How to detect pending system shutdown on Linux?

Question

I am working on an application where I need to detect a system shutdown. However, I have not found any reliable way get a notification on this event.

I know that o

Answer 1

Its a little bit of a hack but if the server is running systemd if you can run

/bin/systemctl list-jobs shutdown.target

... it will report ...

JOB UNIT            TYPE  STATE
755 shutdown.target start waiting     <---- existence means shutting down

1 jobs listed.

... if the server is shutting down or rebooting ( hint: there's a reboot.target if you want to look specifically for that )

You will get No jobs running. if its not being shutdown.

You have to parse the output which is a bit messy as the systemctl doesnt return a different exit code for the two results. But it does seem reasonably reliable. You will need to watch out for a format change in the messages if you update the system however.