這是一段描述如何找出名單中已成功設定domain name 指向 140.128.53.34 的script

ipv4

#!/bin/bash
filename='list.txt'

exec < $filename

while read line
do
        nslookup $line | grep 140.128.53.34
        if [ $? == 0 ]
        then
                echo $line >> ok_result.txt
        fi
        sleep 1
done

grep 符合字串成功的回傳值為 0

藉由 $?  可以得知回傳值

ipv6 使用dig

#!/bin/bash
filename="list.txt"
ipv6="2001:288:5400:d::34"

exec < $filename

while read line
do
        #dig lxes.tc.edu.tw AAAA | grep 2001:288:5400:d::34
        dig $line "AAAA"| grep $ipv6
        if [ $? == 0 ]
        then
                echo $line >> ok_result6.txt
        fi
        sleep 0.5
done