discuss: Incorrect AND / OR Precedence
Subject:
Re: Incorrect AND / OR Precedence
From:
"Ian! D. Allen" ####@####.####
Date:
9 Dec 2021 08:59:32 +0000
Message-Id: <YbHFbF/mFheXXj5q@idallen-oak.home.idallen.ca>
On Thu, Sep 16, 2021 at 10:41:49AM -0400, Bulgrien, Dennis wrote:
> Please double-check https://tldp.org/LDP/abs/html/opprecedence.html which states that && AND has higher precedence that || OR. Other web sites and my experience indicate your documentation is incorrect. In the example below, if && was executed first then echo would have to run to complete the expression prior to running false, but in actuality echo does not run because || runs first and short-circuit condition says there is no point in running echo.
>
> $ false || false && echo y
Those are "list operators", not logical operators.
From "man bash":
"Of these list operators, && and || have equal precedence"
Your example never executes the echo no matter what the precedence of
the operators is:
$ { false || false ; } && echo y
(no output)
$ false || { false && echo y ; }
(no output)
--
| Ian! D. Allen, BA, MMath - ####@####.#### - Ottawa, Ontario, Canada
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