Exemplos de Uso
$
dig 4.3.2.1.zen.spamhaus.org
dig 4.3.2.1.b.barracudacentral.org
dig 4.3.2.1.bl.spamcop.net
$
for bl in zen.spamhaus.org b.barracudacentral.org bl.spamcop.net; do
result=$(dig 4.3.2.1.$bl +short 2>/dev/null)
echo "$bl: ${result:-limpo}"
done