Re: bin/51726: sort -n ignored if given after -k

[Abhinav Upadhyay <er.abhinav.upadhyay%gmail.com@localhost>]

The following reply was made to PR bin/51726; it has been noted by GNATS.

From: Abhinav Upadhyay <er.abhinav.upadhyay%gmail.com@localhost>
To: NetBSD GNATS <gnats-bugs%netbsd.org@localhost>
Cc: abhinav%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
	David Brownlee <abs%absd.org@localhost>
Subject: Re: bin/51726: sort -n ignored if given after -k
Date: Tue, 20 Dec 2016 21:30:14 +0530

 On Sun, Dec 18, 2016 at 9:54 PM, Abhinav Upadhyay
 <er.abhinav.upadhyay%gmail.com@localhost> wrote:
 > On Sun, Dec 18, 2016 at 1:55 PM, Robert Elz <kre%munnari.oz.au@localhost> wrote:
 >> The following reply was made to PR bin/51726; it has been noted by GNATS.
 >>
 >> From: Robert Elz <kre%munnari.OZ.AU@localhost>
 >> To: gnats-bugs%NetBSD.org@localhost
 >> Cc:
 >> Subject: Re: bin/51726: sort -n ignored if given after -k
 >> Date: Sun, 18 Dec 2016 15:23:38 +0700
 >>
 >>      Date:        Sun, 18 Dec 2016 02:05:01 +0000 (UTC)
 >>      From:        David Holland <dholland-bugs%netbsd.org@localhost>
 >>      Message-ID:  <20161218020501.468347A302%mollari.NetBSD.org@localhost>
 >>
 >>    |  If you're using -k you're supposed to put the key flags in the -k
 >>    |  argument, that is, sort -k 3nr.
 >>
 >>  Not quite, using global options is still fine, they're just not
 >>  supposed to apply to a key specified if that key has any sort selections
 >>  of its own.
 >>
 >>  Our sort doesn't do that, it merges global options and key specific
 >>  options, in a kind of weird way --- but the behaviour described (while
 >>  perhaps not strictly correct) is I think what is intended.
 >>
 >>  That is, when sorting a key field, you get whatever sort options are
 >>  specified for that key, merged with whatever global options had already
 >>  been given - later global options are supposed to affect the next key
 >>  (or the backup default sort if the keys are equal).   That is, that's how
 >>  the NetBSD sort is written.
 >>
 >>    |  Technically I think if you write -k 3 -n -r and it doesn't honor the
 >>    |  -n it's doing what you asked.
 >>
 >>  According to our sort's design, yes, though I don't think that is posix.
 >>
 >>    | And I think if you write -k 3 -n -r and
 >>    | it *does* sort in reverse order, then *that*'s a bug. sigh.
 >>
 >>  Yes, probably.
 >>
 >>    |  sort's argument handling is a trainwreck.
 >>
 >>  That mild?
 >>
 >>    |  And thus the code in sort that deals with it is horrifying.
 >>
 >>  Yes.   We could probably simplify it a lot if we made it posix
 >>  conformat (where any key specific ordering options disable all
 >>  the globals for that key) but it has been as it is for a long time
 >>  now (mayve even, modulo the k stuff) has been like it since 6th or
 >>  7th edition unix.   So changing it might break a lot - who knows?
 >
 > I have been going over the sort(1) man page from posix, and at one
 > place (in the APPLICATION USAGE section) it says the following about
 > the use of ordering options after -k:
 >
 > "The wording in the OPTIONS section clarifies that the -b, -d, -f, -i,
 > -n, and -r options have to come before the first sort key specified if
 > they are intended to apply to all specified keys. The way it is
 > described in this volume of POSIX.1-2008 matches historical practice,
 > not historical documentation. The results are unspecified if these
 > options are specified after a -k option."
 >
 > So, I guess using `sort -k3 -n -r` is undefined behavior?. That said,
 > the example mentioned in the PR (sort -k 2 -n -r) does work with GNU
 > sort(1). I had a patch ready yesterday, so just posting it here :)
 >
 > This patch lets sort(1) associate -b, -d, -f, -i, -n, -r options to
 > specific fields if specified after -k.  All ATF tests for sort(1) are
 > passing except for a couple of cases in kflag_alpha, but they look
 > ambiguous to me and one of the similar tests is commented out as
 > broken. If we want to accept this behavior in our sort(1) and the
 > patch looks in the right direction, I will try to dig in and get those
 > test cases passing  :)
 >
 > http://www.netbsd.org/~abhinav/sort.c.diff
 
 Just tested on OpenBSD and FreeBSD, their sort(1) also supports -n after -k.
 
 -
 Abhinav