Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!ames!hc!beta!unm-la!unmvax!nmtsun!hydrovax
From: hydrovax@nmtsun.nmt.edu (M. Warner Losh)
Newsgroups: comp.os.misc
Subject: Re: OS features
Summary: A brief explination and a pointer
Message-ID: <1169@nmtsun.nmt.edu>
Date: 14 Dec 87 19:55:22 GMT
References: <1971@cup.portal.com>
Organization: NMT Hydrology program
Lines: 55

In article <1971@cup.portal.com>, Mark_G_Woodruff@cup.portal.com writes:
[[ Mark is summarizing responces that he got and asks for some elaberation.]]

>   >  Command completion   (The DEC OS's get this better than Unix)
>      [Could you please elaborate?]
>   >  Tops-20:  the COMND jsys -- completion and help in every command.
>      [Please explain.]
Command completion:
This is a simple concept.  When the user has typed in enough of the command
to make it unique and hits a specified key (usually ESCAPE in TOPS-20), the
rest of the command appears "by magic".  This may be difficult to understand
from a unix point of view, since all of the commands are cryptic beyond
believe (they can be learned, but it is painful).  In contrast the TOPS-20
and VMS commands are long and verbose, allowing you to know EXACTLY (or
nearly so) what is going down.  For example, on TOPS-20, to print a file
you type
@ PRint (file) Foo.txt /Copies:2
Where the uppercase letters denote what the user typed, then hit esacpe
to complete rest of the command.  The stuff in parens are noice words
that allow the user a quick mneumonic reference.  These words aren't
stictly needed.  I'm not exacltly sure about the number of letters in
this command, but they are close.  Now, you say, this is really stupid 
that I need to type an escape key many times for each command.  You don't
have to, as the EXEC on TOPS-20 will alos accept:
@ PR FOO.TXT/C:2
@ PRIN FOO.TXT/COP:2
etc.
You needn't use the command completion, but it was there if you got
stuck.  Very useful for learning the system.

>   >  Most important feature: coherent design
An obvious plug for VMS...... :-)
>   >  VMS/AmigaDOS symbolic names.
>      [Please explain.]
Symbolic name, also called logical names are in a way similar to
environmental variables in UNIX.  They differ in that they can be
used as file names (that is the OPERATING SYSTEM understands them
as such) in any contect where a file name would occure.  They have
the advantage that you can write code like:
	fopen ("SPOOL_DIR:tmp", "w");
and have SPOOL_DIR point to something useful.  This means that you
need not recompile your program to move the spooler directory.  You
can also change this, in certain cased, WHILE THE PROGRAM is running.
From what I have seen, it appears that the symbolic names (which
I read as logical names.  Somebody correct me if I'm wrong) to 
be a superset of enviornment symbols.

			Warner Losh
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