Digging to the final IP
Jim Young
jyoung at gsu.edu
Wed Oct 22 04:46:36 UTC 2014
On 10/22/14 12:08 AM, "LuKreme" <kremels at kreme.com> wrote:
>> On 21 Oct 2014, at 19:20 , Dave Knight <dave at knig.ht> wrote:
>>
>> $ dig +noall +answer dave.knig.ht in a | egrep 'IN\tA\t' | cut -f6
>> 216.235.14.46
>
>Interesting. This works for me:
>
>dig +noall +answer home.kreme.com in a | egrep '\tA' | cut -f5
>
>but on your example, it requires -f6
>
>And yet, the outputs appear to have the same number of fields.
>
> $ dig +noall +answer www.kreme.com in a
>www.kreme.com. 21139 IN CNAME cerebus.kreme.com.
>cerebus.kreme.com. 21141 IN A 23.24.150.141
> $ dig +noall +answer dave.knig.ht in a
>dave.knig.ht. 13916 IN CNAME sb.sanxion.org.
>sb.sanxion.org. 222 IN A 216.235.14.46
>
>Very odd.
Subtle formatting difference for human consumption. There are a variable
number of ASCII TABs inserted to visually align fields.
$ dig +noall +answer www.kreme.com in a | egrep '\tA' | cat -t
cerebus.kreme.com.^I21409^IIN^IA^I23.24.150.141
$ dig +noall +answer dave.knig.ht in a | egrep '\tA' | cat -t
sb.sanxion.org.^I^I299^IIN^IA^I216.235.14.46
There is only one ASCII TAB (represented as ^I with cat -t) between
"cerebus.kreme.com." and "21409." but two ASCII TABs between
"sb.sanxion.org." and "299". I'm guessing a very short name might
result in three!
This is where output generated for human consumption can be tricky to
parse.
Best regards,
Jim Y.
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