dig - Feed Content of a File to a Bash Script

I'm trying to construct a script that will run a command using the contents of two files, and append the results of that command to another file.

My two files:

1. nameservers - contains the addresses of my DNS.


2. hostnames - contains hostnames that needs to be resolved against the nameservers.

I need to pass the contents of nameservers and hostnames to this command:

dig @[content of nameservers file] -t a [content of hostnames]

Then each run it will extract the query time value and append it into a file in the following format:

[nameserver1] [query time value]

Like:

1.1.1.1 100
2.2.2.2 120
3.3.3.3 115

Answer

here is a way:

#!/bin/bash
hostnames=`cat hostnamesfile`
cat nameserversfile | while read n; do
  echo "$hostnames" | while read h; do
    echo -n "$n "
    dig @$n -t a $h | grep 'Query time' | grep -o '[0-9]\+'
  done

done > resultsfile