[Info-vax] BACKUP to the null device

[Rob Brown]

On Wed, 9 Feb 2011 at 07:33 -0600, Bob Koehler wrote:

> In article 
> <alpine.LFD.2.00.1102081327020.13023 at libra.gmcl.internal>, Rob Brown 
> <mylastname at gmcl.com> writes:
>>
>> I am going to wave my hands and guess that it is because NL: is not 
>> a tape device, the only device type for which you are not required 
>> to specify "/SAVE_SET".  Let's call it an "undocumented permanent 
>> restriction".
>
>   I think it is fully documented.

I mean that this behaviour of NL: in BACKUP is undocumented.

Do you disagree?

I do not find any mention of the null device in the backup 
documentation.  The only description of the null device that I find 
anywhere is in Programming Concepts where it says:

   Reads from NL: return end-of-file
   Writes to NL: return success

In my mind, BACKUP's behaviour with NL: does not follow naturally from 
this.  There must be some code that decides what to do with the null 
device.  Philip's subsequent replies make me think that it is not as 
simple as "it's not a tape so it must be a disk".

But I'm still just waving my hands hoping to attain flight.


-- 

Rob Brown                        b r o w n a t g m c l d o t c o m
G. Michaels Consulting Ltd.      (780)438-9343 (voice)
Edmonton                         (780)437-3367 (FAX)
                                  http://gmcl.com/