OS: SOlaris 8

I am monitoring my system to periodically check network performance
(e.g. DNS lookup) using a script like this:

while true;
do
echo $(date) >> $OUTPUT_FILE
time nslookup www.sun.com | grep real >> $OUTPUT_FILE
sleep 30
done

but the grep and the output redirections does not seem to work? Any
suggestion (I am not very familiar with the 'time' command).