hosts file to bind zone file

hosts_to_zone.sh

#!/bin/sh
while read line; do
        ip=$(echo $line | cut -d " " -f 1);
        hosts=$(echo $line | cut -d " " -f 2-);
        zone=$(echo $hosts | tr " " "\n" | awk '{print length"\t"$0}'|sort -n|cut -f2- | head -1);
        echo "processing zone: $zone (ip $ip - hosts $hosts)";

        echo "\$ORIGIN $zone." > $zone.db;
        echo "\$TTL 1h" >> $zone.db;
        echo "$zone.  IN  SOA ns.$zone. username.$zone. ( 2007120710; 1d; 2h; 4w; 1h )" >> $zone.db;
        for host in $hosts; do
                if [ "$host" = "$zone" ]; then
                        echo "@ A $ip" >> $zone.db;
                else
                        echo "$host A $ip" >> $zone.db;
                fi
        done
done