problem with rsync exclude
 

I use rsync to backup my thunderbird mail directory every night. I am tring to exclude the cache2 directory using the following command:
rsync -avzrcp --exclude '/home/xxx/.thunderbird/yc4iwpsm.default-default/cache2' /home/xxx/.thunderbird /media/nas2/xxx

In the the test, the cache2 directory (and its contents) were copied. I have obviously made a mistake but so far don't see it.

Thank you.

The exclude option uses relative paths referenced to the source directory.

Command given is missing the destination.

The destination is the xxx. The problem was, as explained by Michaelk, the exclude needs the RELATIVE directory (that is relative to overall source.) I only need the --exclude 'cache2' not its complete path.