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From: Martijn Dekker <martijn@inlv.org>
To: dash@vger.kernel.org
Subject: Re: dash: read does not ignore trailing spaces
Date: Thu, 03 Dec 2015 22:43:39 +0100	[thread overview]
Message-ID: <5660B78B.5000302@inlv.org> (raw)
In-Reply-To: <20151203211748.GC9581@chaz.gmail.com>

Stephane Chazelas schreef op 03-12-15 om 22:17:
> It's meant to split into "a" and "b", not "a", "b" and "". As
> ":" is meant to be treated as a *delimiter* or *terminator*.

That was my interpretation of the standard, too. So I reported this as a
bug to author of yash, but he reads the standard differently and came up
with a good argument for that. See:

https://osdn.jp/ticket/browse.php?group_id=3863&tid=35283#comment:3863:35283:1435293070

Summarising: POSIX states that "each occurrence in the input of an IFS
character that is not IFS white space, along with any adjacent IFS white
space, shall delimit a field". This *may* be interpreted to read that a
final non-whitespace IFS character denotes an empty final field, because
otherwise that final character wouldn't be delimiting any field, but
only terminating one. It's pretty ambiguous, though.

Based on that discussion I concluded that both interpretations are
defensible, so I didn't report this to the zsh-workers list as a bug.
(In the shell library I'm developing, which you have an earlier copy of,
I gave this quirk the id QRK_IFSFINAL instead of BUG_IFSFINAL to reflect
that it's a quirk.) Maybe this is still worth bringing up on zsh-workers
as a discussion, but lately I haven't had much time.

- Martijn


  reply	other threads:[~2015-12-03 22:13 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-02 22:37 dash: read does not ignore trailing spaces Gioele Barabucci
2015-12-02 23:25 ` Jilles Tjoelker
2015-12-03 21:02 ` Harald van Dijk
2015-12-03 21:17   ` Stephane Chazelas
2015-12-03 21:43     ` Martijn Dekker [this message]
2015-12-03 23:04       ` Stephane Chazelas
2015-12-03 23:17         ` Stephane Chazelas
2015-12-04  0:00           ` Stephane Chazelas
2015-12-03 22:26     ` Harald van Dijk
2015-12-04 19:51       ` Harald van Dijk
2016-01-29 12:57         ` Martijn Dekker
2016-06-06  8:48         ` [PATCH v2] builtin: Fix handling of trailing IFS white spaces Herbert Xu
2016-06-06 20:43           ` Harald van Dijk
2016-06-07  9:25             ` [PATCH v3] " Herbert Xu
2016-06-12 10:35               ` Harald van Dijk
2016-06-12 11:06                 ` Herbert Xu
2016-06-12 11:12                   ` Harald van Dijk
2016-06-12 12:17                     ` [PATCH v4] " Herbert Xu
2016-06-19 22:01                       ` Harald van Dijk
2016-06-20  1:28                         ` Herbert Xu

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