VMS: logicals UNIX: links, but...

[Richard A. O'Keefe]

In article <1337 at naucse.UUCP> jdc at naucse.UUCP (John Campbell) writes:
>I remember being quite surprised to discover (as I was learning unix)
>that common practice was to open full pathname entities on unix.  Instead,
>of the nice abstraction that I was used to on VMS I found references to
	^^^^^^^^^^^^^^^^
>/usr/dict/words, /usr/lib/tex/fonts, /usr/spool/uucp, etc.

If you can give me a self-contained description of the rules for
VMS version 5.0 logical name translation, taking one normal-sized piece
of paper and using a 10-point or larger font, then I will concede that
VMS has a "nice abstraction", and I shall further send you US$100.
Use any well-known functional notation: ML, Miranda, SASL, KRC, FP...
If you can do it in two pages, I'll send you $50 (I could use the clear
description that DEC didn't see fit to provide), but I won't call something
that complex a "nice abstraction".

As for the UNIX way of getting to standard files, the names have to be
stored *somewhere*.  System utilities are entitled to put information
anywhere the system designers chose to; those programs are not intended
to work with any other file, and this approach keeps those names out of
the user's "logical name" space.  Any add-on product which is sold to
people ought to come with an installation script which people can edit
to place the files in the directory of their choice.  (This makes it a
lot easier for the customers to install an upgrade and keep on running
the old version for a while.)

For another method of locating files, look at the various .*rc files.
Consider 'mail': it picks up either $MAILRC if that is defined or
$HOME/.mailrc if it is not.  In that file you can say
	DEAD=filename		# save botched messages in this file
	folder=directory	# where to save mail files
	record=filename		# save copies of outgoing messages here
amongst other things.  So you can build up a table of what files you want
the mailer to use, and say
	% MAILRC=that/file mail
You can easily set up a script to generate that file dynamically, if you
want.