Ubuntu Manpage: upssched - Timer helper for scheduling events from upsmon

Provided by: nut-client_2.7.1-1ubuntu1.2_amd64

NAME

       upssched - Timer helper for scheduling events from upsmon

SYNOPSIS

       upssched

           Note
           upssched should be run from upsmon(8) via the NOTIFYCMD. You should never run it
           directly during normal operations.

DESCRIPTION

       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.

INTEGRATION

       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
       like this:

           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.

CONFIGURATION

       See upssched.conf(5) for information on configuring this program.

EARLY SHUTDOWNS

       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 manner.

       Be sure you cancel the timer if power returns (ONLINE).

DEBOUNCING EVENTS

       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.

BACKGROUND

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
triggers, 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
furthermore there is no need to start a clock-watcher. So, it skips that step and exits
sooner.

FILES

       upssched.conf(5)