Shell Programming and Scripting

I need some help creating a condition for looking up hosts. I have this master host file that has data in the following columns:

Code:

FQDN     primary IP     secondary IP     third IP

I need the hostnames to feed into another script I use for provisioning users. The FQDN doesn't always work for connection attempts and sometimes the hostname needs a different suffix (.svr.company.net, company.net, company.com, etc). Unfortunately this master host file is not managed by me and I do not have the ability to fix the hostnames origin in the file. However it does provide the IP's which I can look up and that gives me the appropriate FQDN. The other script in which this information is fed will only accept the hostname, not the IP.

So I run a loop to cat the master hosts file, awk for column 2, and nslookup the value at the time of the iteration. The thing I need help with is I need a condition to say "if the IP from column 2 does not resolve, try the one from column 3, and if that doesn't resolve then try the IP from column 4". I was toying with an if/else statement:

Code:

if [ nslookup $(cat line | awk -F " " {'print $2'}) | grep NXDOMAIN ]
     then try column 3
else
     proceed to the next line

I'm not really sure how it should look and I'm waiting on support so I thought I'd try here.

I would use the host command, the output is easier to parse. This is in ksh.

Code:

#!/bin/ksh    
# also works with /bin/bash
while read col1 col2 col3 col4
do
     ok=""
    for i in $col2 $col3 $col4
    do
          host $i >/dev/null
          if [ $? -eq 0 ] ; then
               ok=$i
               break          
          fi
    done
    if [ ! -z "$ok" ] ; then
         echo "we found a good one: $ok"
    else
         echo "no valid values found"
    fi
done < master_hosts

try that for a starter

This is really good - I've been working with it all week (among other things). Thank you! I have it set now to awk the ip address into a file and provide a list of exception hosts (NXDOMAIN) that need to be investigated. The only problem I have now is when "host" spits out two lines - like:

Code:

hostname is an alias for host_name
hostname has address 1.1.1.1

I think if I pipe it into a grep for "address" I should be good.