VMS: logicals UNIX: links, but...

Paul Houtz gph at hpsemc.HP.COM
Mon Apr 17 05:22:02 AEST 1989


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

> And what on earth do you think the logical names SYS$INPUT, SYS$OUTPUT,
>and so on are in VMS?  The VAX-11 C compiler thinks they are stdin, stdout,

Wrong.  Wrong.  Wrong.   The names are similar.  Some of the functionality
is similar.  But they are NOT stdout and stdin.  Not unless the functionality
is identical.  You see, Unix stdou and stdin are used a lot by programmers
because there is a REASON.  You can use them in pipes and you can easily
redirect them.   There is no such reason on VMS.  So they sound the
same, but they aint.

> UNIX has no aliases.  There is *NO* kernel support for aliases whatsoever.
> They are a feature of the C shell.  I write Bourne shell scripts.  If you
> call a program using exec(), you do not see aliases.

The first time I heard this, I made me mad.  I mean, who after all, uses
Unix and uses only the bourne shell and never uses an ALIAS.  Seemed like
a pretty stupid argument.  

But then, I realized,  you are absolutely right.  The place for aliases 
and logicals is not in UNIX, but in the shell.   Probably what will happen
is a new shell will eventually appear that will have this functionaly 
which UNIX does NOT have, and that will solve the problem.


>Let me make my position perfectly plain.
>(1) Every operating system should provide some means whereby the caller
>    of a program may provide an association between tokens used by a
>    program and actual files which those tokens are to refer to.
>	***UNIX DOES THIS***

Of course Unix doesn't do this.  It does some of this, but not all.  
Example:  I recently ported a cobol system written in a latin american
country that ran 10 jobs sequentially and they all wrote to PRINTER-LISTADO.
It was a benchmark, so I was not allowed to change source.  I could not use 
ln because that would overlay the results each time.   So I had to 
write a script to mv the PRINTER-LISTADO file to some other file at the
end of each job.  It seems and is trivial, but it an example of how incomplete
the unix "logical" functionality is (in my opinion).

Anyway, your note is very enlightening.  I appreciate the information you 
have provided.   It is unfortunate that this notes string generates at 
least as much heat as light.   I admit that I contributed some of the heat
as well.



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