Self-adaptive script for the drives

Replace this:

drives="da0 da1 da2 da3 da4 da5 da6 da7"

by this :

drives=$(for drive in $(sysctl -n kern.disks); do \
if [ "$(smartctl -i /dev/${drive} | grep "Serial Number" | awk '{print $3}')" ]
then printf ${drive}" "; fi done | awk '{for (i=NF; i!=0 ; i--) print $i }')