VMS: logicals UNIX: links, but...

[Paul Houtz]

ok at quintus.UUCP (Richard A. O'Keefe) writes:

>Houtz's basic point is that there are lots of programs with hardwired
>file names in them, and that there is a practical need for something
>much more like logical names than Torek's recommended substitutes.

>I take leave to doubt this.  It has always been good style in UNIX
>for programs to read from standard input and write to standard output,

Okay, let me put it to you from my perspective.   I AGREE with you if
you are talking about programs that are designed on a Unix system.
However, I work in a center who's main focus is to port software from
non-unix platforms to unix.   Now, none of these software packages are
designed on unix systems.   Therefore, they aren't designed to write
to stdout, because there ain't any stdout.

There are far more applications running on IBM, VMS, MPE, etc., platforms
than unix. 

If Unix is to be THE operating system of the future, it is going to have
to make an effort to accommodate the billions (sorry Carl) of lines of
application code that exists for those systems.  All of those systems allow
you to associate a LOGICAL or VIRTUAL file name with a PHYSICAL file name.
It doesn't seem like such an illogical thing for an OS to do.   There are
perfectly good General Ledger systems out there by Price Waterhouse, 
Arthur Anderson, and there are thousands of people who already know how
to use them.  It is absurd to say that you are going to redevelop all new
GL systems and retrain users because unix doesn't have LOGICAL file names.
It also absurd to say that you are going to redevelop all applications that
weren't originally developed on unix because they don't use good unix
programming conventions. 

It would seem to me that in this case, unix is Mohammed, and that huge pile
of application software is the mountain.  Now, do you want to make the
mountain move to mohammed?   I can tell you what will happen.   Companies
have enormous investments in this software, and they don't wan't to change
source or go to enormous trouble to modify JCL to get to unix.  So many 
won't.   It would be much easier for all this IBM, VMS, and MPE software
to move to unix if this BASIC functionality was there.   Which is more
economical, as the say goes, moving Mohammed or the Mountain?   At best,
you are going to have many software developers spending man-years implementing
tedious fixes like the one Torek recommends.   At the worst, you are 
going to have 14 different versions of LOGICAL file names, a different 
one implemented by every vendor of Unix systems.

You say there are conceptual problems in using VMS logicals.  Are you 
so sure there are no conceptual problems in using unix?  How about 
aliases?   Concievably you could alias one command to another and
then that command to the first command.   The same EXACT conceptual
problem you mention with logicals.   Unix solves it simply by not
allowing it.  No problem.  You could do the same with logical file
names.   Don't allow recursive definitions.   However if you say there
is a conceptual problem there, then it is there JUST THE SAME problem with 
unix aliases.

Finally, when I hear people tell me that unix SHOULDN'T do something, I 
wonder just who is playing God.  It sounds like a circular argument.  
Are you saying that Unix shouldn't do it because it isn't a good thing,
or are you saying that it isn't a good thing because Unix doesn't do it?