NetBSD Problem Report #57670
From kre@munnari.OZ.AU Thu Oct 19 17:44:16 2023
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Message-Id: <202310191744.39JHi63f025414@jacaranda.noi.kre.to>
Date: Fri, 20 Oct 2023 00:44:06 +0700 (+07)
From: kre@munnari.OZ.AU
To: gnats-bugs@NetBSD.org
Subject: expr(1) man page contains a particularly useless example
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>Number: 57670
>Category: bin
>Synopsis: expr(1) man page contains a particularly useless example
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: bin-bug-people
>State: open
>Class: doc-bug
>Submitter-Id: net
>Arrival-Date: Thu Oct 19 17:45:00 +0000 2023
>Originator: Robert Elz
>Release: NetBSD 10.99.10
>Organization:
>Environment:
System: NetBSD jacaranda.noi.kre.to 10.99.10 NetBSD 10.99.10 (JACARANDA:1.1-20231005) #108: Fri Oct 6 03:19:02 +07 2023 kre@jacaranda.noi.kre.to:/usr/obj/testing/kernels/amd64/JACARANDA amd64
Architecture: x86_64
Machine: amd64
>Description:
In the EXAMPLES section of expr(1) the following is given as one of the
examples...
2. The following example returns zero, due to subtraction having higher
precedence than the “&” operator:
expr 1 '&' 1 - 1
That's bizarre, the precedence of the operators is irrelevant here (what it
says is correct, but pointless)
1 & (1 - 1) == 0 (1 & 0 == 0)
(1 & 1) - 1 == 0 (1 - 1 == 0)
If the man page is to have an example to illustrate that operator precedence
matters, it should be giving an example where it really does make a differemce.
Perhaps
expr 1 '|' 2 - 1
where 1 | (2 - 1) (the actual answer) == 1 (1 | 1 == 1) but
where (1 | 2) - 1 (incorrect precedence) == 2 (3 - 1 == 2).
>How-To-Repeat:
RTFM.
>Fix:
Use a better example. Or simply delete that one.
And since -10 is still in beta, perhaps pull up the fix to that,
so we don't have to go another decade or so before we have a
release containn sanity.
(Contact us)
$NetBSD: query-full-pr,v 1.47 2022/09/11 19:34:41 kim Exp $
$NetBSD: gnats_config.sh,v 1.9 2014/08/02 14:16:04 spz Exp $
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