Shell Programming and Scripting

Hi,
I am stuck while developing a shell sub-routine which checks the log file for "success" or "failure". The subroutine reads the log file and checks for key word "success", if found it set the variable (found=1). It returns success or failure based on this variable.

My problem is, I can see the variable being set to 1 (success scenario) but once it comes outside the while loop the value is reset to 0.
Here is the my logCheck function, please let me know where I am wrong.

function logCheck
{
found=0; #sets to 1 if "success" is found

cat ${OUTPUT_LOG} |
while read line
do
temp=`echo $line|grep "${SUCCESS_MESSAGE}"`
if [ $? -eq 0 ];then
found=1 <-- value is 1 here
echo "string is found"
echo "found value inside while is : $found"
fi
done

echo "found value outside while is $found" <-- found is 0 in all case
if [ $found = 1 ];then
return $SUCCESS;
else
return $FAILURE
fi
}


//output for success scenario:
string is found
found value inside while loop : 1
found value outside while loop is 0