Bash, convert IP address in batch

Question

I wanna convert a list of domain to the IP address using bash scripts in OSX.

I created a list file to present the domain line by line like this

www.google.com
www.yahoo.com
www.facebook.com

I used the following scripts to lookup the IP address:

#!/bin/bash
while read -r domain
do
    echo `dig +short $domain` 
done < list

where list is a file that contains those domain.

However, it end up only show a empty string.

But when I only query one domain, the command is okay.

dig +short www.google.com
> 216.58.221.132

Hope anyone can help me to figure out the problem. Thanks!

Why don't you drop the `echo` part and just perform a `dig +short $domain`? The `echo` is probably returning the return value of the call of `dig`. — fedorqui, Jul 18 '15 at 16:23
I tried to drop the echo part and it also returned empty string — Johnny Wong, Jul 18 '15 at 16:50
Without changing anything, your example works fine for me in OSX... — cyang, Jul 18 '15 at 17:04

cyang · Accepted Answer · 2015-07-18T17:25:50.680

dig has the -f command line option to read a list of domain names from a file. From the manpage,

The -f option makes dig operate in batch mode by reading a list of lookup requests to process from the file filename. The file contains a number of queries, one per line. Each entry in the file should be organized in the same way they would be presented as queries to dig using the command-line interface.

Running

dig +short -f list

where the file named list contains

www.google.com
www.yahoo.com
www.facebook.com

will give you output like

74.125.239.114
74.125.239.112
74.125.239.116
74.125.239.113
74.125.239.115
fd-fp3.wg1.b.yahoo.com.
206.190.36.45
206.190.36.105
star.c10r.facebook.com.
31.13.77.6

The answer is perfect! Thank you! – Johnny Wong Jul 18 '15 at 17:20 — Johnny Wong, Jul 18 '15 at 17:20

Bash, convert IP address in batch

1 Answers1