UPSSCHED(8) Network UPS Tools (NUT) UPSSCHED(8)
upssched - Timer helper for scheduling events from upsmon
upssched should be run from upsmon(8) via the NOTIFYCMD. You should never run it directly
during normal operations.
upssched was created to allow users to execute programs at times relative to events being
monitored by upsmon(8). The original purpose was to allow for a shutdown to occur after
some fixed period on battery, but there are other uses that are possible.
upssched needs to be called as the NOTIFYCMD in your upsmon.conf(5). It determines what
is happening based on the UPSNAME and NOTIFYTYPE environment variables. You should never
have to deal with them directly.
Set the EXEC flag on the events that you want to see in upssched. For example, to make
sure that upssched hears about ONLINE, ONBATT and LOWBATT events, the flags would look
NOTIFYFLAG ONLINE EXEC
NOTIFYFLAG ONBATT EXEC
NOTIFYFLAG LOWBATT EXEC
If you also want to continue writing to the syslog, just add it in:
NOTIFYFLAG ONLINE SYSLOG+EXEC
NOTIFYFLAG ONBATT SYSLOG+EXEC
NOTIFYFLAG LOWBATT SYSLOG+EXEC
For a full list of notify flags, see the upsmon(8) documentation.
See upssched.conf(5) for information on configuring this program.
To shut down the system early, define a timer that starts due to an ONBATT condition.
When it triggers, make your CMDSCRIPT call your shutdown routine. It should finish by
calling "upsmon -c fsd" so that upsmon gets to shut down the slaves in a controlled man-
Be sure you cancel the timer if power returns (ONLINE).
If your UPS goes on and off battery frequently, you can use this program to reduce the
number of pager messages that are sent out. Rather than sending pages directly from
upsmon(8), use a short timer here. If the timer triggers with the UPS still on battery,
then send the page. If the power returns before then, the timer can be cancelled and no
page is necessary.
This program was written primarily to fulfill the requests of users for the early shutdown
scenario. The "outboard" design of the program (relative to upsmon) was intended to
reduce the load on the average system. Most people don't have the requirement of shutting
down after n seconds on battery, since the usual OB+LB testing is sufficient.
This program was created separately so those people don't have to spend CPU time and RAM
on something that will never be used in their environments.
The design of the timer handler is also geared towards minimizing impact. It will come
and go from the process list as necessary. When a new timer is started, a process will be
forked to actually watch the clock and eventually start the CMDSCRIPT. When a timer trig-
gers, it is removed from the queue. Cancelling a timer will also remove it from the
queue. When no timers are present in the queue, the background process exits.
This means that you will only see upssched running when one of two things is happening:
- There's a timer of some sort currently running
- upsmon just called it, and you managed to catch the brief instance
The final optimization handles the possibility of trying to cancel a timer when there are
none running. If the timer daemon isn't running, there are no timers to cancel, and fur-
thermore there is no need to start a clock-watcher. So, it skips that step and exits
The NUT (Network UPS Tools) home page: http://www.exploits.org/nut/
NUT mailing list archives and information: http://lists.exploits.org/
Wed Feb 6 2002 UPSSCHED(8)