ups_monitor.sh

#!/bin/bash

PING_COUNT=10
INFO_LOG=/var/log/ups_monitor.log
ERROR_LOG=/var/log/ups_monitor.err
STATUS_LOG=/tmp/ups_monitor.log
SHUTDOWN_LOG=/var/log/ups_monitor_shutdown.log
LOCKER=/tmp/ups_monitor.lock
SHUTDOWN_COUNTER=5

exec 1>$INFO_LOG;
exec 2>$ERROR_LOG;

if [ -f $LOCKER ]; then
  echo "I'm running in another process"
  exit 0;
fi

touch $LOCKER

shutdown_myself() {
  echo "shuting down system..."
  echo `date` >> $SHUTDOWN_LOG
  shutdown -hP now
}

update_status() {
  echo "Updating status '$1' to $STATUS_LOG"
  touch $STATUS_LOG
  counter=`cat $STATUS_LOG`

  if [ $1 = "online" ]; then
    echo > $STATUS_LOG
    return 0
  fi

  if [ $1 = 'offline' ]; then
    if [[ $counter ]]; then
      counter=$(($counter+1));
    else
      counter=1;
    fi
    echo "  counter is $counter"
    if ((counter >= SHUTDOWN_COUNTER)); then
      shutdown_myself
    else
      echo $counter > $STATUS_LOG
    fi
    return 0;
  fi

  return 1;
}

if [[ $1 ]]; then
  gateway=$1
else
  gateway=`route -n | grep -e 'UG'|awk '{ print $2 }'`
fi
echo Gateway is $gateway

ping_failed=`ping -c $PING_COUNT ${gateway}|grep '100% packet loss'`

if [[ $ping_failed ]]; then
  update_status 'offline'
else
  update_status 'online'
fi

rm $LOCKER