Since I install pending updates for my Ubuntu server as soon as possible, I have to restart my linux server quite often. I'm running an webapp on that server and would like to warn my users about the pending restart. Right now, I do this manually, adding an announcement before the restart, give them some time to finish their work, restart and remove the announcement.
I hope, shutdown -r +60 writes an file with all the information about the restart, which I can check on every access. Is there such a file? Would prefer a file in a virtual file system like /proc for performance reasons...
I'm running Ubuntu 10.04.2 LTS
If you are using systemd, the following command shows the scheduled shutdown info.
cat /run/systemd/shutdown/scheduled
Example of output:
USEC=1636410600000000
WARN_WALL=1
MODE=reboot
As remarked in a comment by @Björn, USEC is the timestamp in micro seconds.
You can convert it to a human friendly format dropping the last 6 figures and using date like this:
$ date -d @1636410600
Mon Nov 8 23:30:00 CET 2021