Shell Programming and Scripting

Hi Pals

I am using this command in my script to find out warnings using fgrep where $log is the log file name, $date is the date to be searching and warnings.list contains list of matching words.

grep "WARNING" $log|grep "$date"|fgrep -vf warnings.list

I want to perform another action based on this output. i.e if any warning is found in any log file, I want to store those warnings in a temp file, if not no action.. I tried below two commands to assign the no. of warnings to a variable, but doesn't work. Can you please help me how to do this is there any other way to find out wheter below command has returned any output.
x=$(grep "WARNING" $log|grep "$date"|fgrep -vf warnings.list)
x=`grep "WARNING" $log|grep "$date"|fgrep -vf warnings.list`

The return code from fgrep indicates whether there were any matches.

Code:

if grep WARNING "$log" | grep "$date" | fgrep -vf warnings.list >/tmp/file
then
  dance and sing the /tmp/file dance
else
  : no warnings
fi
rm /tmp/file

It would perhaps be more elegant to join at least the WARNING and $date grep into a single command (probably more accurate too -- avoid spurious matches on $date for example) but that's a digression.