[plt-scheme] dns-find-nameserver complains "input in flex scanner failed" (but works anyway)

From: Thomas Holubar (scheme at phirho.com)
Date: Sun Mar 14 19:37:08 EDT 2010

Run "nslookup", in its prompt type "help" - you should be given a short 

On 15.03.2010 00:01, Eli Barzilay wrote:
> On Mar 14, Greg Hendershott wrote:
>> With DrScheme, version 4.2.3 [3m], Language: Module.
>>   (require net/dns)
>>   (dns-find-nameserver)
>> Gives the output:
>> "input in flex scanner failed" (red italics)
>> <blank line>
>> "d.d.d.d" (a valid IP address for the name server)
>> In other words it gives this error message, but dns-find-nameserver
>> and the other net/dns functions that a nameserver seem to work fine
>> anyway.
>> This is on Windows 7 64 bit. No such error message on OSX 10.6.
>> What feels like a dumb question:
>> What exactly is this red italic text? It doesn't seem to be from
>> (error) because execution continues past it. It doesn't seem to be an
>> exception because I tried catching it. What is it?
> Any output to standard error is colored like that by drscheme.
> Looking at the code, it simply runs "nslookup.exe" -- so it might be
> some problem with the windows nslookup.  My guess is that running
>    nslookup.exe<  NUL
> will show that error but still write the correct address, and to test
> that the error is printed on stderr,
>    nslookup.exe<  NUL>  NUL
> would show just the error.
> FWIW, on XP it just prints out the expected text with no error.  I
> tried to find some documentation on how to use nslookup on windows and
> found nothing.  ("help nslookup" doesn't work, "nslookup /?" or
> "nslookup /help" doesn't work, the MS web page that I found --
> http://technet.microsoft.com/en-us/library/bb490950.aspx didn't have
> anything that worked -- it mentioned some subcommands but nothing that
> I tried worked.)

Posted on the users mailing list.