Interestingly the next point in my script where a file had to be manipulated exhibited the same problem - this file only had one field but the script saw just one entry eventhough there are many lines... I found that adding:
It is boc the space between sss and sss, command cat will tread them as differen lines. So below content in your script will generate three lines but not only one single line. Anyway, while loop can solve your problem.
xxxxxxxxx,yyyy,sss sss sss,bbbbbbb
while read line
do
echo $line | awk 'BEGIN{FS=","}{print $3}'
done < filename