Don't delete jail content on error, cleanup

Don't delete jail content on busy datasets by default, cleanup.

usr/local/share/bastille/destroy.sh

@@ -77,8 +77,12 @@ destroy_jail() {
                         if [ "${FORCE}" = "1" ]; then
                             OPTIONS="-rf"
                         fi
-                       ## remove jail zfs dataset recursively
+                        # Remove jail zfs dataset recursively, or abort if error thus precerving jail content.
-                        zfs destroy "${OPTIONS}" "${bastille_zfs_zpool}/${bastille_zfs_prefix}/jails/${_jail}"
+                        # This will deal with the common "cannot unmount 'XYZ': pool or dataset is busy"
+                        # unless the force option is defined by the user, otherwise will have a partially deleted jail.
+                        if ! zfs destroy "${OPTIONS}" "${bastille_zfs_zpool}/${bastille_zfs_prefix}/jails/${_jail}"; then
+                            error_exit "Jail dataset(s) appears to be busy, exiting."
+                        fi
                     fi
                 fi
             fi
@@ -198,9 +202,9 @@ destroy_rel() {
 }
 
 # Handle options.
-AUTO=0
+AUTO="0"
-FORCE=0
+FORCE="0"
-NO_CACHE=0
+NO_CACHE="0"
 while [ "$#" -gt 0 ]; do
     case "${1}" in
         -h|--help|help)