#!/bin/bash
ip='192.168.0.19'
mail=aiker@gzedu.ml
while true
  do
      ping -c4 $ip  > /dev/null
      if [ $? -ne 0 ]
         then
               echo "`date +%F-%T` $ip is down" | mail -s " $ip is down" $mail
      fi
      sleep 30
  done