Emergency UNIX and Linux Support

tail -f EssbaseLog.txt
will run forever and will present lines as they are added to the file. Thus your script will run forever too. You run your script once and let it find errors as they occur.

You didn't use --follow=log-file but you may need it. Post the output from:
uname -a
so folks know what version of unix you have.

Code:

ReadLines=0
while [ true ]
do
TMPVAR=$(date +%s)
Totallines=$(wc -l /var/log/YOU.log )
Totallines=$((Totallines-ReadLines))
tail -n $Totallines /var/log/YOU.log | grep -A 50 'PATTERN' > /tmp/$TMPVAR.tmpfile
if grep 'username' /tmp/$TMPVAR.tmpfile ;
 then
   mail -s failure xxxxx@yyy.com < /tmp/$TMPVAR.tmpfile
fi
rm -rf /tmp/$TMPVAR.tmpfile
sleep 900
done

Some concept .. You need to just check with syntax to suit your system.

Basically what I am trying
While [ true ] ---> infinate loop
TMPVAR ... just to create tmp file...
Checking number of lines now and subtracting from what we have previously read. So that we dont want to send error which we have seen already ..
Tail -n ... read only last lines ... what we have not read from previous run .. And check patten and get lines matching above matching pattern.
Then again grep in the 50 lines from PATTERN which are in tmp file .. to see if username is available or not ..

if Available then mail .. else ... Nothing ..
Cleanup: remove all tmp file etc .. and sleep for 900 sec 15 mins ..

Better place to put this check is in cron:

Incase you decide to put in cron removing while do ... then push this number to some tmp file .. Like records read and etc ..
Also make note of more details in the same tmp where number of records are saved.. details like log file creation date etc to reset ReadLines variables incase the log gets rotated .. truncated etc ...


When you change PATTERN and username for your system .. Please add proper escape character wherever applicable

1. Use crontab to run every fifteen minutes, key "man crontab" in shell.

2. This script may work <script.sh <your text to grep>:

#!/usr/bin/ksh

thelog="/your/local/logpath"
user=$1
lines="50"

run () {

num1=$(cat -n $thelog |grep $1 |awk '{print $1}' |head -1)
num2=$(expr $num1 - $lines)


if [ $num1 -gt 50 ]
then
results=$(cat -n $thelog |sed -n "$num2,${num1}p")

else
results=$(cat -n $thelog |sed -n '1,50p')

fi
echo "$results" |mailx -s "blabla" yourmailbox@nospamplease.com
}


run $user;