VMS vs. UNIX file system

Jeremy Webber jeremy at chook.ua.oz
Wed Sep 21 11:03:53 AEST 1988


In all this discussion I have not seen mention of the fact that you can open a
VMS file for block i/o and then treat it as a stream of blocks.  This can be
useful for just moving data around.  It can also be dangerous, but no more so
than treating a file as a stream of bytes.

One thing that I think DEC stuffed up badly though is that they did not define
a standard for text files.  Instead, you have variable-length-carriage-control,
Fortran carriage control, List carriage control, stream-LF, stream-CR and
probably half a dozen others that I have not thought about.  This makes writing
text file manipulation programs, such as text editors, a real pain.  It also
makes manipulation of text by programs written in different languages
hazardous.  I believe that DEC should modify the run time libraries of all
languages to convert internal text to and from a standard text form when
reading and writing files.

I can see the performance advantages of letting the file system "know" about
RMS.  Particularly with regard to record locking and other commercial uses.

In short, there are advantages and disadantages in the VMS as against the UNIX
method of treating files, and you'll probably choose the one best for your
application.

-Jeremy Webber (jeremy at chook.ua.oz.au)
Computer Science, Adelaide University, Australia

"One of these days I'll get around to writing a .signature file"



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