On Thu, Dec 24, 2020 at 08:16:12AM -0800, Bryan Linton wrote: > On 2020-12-24 10:31:22, Ian Darwin <i...@darwinsys.com> 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.