBen]

I have already figured out how to shut down my Raspberry Pi with ubuntu mate, but I haven't found a way to automatically start it at a given time. (Maybe I could keep part of the system awake, but I would prefer to limit the processes as much as I can since I'm not using it)

[dgsddfgdfhgs]

theres no power switch functions, just use physical timer on wall plugs

[FloRolf]

I'm not sure about the RPi but most normal motherboards have a power on function in the bios where you can set a specific time. 

 

But the Pi just immediately powers on when it receives power from the outlet doesn't it? So a physical timer might be the best option. 

[Koeshi]

3 hours ago, FloRolf said:

But the Pi just immediately powers on when it receives power from the outlet doesn't it?

That is correct.  The Pi doesn't even really have a BIOS (at least in the way that people normally understand it) and so things like sleep modes and waking at set times are not possible without add-ons.  As I remember there was a HAT that added RTC so that you could do timed waking on it, but that was a long time ago so I may be remembering wrong.

[captain_aggravated]

One barrier to doing this with a Raspberry Pi, as Koeshi mentioned, is the lack of a hardware real-time clock.  The Pi doesn't have one, it checks with the internet when it first boots (if it can) or lets the user set the clock, and then keeps up with it from there.  When shut down, that stops functioning.  Also, as far as I know, once the Pi has received the shut down signal, it is basically inert until power is removed and applied again.

 

Would suspending the machine until a given time do the task you're looking for?

[StefBen]

10 hours ago, captain_aggravated said:

One barrier to doing this with a Raspberry Pi, as Koeshi mentioned, is the lack of a hardware real-time clock.  The Pi doesn't have one, it checks with the internet when it first boots (if it can) or lets the user set the clock, and then keeps up with it from there.  When shut down, that stops functioning.  Also, as far as I know, once the Pi has received the shut down signal, it is basically inert until power is removed and applied again.

 

Would suspending the machine until a given time do the task you're looking for?

If it's the only way without buying something external yes. is the suspend mode consuming a lot in terms of hardware life? I'm running it 24/7 and from midnight to 1pm I don't use it so I'm trying to save as much hardware life as I can since it doesn't even have a fan 

[Koeshi]

8 hours ago, StefBen said:

I'm running it 24/7 and from midnight to 1pm I don't use it so I'm trying to save as much hardware life as I can since it doesn't even have a fan 

You will find a lot of people that leaves Pis running for 24/7 for years at a time without issue.  Also, unless you are really stressing out the CPU in a confined environment you don't need to worry about a fan.  Just stick a decent sized heatsink on it and passive cooling should be enough.

[QXC]

Also, if you've got a Pi3 + (A+ or B+), the heatspreader does a surprisingly good job of helping keep the chip cool compared to older models. Airflow is still always good, but even if it gets too hot it'll just turn the clocks down a bit.

 

EDIT:

 

But going back to the original question, if you have a Pi3 B+ and also have the PoE hat for it, you can try to automate PoE on that particular port of the switch as a way of turning the Pi on without physical intervention. Since you are shutting down the Pi via software right now, you'd probably want to just "flick" the PoE off and on to start it up. Once the Pi is getting power, Ubuntu will boot itself as per normal.

 

Like others have said, due to the hardware limitations of the Pi (a search for "Pi Wake On Lan" brings up similar discussions), the only real way to get it to boot on it's own is to power cycle the device. PoE is one of the more convenient ways to do that.