check logfiles script

Not so generic way to check ‘any’ logfile for erros
I have written at least about 5 variations of this same script. Some more flexible and genereal purpose.
But in the end I have been writing customs made out of this skel.
What usually needs change: date formatting, key errors.

#!/bin/bash
# script to check how many key in the current hour
# Felipe Ferreira June 2012
# updated April 2013
#important to check your log date/time stamp format, it changes from log to log so you will need to get it right
#if you are interested in only getting statistics, its better to use last hour, this way you have consistent number
#if you need to get the error right when it happens its better to use the now hour
#possible bugs: it will keep showing that you have an error for an entire hour...
DIA=`date +%d`
MES=`date +%b`
HORA=`date +%H`
#HORA=`date +%H -d  "1 hour ago"` #ultima hora
tday="$MES $DIA $HORA"
KEY="OutOfMemoryError"
LOGFILES="/opt/tibco/tra/domain/PRD/application/logs/*.log"
if [ "$2" == "" ]
then
  echo -e "\n Syntax: $0   \nex.: $0 50 900 \n O script retoran a qunatidade de erros nesta hora \n"
  exit 3
fi
warn=$1
crit=$2
#debug
#echo "DATE: $tday"
#echo "grep $tday $LOGFILES |grep -c $KEY"
ERROS=`grep "$tday" $LOGFILES |grep -c "$KEY"`
MSG="Existem $ERROS erros do tipo $KEY as $HORA horas|ERROS=$ERROS"
if [ $ERROS -ge $crit ]; then
 echo "CRITICAL - $MSG"
 exit 2
elif [ $ERROS -ge $warn ]; then
 echo "WARNING - $MSG"
 exit 1
else
 echo "OK - $MSG"
 exit 0
fi