shutdown.sh

#!/usr/bin/env bash

IPGROUP="192.168.1.35 192.168.1.36 192.168.1.2"  # any number, space delimited
IPCOUNT="3"   # number of machines being tested
MAXFAILS="5"    # Total number of fails before shutdown
INTERVAL="10"   # time in seconds between tests
#If MAXFAILS is 5 and INTERVAL is 10, then you're looking at about a minute
# of all machines being down before the NAS powers off
COUNT="0"       # reset COUNTer
UPMACHINES="0"  # pass/fail indicator
DEBUG="1"       # 1 for DEBUGging, 0 for not

while [ "$MAXFAILS" != "$COUNT" ];
do
  if [ "1" == $DEBUG ]; then echo "MAXFAILS=$MAXFAILS  COUNT=$COUNT"; fi
  UPMACHINES=$IPCOUNT     # Reset indicator
  if [ "1" == $DEBUG ]; then echo "UPMACHINES=$UPMACHINES"; fi
  for IP in $IPGROUP; do # This is where the space delimiting expands to multiple parameters
  #  The variable $IPGROUP is not quoted for a reeason, do not "correct" it
    /sbin/ping -c 1 "$IP"
    if [ $? != "0" ]; then
      UPMACHINES=$((UPMACHINES-1)) #decrease number of running machines detected
      if [ "1" == $DEBUG ]; then echo "IP=$IP  UPMACHINES=$UPMACHINES"; fi
    fi
  done
  if [ 0 == $UPMACHINES ]; then COUNT=$((COUNT+1)); else COUNT="0";  fi
  # If all IPs failed, increment COUNTer, otherwise, zero it
  sleep $INTERVAL
done
echo "Shutting down. no response(s) from any of $IPGROUP"
/sbin/shutdown -p now