Werner's excellent suggestions
Please, don't exaggerate

A suggestion with exclude something:
Code:
cd /; STOR=/mnt-system/update$(date +'%m%d%H').tar.gz
echo -e 'Compressing data; patience, this may take a little time..\n'
tar -cz --exclude=*/Cache/* --exclude=*/OfflineCache/* \
    -f $STOR KNOPPIX-DATA/home/ KNOPPIX-DATA/etc/ \
     KNOPPIX-DATA/root/  mnt-system/boot/syslinux/syslinux.cfg