How to use dig with an ip list

[Wayne Sierke]

On Mon, 2008-08-18 at 22:52 -0500, Paul Schmehl wrote:
> --On August 18, 2008 10:13:54 PM -0500 Jeffrey Goldberg 
> <jeffrey at goldmark.org> wrote:
> 
> > On Aug 18, 2008, at 9:03 PM, 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?
> >
> > Easiest:
> >
> > $ for i in `cat ip-list`; do
> >  > echo -n "$i "
> >  > dig +short -x $i
> >  > done
> >
> 
> Don't know why I didn't think of that.
> 
> I ended up using this:
> for ip in `cat public_linux_ips`; do echo ${ip} `dig +short -x ${ip}`; 
> done > public_linux_ips_resolved
> 
> Which gave me the output I wanted.  Thanks for the pointer.
> 
Easiestest?

        # host www.freebsd.org
        www.freebsd.org has address 69.147.83.33
        www.freebsd.org has IPv6 address 2001:4f8:fff6::21
        www.freebsd.org mail is handled by 0 .
        # host ftp.freebsd.org
        ftp.freebsd.org has address 62.243.72.50
        ftp.freebsd.org has address 204.152.184.73
        ftp.freebsd.org has IPv6 address 2001:6c8:6:4::7
        ftp.freebsd.org has IPv6 address 2001:4f8:0:2::e
        # cat > freebsd.ips
        69.147.83.33
        62.243.72.50
        204.152.184.73
        # host 69.147.83.33
        33.83.147.69.in-addr.arpa domain name pointer www.freebsd.org.
        # awk '{ip=$1; "host "ip | getline; print ip,$NF }' freebsd.ips
        69.147.83.33 www.freebsd.org.
        62.243.72.50 ftp.beastie.tdk.net.
        204.152.184.73 freebsd.isc.org.

s/host/dig/ to taste

The middle command - "host "ip | getline; - executes the 'cmd' part on
the left side of the pipe, getline parses the output, hence $NF now
gives the last field in the output from "host".


Wayne
(You don't know the power of the awk side!)