[Info-vax] wrong file format

[Dirk Munk]

Bill Gunshannon wrote:
> On 12/31/20 6:07 AM, Dirk Munk wrote:
>> Bill Gunshannon wrote:
>>> On 12/30/20 7:59 AM, Dirk Munk wrote:
>>>> Jan-Erik Söderholm wrote:
>>>>> Den 2020-12-29 kl. 23:05, skrev Dirk Munk:
>>>>>> Bill Gunshannon wrote:
>>>>>>> On 12/29/20 9:21 AM, Jan-Erik Söderholm wrote:
>>>>>>>> Den 2020-12-29 kl. 14:35, skrev Phillip Helbig (undress to reply):
>>>>>>>>> In article <rsfarr$smk$1 at dont-email.me>, Dirk Munk <munk at home.nl>
>>>>>>>>> writes:
>>>>>>>>>
>>>>>>>>>>> I tried for about 45 minutes---all the suggestions posted 
>>>>>>>>>>> here! It was
>>>>>>>>>>> about 100 MB, so not all were quick to check.
>>>>>>>>>>>
>>>>>>>>>>> In the end, I managed to transfer it again (don't ask!) and 
>>>>>>>>>>> somehow,
>>>>>>>>>>> magically, it was OK.
>>>>>>>>>>>
>>>>>>>>>> I've dealt with problems like these before, usually caused by
>>>>>>>>>> applications that were not written for VMS.
>>>>>>>>>>
>>>>>>>>>> You need to have a bit of a feeling for the different file 
>>>>>>>>>> types of VMS
>>>>>>>>>> to fix these problems, but if you have that, it's very simple 
>>>>>>>>>> to solve
>>>>>>>>>> these little puzzles.
>>>>>>>>>
>>>>>>>>> I don't know how many times I've used SET FILE/ATTR or CONVERT 
>>>>>>>>> or TECO
>>>>>>>>> to fix things like this.  I can usually look at the contents, 
>>>>>>>>> look at
>>>>>>>>> DIR/FULL, and see what needs to be done if they don't match, 
>>>>>>>>> but this
>>>>>>>>> was somehow different.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Nice that it was fixed! And no, I do not belive in magic... :-)
>>>>>>>
>>>>>>>
>>>>>>> And, just so people don't think, based on earlier comments, that
>>>>>>> Unix is somehow immune, I frequently have to remove "^M" characters
>>>>>>> from text files on Unix. Unix's only saving grace in this regard is
>>>>>>> that the solution is trivial.  :-)
>>>>>>>
>>>>>>> bill
>>>>>>>
>>>>>> No, of course Unix is not immune. Using <lf> or <cr> (Windows) as 
>>>>>> record terminator is a rather silly idea. It means that you can't 
>>>>>> use those characters in a record, and you have to scan the 
>>>>>> contents of a file for those characters. Simply writing the length 
>>>>>> of a record at the beginning of that record is far better solution.
>>>>>
>>>>> Having a <LF> or a <CR> in text files seems rather logical to me.
>>>>> What else, if you want either a line feed or a carriage return?
>>>>>
>>>>> But yes, there are other ways to specify and delimiting a "line of 
>>>>> text",
>>>>> if you have a system suporting that.
>>>>>
>>>>> Now, if that "record" is something else than a "line of text"...
>>>>>
>>>>>
>>>>
>>>>
>>>> The problem is that in Unix and Windows land there is no difference 
>>>> between the metadata of a file, and the actual contents of a file. 
>>>> The metadata should define the file and the records in the file, 
>>>> that should be completely separate from the actual data contents of 
>>>> the file.
>>>
>>> Can't speak for Windows, but Unix has no meta-data. Unix has only one
>>> file type, a stream of bytes.  Everything else is application layer.
>>
>> Which means you don't have a clue about the contents of a file, until 
>> you know the internals of the application. 
> 
> Well, that isn't exactly true.  Certain file types do have clues.
> And, at least under Unix, there is an application that will do a
> very good job of identifying what the file is.  It is even possible
> to add your own hints if they exist and if you so desire .

