pinger

#!/bin/bash
#
# Simple ping testing script
# By: Dan Pasanen
#
# Designed to be run as a cron job
#

# A space-separated list of hosts to monitor
hosts="rpi shrew invisiblek.org"

emailto="dan.pasanen+alert@gmail.com,3202662751@vtext.com"
emailfrom="pinger@mosquito.bandit.pug"
emailsubject="Pinger"

tmpfile="/tmp/pinger.tmp"
[ -f $tmpfile ] || touch $tmpfile

for host in $hosts; do
    emailmsg=""

    if ! fping $host > /dev/null; then
        if ! grep -Fxq "$host" "$tmpfile"; then
            emailmsg="$host went down!"
            echo -ne "$host" >> "$tmpfile"
        fi
    else
        if grep -Fxq "$host" "$tmpfile"; then
            emailmsg="$host is back up!"
            sed -i 's|'"$host"'||g' $tmpfile
        fi
    fi

    [[ "$emailmsg" != "" ]] && sendemail -f "$emailfrom" -t "$emailto" -u "$emailsubject" -m "$emailmsg"

done