How to use dig with an ip list

[Paul Schmehl]

--On August 19, 2008 12:44:05 PM +1000 Fraser Tweedale <frase at frase.id.au> 
wrote:

> On Mon, Aug 18, 2008 at 09:03:36PM -0500, Paul Schmehl wrote:
>> I know I'm missing the obvious.  I want to use an IP list to generate
>> an  ip+hostname list.  IOW, I want to go from this:
>>
>> x.x.x.x
>> y.y.y.y
>>
>> to this;
>>
>> x.x.x.x foo.domain.tld
>> y.y..y.y bar.domain.tld
>>
>> What's the best/easiest way to do this?
>>
>> Paul Schmehl (pauls at utdallas.edu)
>> Senior Information Security Analyst
>> The University of Texas at Dallas
>> http://www.utdallas.edu/ir/security/
>
> dig(1) - see section `MULTIPLE QUERIES'
> note the -x flag to instruct dig to perform a reverse lookup
>
> see also host(1)
>

That's not a great deal of help.  I, of course, had read and re-read the 
man pages before posting the question here, and I'm quite familiar with 
the "normal" use of dig and host, because I use them daily in my work.

The two options that man (1) dig provides are; on the commandline and in a 
file.  I can easily generate a list of hostnames having constructed an 
iplist in a file and then preceding each line with "dig +short -x IP" 
using vi.  But that gives me a list of hostnames only.  What I'm looking 
for is the combination of the two. host (1), of course, doesn't even have 
*those* options, so it's of no use for accomplishing what I'm attempting.

Again, I want to start with a list of IPs and end up with a list of IPs 
*plus* their hostnames (on the same line).  I'm quite sure someone here 
has the experience and/or knowledge to do this using shell commands.  I 
suspect awk might be helpful but haven't yet investigated that angle.

Paul Schmehl (pauls at utdallas.edu)
Senior Information Security Analyst
The University of Texas at Dallas
http://www.utdallas.edu/ir/security/