On Thu, Dec 24, 2020 at 08:16:12AM -0800, Bryan Linton wrote:
> On 2020-12-24 10:31:22, Ian Darwin <[email protected]> wrote:
> > On Thu, Dec 24, 2020 at 11:51:26AM +0100, Gabriel Hondet wrote:
> > > Hi,
> > >
> > > How can I program my computer to automatically wake from suspend to ram
> > > or suspend to disk at a certain time?
> > >
> > > My goal is to suspend a server every day from, say, 11 pm to 7am.
> >
> > For suspending at night, use see the cron man page.
> >
> > For waking up in the morning, of course, the OS isn't running so there is
> > nothing
> > it can do.
In fact I was hoping that it can, since for instance it can be woken up
by pressing a key (although I don't know anything about the mechanics
involved). For this I thought the line
acpi0: wakeup devices LID_(S4) SLPB(S3) IGBE(S4) EXP2(S4) XHCI(S3)
EHC1(S3)
of dmesg could help. It seems, if I'm not mistaken, that Linux supports
such a thing using rtcwake.
> > Some but not all PC BIOSes have a scheduling feature.
Ah that's interesting thank you.
> > Otherwise a
> > $10 mechanical timer to cut the power (well after the suspend is finished!)
> > and
> > turn it back on in the morning.
> >
>
> If shutting down the server entirely (instead of suspending it)
> were an option, you could schedule a cron job to shut it down at a
> given time and send a WoL (Wake on LAN) packet from another
> computer on the network to wake it up again.
>
> Oh, I just skimmed the ifconfig manpage and found the following:
>
> wol Enable Wake on LAN (WoL). When enabled, reception of a
> WoL frame will cause the network card to power up the
> system from standby or suspend mode. WoL frames are sent
> using arp(8).
>
> So it looks like you could even do this while the system were
> suspended if your network card supports it. Of course, this
> depends on having another server on the same, physical LAN as the
> server in question, so the mechanical switch suggestion above might be
> the only option if that's not the case.
That's a good idea as well, thank you.
