shell pipeline to reverse the order of lines.

[John F Haugh II]

In article <2775 at kraftbus.cs.tu-berlin.de> net at opal.cs.tu-berlin.de (Oliver Laumann) writes:
>A vendor is free to put a version of `ls' on their UNIX port that
>doesn't support the -l option any longer.  Does this make `ls -l'
>non-standard?  Certainly not.

Name one that has done so.  This is a straw man argument.  No vendor
would ever remove the 'ls' command simply because removing it would
remove a significant part of what UNIX is.  However, the issue of
which options are ``standard'' in the 'tail' command is far more
clear - those options which the most common subset of implementations
contain.

As I pointed out from the Release 5.0 UNIX System User's Manual, the
`-r' option was not a ``common'' feature in System V UNIX.  This manual
predates 4.3BSD many several years.  System V UNIX is the most common
UNIX running on i286 and i386 systems, which are themselves the most
common PC platforms running UNIX.  And in the one-up category, I know
that 'tail' was present in the USG 3.0 and 4.0 releases for the PDP-11
since I used it when tailing logs from kernel builds.

>The fact that it may not exist on *all* systems is irrelevant.  I'm sure
>that for almost any UNIX command (except maybe date, ls, etc.) you will
>be able to find a system where this command does not exist.

No, but the fact that it does not exist on =most= systems is relevant.
The tail command exists on every single UNIX system I've ever used, and
that numbers over a dozen.  But the '-r' option exists where?  [ Yeah, I'm
a System V bigot, so don't point out that it exists in BSD land ... ]

>> As for being a ``BSD'' feature, I've yet to see a UNIX system without
>> the command,
>
>Why do you think `tail' is under /usr/ucb (on those systems that have
>a /usr/ucb)?  If the commands under /usr/ucb are not BSD commands,
>then what *is* a BSD command?

How about ... it's there because it contains BSD-only features?  Is it
possible that -r is a BSD-only feature and they put the command there
because of that?

If tail is a BSD-only command why isn't the source part of the freed
BSD source code?  It isn't.  I'm certain someone with a V7 manual
(mine has left my possession years ago) will verify my statement that
it was a part of 7th Edition or System III at the least.  I do seem
to recall seeing tail used in examples given in documents written about
the time of V7 (which predates all the 4BSD releases ...)

I was going to get my German/English dictionary out and try to explain
it to you in German, but your English seems good enough.  What part of
"-r isn't a standard feature" don't you understand exactly?
-- 
John F. Haugh II        | Distribution to  | UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832 | GEnie PROHIBITED :-) |  Domain: jfh at rpp386.cactus.org
"I've never written a device driver, but I have written a device driver manual"
                -- Robert Hartman, IDE Corp.