Summarizing dig Info with a bash script.

Dig is a great tool, but most of its output is not very interesting. There are a bunch of command line options that I can never remember without a quick ‘man dig’ which always sounds a bit odd. So I whipped up a quick script. It takes a domain name as the argument, and then pumps out the Reverse IP lookup, Nameservers, and Mail servers with reverse lookup of their IPs.

#!/bin/bash
QUERYDOMAIN=$1
echo "Reverse IP:"
 echo "    " `dig x +short $QUERYDOMAIN`
 echo "Nameservers"
 NAMESERVERS=`dig ns +short $QUERYDOMAIN | sed "s/^[0-9]* //g"`
 for SERVER in $NAMESERVERS;
 do
 echo "    " $SERVER " = " `dig x +short $SERVER`;
 done
 echo "Mail Servers:"
 MAILSERVERS=`dig mx +short $QUERYDOMAIN | sed "s/^[0-9]* //g"`
 for SERVER in $MAILSERVERS;
 do
 echo "    " $SERVER " = " `dig x +short $SERVER`;
 done

The output looks like this:

scripts/diggety.sh hp.com
Reverse IP:
15.216.110.22 15.216.110.139 15.216.110.140 15.192.45.21 15.192.45.22 15.192.45.138 15.192.45.139 15.216.110.21 15.240.238.51 15.240.238.55 15.193.112.21 15.193.112.23 15.201.49.21
Nameservers
ns1.hp.com.  =  15.219.145.12
ns2.hp.com.  =  15.219.160.12
ns3.hp.com.  =  15.203.209.12
ns5.hp.com.  =  15.195.192.37
ns6.hp.com.  =  15.195.208.12
Mail Servers:
smtp.hp.com.  =  15.193.32.72

I spent about 20 minutes writing the script, and then it just saved me about 30 minutes work when a client called, wanting to troubleshoot their mail servers over 20 domains. That’s what bash scripts are all about … hope it saves you some time too.

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