Log Monitor

logmonitor.sh

#!/bin/sh

if [ $# -eq 0 ]; then
	echo "Usage: ./monitor.sh /my/log/file.log"
fi

if [ $# -eq 1 ]; then
	LOGFILE=$1
fi

echo "Monitoring $LOGFILE"

AFILE="/tmp/monitor.log.a"
BFILE="/tmp/monitor.log.b"
KEEPDIFFING=1
SLEEPTIME=2

echo "Please wait, setting up monitoring"
tail $LOGFILE > $AFILE
sleep 1
tail $LOGFILE > $BFILE
echo "Monitor files ready"
echo "Checking logfile differences every second, will stop script once no changes are detected"
echo -n "Start at: " && date

while [[ $KEEPDIFFING -eq 1 ]]; do
	DIFFCMD=`diff -q $AFILE $BFILE`
	if [[ "Files $AFILE and $BFILE differ" == "$DIFFCMD" ]]; then
		echo -n "." #Progress indicator that the script is running.
	 	KEEPDIFFING=1;
	 	tail $LOGFILE > $AFILE
	 	sleep $SLEEPTIME;
	 	tail $LOGFILE > $BFILE
	else
		echo "No update to log file in last $SLEEPTIME second(s), stopping script"
		echo -n "Stopped at: "
		date
		KEEPDIFFING=0
	fi 
done