[Info-vax] difference in files being copied by scp from Unix to VMS

[Richard B. Gilbert]

Sumir wrote:
> On Apr 28, 9:09 am, koeh... at eisner.nospam.encompasserve.org (Bob
> Koehler) wrote:
>> In articl03f0617$0$30920$c3e8... at news.astraweb.com>, JF Mezei <jfmezei.spam... at vaxination.ca> writes:
>>
>>
>>
>>> *whenVMSreceives thefile, it might tag on those extra bytes.
>>    Most network utilities forVMSstore binary data as 512 byte records.
>>    So if the last byte received is somewhere in the middle of the
>>    block zero padding is added after the last data byte.
>>
>>    Many of the files thatVMStreats as binary need to be 512 byte
>>    blocks, others don't.  Some network utilities allow the user to
>>    control how binary data is stored (e.g. record size in the Multinet
>>    FTP client), others don't.
>>
>>    I ran into this with an FTP binary transfer via UCX' client years
>>    ago.  We were not able to meet the customer's original requirement
>>    that we prove the receivedfileidentical to the remote copy, since
>>    it wasn't.  The customer was happy that we could prove all the
>>    bytes prior to the pad were identical, right up to the number of
>>    bytes the remote system claimed for thefilesize.
>>
>>    It is, of course, possible to fix thefileafter receipt, just not
>>    typically necessary to do so.  RMS keeps a value in thefileheader
>>    which locates the last data byte in the last disk block; or the
>>    filecan be rewritten in a different format.
> 
> 
> Hi,
> 
> the program i am looking to write is similar to the one specificed by
> you. (comparing file). so as mentioned that comparison of files
> considering the bytes prior to the pad would be sufficient too. Could
> you please share a snippet as to how this is to be achieved ( i am not
> very familiar with vms commands ), or is there a command just to
> compare two files upto certain bytes or something like that ?

There is a DIFFERENCE utility.  I don't recall that it can be made to 
stop before End Of File.  It should be sufficient that no difference is 
reported up to and including the last data byte in the file.