Power down facility, to power down the local system if another/remote host goes offline.
This utility is useful in cases, like mine, you have a local (LAN) unmanaged Linux server which you start (manually or, like me, by using Wake On LAN) when a client system goes up and then, when the same client system shuts down, you want your server to automatically follow (in a few).
There is a "double check", before the server really shuts down: this is made to avoid having "early shutdowns" in case of (1) temporary LAN disconnection of the server and/or the "reference" client, (2) to suit the need, sometimes, to keep the server up, when just starting alone or after a client's shutdown: in such cases you should have the time to access server's console and stop the automation by issuing a command.
(excerpt from manpage)
This system utility will do a check every 5 minutes (accordingly to configuration's default, if unchanged) and, if the remote reference host is found inactive, even the local host will be shut down. Options/commands are provided to temporarily or completely stop the automated checks and to see the automation's status, plus a couple of shutdown's related utilities. Read the full documentation for further and technical details.
OPTIONS
no option Via Cron automated checks (see /etc/cron.d/pwrdown): after the second check, if the remote system doesn't answer, the local one is shut down. Via command line: checks are forced, same behavior as via Cron but without the usual delays (good for testing).
-a, --auto Automatic processing restored, cleaning the global semaphore PWRDOWN_NO (see --noauto).
-f, --pwrdown Forces an immediate shutdown/poweroff, same as "shutdown -h now".
-r, --reboot Forces an immediate reboot, same as "shutdown -r now".
-s, --noauto Stops the automatic processing, setting the global semaphore PWRDOWN_NO which remains through sessions.
-S, --status Shows the current automation's status: short and global semaphores, and remote host status.
-p, --postpone If the first shutdown warning was received, the further shutdown action can be postponed for 5 mins (default) without completely stopping the automation.
-n, --dry-run Do the same as no option is given (automated process), but without really shutting the system down.
--playtest1 play the system-alive sounds only (test purposes)
--playtest2 play the warning sounds only (test purposes)
--playtest3 play the shutdown sounds only (test purposes)
-h, --help Display a short help and exits.
-V, --version Display program's version, build, author, license and exits.
IMPORTANT NOTES to Git downloaders
The whole package is made to be contained into its own directory (my default: /usr/local/share/pwrdown/) but, as usual into a Linux system, you'll need to "spread" parts throughout your system, or it won't work: my solution, to keep the package in its own directory tree (to keep its management easy), was to use symlinks, instead of creating some kind of "installation": to know where the symlinks have to be placed, just look at the very first line of each file (they're all source, no object files here): every path and (symlink) name is written there.