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Re: bin/51726: sort -n ignored if given after -k
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
> 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
>> 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 :)
Just tested on OpenBSD and FreeBSD, their sort(1) also supports -n after -k.
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