>>> Lennart Poettering <lenn...@poettering.net> schrieb am 16.02.2022 um 18:17 in Nachricht <Yg0xkENt8XNvo+y4@gardel-login>: > On Mi, 16.02.22 14:09, Ulrich Windl (ulrich.wi...@rz.uni‑regensburg.de) wrote: > >> Hi! >> >> I wonder: Is it possible with systemd to detect multiple reboots >> within a specific time interval, and react, like executing some >> systemctl command (that is expected to "improve" things)? With >> "reboots" I'm mainly thinking of unexpected boots, not so much the >> "shutdown ‑r" commands, but things like external resets, kernel >> panics, watchdog timeouts, etc. > > The information why a system was reset is hard to get. Some watchdog > hw will tell you if it was recently triggered, and some expensive hw > might log serious errors to the acpi pstore stuff, but it's all icky > and lacks integration.
Lennart, you got me wrong: I don't want to filter on the reasons of the (re)boot, but I just wanted to rule out any possible solution that stores information during an orderly shutdown/reboot ;-) > > A safe approach would probably to instead track boots where the root > fs or so is in dirty state. Pretty much all of today's file systems > track that. In the past (when there are a few logins only) I would have been tempted to use "last" to grep for boots, but if there are many (automated) logins, those boots may be "rolled out" and thus won't be counted possibly. > > It sounds like an OK feature to add to the systemd root fs mount logic > to check for the dirty flag before doing that and then using that is > hint to boot into a target other than default.target that could then > apply further policy (and maybe then go on to enter default.target). > > TLDR: nope, this does not exist yet, but parts of it sound like > worthwile feature additions to systemd. Something very primitive: a) Increment some counter on every boot, and reset that counter after some time. b) Check the counter and if it is >= some threshold, execute a one-shot command Could systemd help with a) and b)? Regards, Ulrich > > Lennart > > ‑‑ > Lennart Poettering, Berlin
