#!/bin/sh
#
# Monitor file $1 for changes
# Send an alert email to $2 if file $1 changes
# usage: filewatcher {file_to_watch} {your_email_address}
#

if [ -z "$2" ]; then
    echo "Usage: filewatcher {file_to_watch} {your_email_address}"
    exit 1
fi

#if a inotifywait for this file is already running
if [ $(ps aux | grep inotifywait | grep -c "$1" ) -gt '0' ]; then
        echo "A process monitoring the file $1 is already running: $(ps aux | grep inotifywait | grep "$1" )";
        exit 1;
fi

#if inotifywait exists
type -P inotifywait &>/dev/null || { echo "Error: This script requires inotifywait(http://wiki.github.com/rvoicilas/inotify-tools/) .... apt-get install inotify-tools ... " >&2; exit 1; }

#if the file exists
# if [ -f $1 ]; then

echo "Monitoring file $1 for changes - sending alerts to $2"

while inotifywait -e modify -e attrib -e move -e delete $1 -o /opt/filewatcher/audit.log; do
        sleep 1

        changes="$(tail -1 $1)"

        #changes="$(cat /opt/filewatcher/audit.log)"
        echo "The following change occurred in the file $1 : $changes" | mail -s "Change in $1" $2
        rm /opt/filewatcher/audit.log
        touch /opt/filewatcher/audit.log
        done
else
        echo "Error: File $1 not found"