hi,
i have an ubuntu 18.04 server which reboots periodically to apply kernel upgrades.
i'd like to set it up so that a script run just before the machine shuts down.
how can i do that?
thanks!

Possible solution: https://unix.stackexchange.com/quest...efore-shutdown

wow, that looks pretty much complicated!

let me explain my case...

i have a home server where /tmp is mounted as a tmpfs and i use it to save the lastpass-client cache.
it contains very sensitive data, so i think this is a good way to protect it if someone comes in and steals the pc: if that happens, the pc will be shut down and the cache directory in /tmp would be deleted (and, as far as i know, unrecoverable).


this way, however, the cache is lost when the system reboots after an upgrade, as well.
just before those reboots, therefore, i would move the /tmp/lpass_cache directory to $HOME, and then move it again to /tmp just after the reboot.


this is the command i'd like to run before the pc powers off:

and then i would set a cron job like this:

what do you think about?

i read some systemd service files documentation but i still haven't found how to run a command before the shutdown of a REBOOT sequence only...

I don't believe there is a difference in the "shutdown" process between reboot and physical shutdown. The difference is what happens after all the processes have ended. That is, either the 'puter is booted or switched off.

So, what you're proposing would seem to defeat the purpose for which you're using /tmp if you automated it. Your last-pass cache would always get backed up to $HOME and would therefore be available in the event of a theft of the hardware.

Perhaps all you need to do is script the backup and restore processes and run them manually when needed.