Plugin for apcupsd to prevent low battery shutdown when external DC source is connected

doshutdown

#!/usr/bin/env python

# Prevent shutdown when batteries are not really empty
# installed in /etc/apcupsd/ as 'doshutdown' and 'mainsback' (symlink)
import os
from sys import argv
from subprocess import check_output
from syslog import syslog

threshold=24.3 # If batteries are above this, don't shut down 
apcupsd_restart_command=['service', 'apcupsd', 'restart'] #adjust to your needs
marker_file='/etc/apcupsd/shutdown_prevented'

def log(str):
    syslog('%s: %s' % (argv[0], str))

# behavior determined by script name:
if "doshutdown" in argv[0]:
    voltage=float(check_output(['apcaccess', '-p', 'BATTV', '-u']))
    log('Voltage is %s' % voltage)
# if there was a prior marker file, remove it
    if os.path.isfile(marker_file):
        os.remove(marker_file)
# prevent shutdown if batteries are not actually low:
    if voltage > threshold:
        log('Above threshold of %s, preventing shutdown' % threshold)
        open(marker_file,'a').close() # touch a file
        exit(99) #prevent shutdown
elif "mainsback" in argv[0]:
    if os.path.isfile(marker_file):
        log("Cleaning up prevented shutdown by restarting apcupsd")
        os.remove(marker_file)
# this was a prevented shutdown.  apcupsd is in a weird state now, so let's restart it
# this will also remove /etc/apcupsd/powerfail marker file:
        check_output(apcupsd_restart_command)