Monitor Uptime and Alert on OpenWrt

#!/bin/ash
# Uptime monitoring for OpenWrt
# Tested on OpenWrt Attitude Adjustment 12.09
# Written By justhrun posted on <http://www.techrapid.co.uk>
# ----------------------------------------------------------
# Last Modified : 02/08/2014
# ----------------------------------------------------------

TCHECK=`date "+%Y-%m-%d %H:%M:%S"`
HOSTS="192.168.1.1 192.168.1.4 www.google.com"
xping=/usr/bin/fping
flog=/tmp/log/hostcheck.log
FPATH=/tmp/log
for myHost in ${HOSTS}
do
    filenya=${FPATH}/${myHost}.txt
    if ${xping} -q -t750 ${myHost} ; then
        ## host alive, check then remove file host.txt
        if [ -f ${filenya} ]; then
            echo "${TCHECK} : ${myHost} is BACK UP" >> ${flog}
            echo -e "Subject: [Uptime Monitor] $myHost is back up!\r\n\nGood News -- $myHost is back up" |msmtp --from=default -t destination.address@gmail.com
            rm -f ${filenya}
        fi
    else
        ## host down, check then create file host.txt
        if [ ! -f ${filenya} ]; then
            ## not exist, host is dwon
            echo "${TCHECK} : ${myHost} is DOWN" >> ${flog}
            echo -e "Subject: [Uptime Monitor] $myHost is down!\r\n\nBad News -- $myHost is down" |msmtp --from=default -t destination.address@gmail.com
            touch ${filenya}
        else
            ## exist, still down, logging don't send email
            echo "${TCHECK} : ${myHost} is still DOWN" >> ${flog}
        fi
    fi
  done

#-EOF