Nice, but suppose you have a Cobol compiler on Unix, then it will have 
to set up its own file system with all the files Cobol supports, like 
indexed files. What will that application do with those files? RMS will 
tell you the structure of the file, you don't have to guess it.

> 
>>                                            Standard VMS applications 
>> produce structured files, so you only have to worry about the data 
>> contents. It is possible to write your own applications using the 
>> files of another application. The application can be in any language, 
>> because RMS is the layer between the application and the file. This is 
>> a structured approach, instead of producing a diarrhea of bytes, and 
>> calling it a file.
>>
>>>
>>>>
>>>> Suppose I have a file with binary data, and one byte has the binary 
>>>> (ascii) value of <lf>, then Unix will use it as a record separator, 
>>>> even if it is in the middle of the actual data of that record.
>>>
>>> Unix has no records. If you cat the file it will line break at the <lf>.
>>> If you od -c the file it will identify the <lf> as just that.
>>>
>>
>> Wonderful. However, it is clear that in many applications the notion 
>> of a data record is present, and that the <lf> is used as record 
>> separator, even if Unix formally doesn't have records.
> 
> Again, that is  more of a C'ism than a Unix'ism.  If I write an
> application that uses ^M instead of ^J it will work just fine.
> and, there is no reason why I couldn't have ^J as a valid, non-
> record terminating character in the file.

Sure you can. But the standard (used for instance by FTP ASCII 
transfers) is <lf>.

> 
>>
>>>>
>>>> Suppose you have a VMS file with fixed record size. That file has no 
>>>> records separators what so ever, it is one long stream of data. VMS 
>>>> can calculate where the records start and end in the file. Suppose 
>>>> it consists out of sets of three records of 100 bytes that belong 
>>>> together. Then you can change the attributes of that file to records 
>>>> of 300 bytes, and in one read operation you will have all the data 
>>>> that belongs together. I've actually used this in the past.
>>>
>>> And that would be an application concept, not really an OS thing.
>>
>> Actually not, since this can only be done because of the way RMS 
>> stores data, and RMS is part of the OS.
> 
> See, there is where we differ in opinion.  I see RMS as an
> application that just happens to ship with VMS.  Like editors,
> compilers and other pieces that ship with the OS but have are
> not really part of it.  Surely VMS will run without RMS present.
> Not all applications need to access files at all.

No, RMS is more like middleware. How do you think that VMS could read 
and write its own files if RMS is not present?

> 
>>
>>>
>>>>
>>>> Suppose you want to print such a file, then VMS will send a <cr> and 
>>>> a <lf> to the printer after each record. Simple.
>>>
>>> VMS won't.  Whatever application actually prints it will.
>>>
>>
>> Obviously, this is functionality of the spooler, and that is part of VMS.
>>
>>>>
>>>> The DEC software engineers understood very well why it is a bad idea 
>>>> to mix up contents of a file with the structure of a file, and 
>>>> that's why they did not use stream files as standard RMS files in 
>>>> applications. They are just there for compatibly with Unix, Windows 
>>>> etc.
>>>
>>> And Unix made all files streams of bytes and lets the applications
>>> decide what to do with them.  Not really an OS problem.
>>>
>>
>> Exchanging data between applications is rather important. Those 
>> applications can be written in many languages, can come from different 
>> sources. It is obvious that well structured files are paramount for 
>> exchanging data between applications. That is why something like RMS 
>> is in fact a very modern approach to structured software engineering, 
>> instead of producing a an unstructured diarrhea of bytes, and calling 
>> it a file.
> 
> Some see it otherwise.  Unix tends to leave more control for the
> developer and not try and handcuff them with someone else's concept
> of how things should be done.
> 

If you must, you can do that with VMS as well. However, in 99.9% of all 
applications, RMS with all of its functionality will give you execly 
what you need. The point is, Unix doesn't have something like that. With 
VMS you have the choice, with Unix, you don't.