Event Drivern Shell Script :) If something is written in a log file, a processe starts.

logwatch.sh

PATH="/bin:/usr/bin:/usr/local/bin"
export PATH
 
FILE="/var/log/syslog"
PATTERN="warn"
SUBJECT="ALERT-LOGWATCH"
MAIL_TO="hogehoge@example.co.jp"

tail -n 1 --follow=name $FILE | while read INPUT; do
 echo "$INPUT" | grep "$PATTERN" > /dev/null
 RET=$?
 if [ "$RET" == "0" ]; then
  echo "$INPUT" | mail -s "$SUBJECT" "$MAIL_TO"
 fi
done