APC UPS control system

This ﬁnal step is important if you want to ensure that your system

will automatically reboot when the power comes back on. The actual

code used on the Red Hat version is:

# See if this is a powerfail situation. # ***apcupsd***

if [ -f /etc/apcupsd/powerfail ]; then # ***apcupsd***

echo # ***apcupsd***

echo "APCUPSD will now power off the UPS" # ***apcupsd***

echo # ***apcupsd***

/etc/apcupsd/apccontrol killpower # ***apcupsd***

echo # ***apcupsd***

echo "Please ensure that the UPS has powered off before rebooting" # ***apcupsd***

echo "Otherwise, the UPS may cut the power during the reboot!!!" # ***apcupsd***

echo # ***apcupsd***

fi # ***apcupsd***

The above code must be inserted as late as possible in the halt script. On

many systems, such as Red Hat, all the disk drives were unmounted, then

remountedread-only, thus permitting access to the /etc ﬁles andthe apcupsd

executable. If your system does not explicitly remount the disks, you must

remountthem in read-only modein the code that you add. Examples of code

fragments that do this can be found in the distributions/suse subdirectory

of the source.

If you are not able to insert the aboveco de inyour halt script because there

is no halt script, or because your halt script calls the init program as some

Unix systems do, you can either just forget about powering oﬀ the UPS,

which means that your machinewill not automatically reb oot after a power

failure, or there is yet another alternative, though not at all as satisfying as

inserting code in the halt script.

Only if you cannot insert the appropriate code in the halt script, when

you start apcupsd, normally from the /etc/rc.d/init.d/apcupsd script, use

the --kill-on-powerfail option. This will cause ap cupsd to program the

UPS to shutoﬀthe p owerjust before it (apcupsd) do es the system shutdown.

Please note that this is not the most ideal solution. Read on to understand

why.

A very important consideration is that you must set the EEPROMin your

UPS so that it waits a suﬃcient time for the system to halt before it shuts

oﬀ the UPS power. The current value as well as the permitted values for

your UPS can be determined by executing:

apcaccess eeprom

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