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bug#22216: test, expr Operator Precedence and Associativity
From: |
Eric Blake |
Subject: |
bug#22216: test, expr Operator Precedence and Associativity |
Date: |
Mon, 21 Dec 2015 17:05:09 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 12/21/2015 05:00 PM, 積丹尼 Dan Jacobson wrote:
> OK. Also make sure (info "(coreutils) test invocation") makes it clear that
> one cannot use
> test -f $1 -a $1 ! -ot $2 #and must use
> test -f $1 -a ! $1 -ot $2 #.
Use of -a in test is inherently non-portable. POSIX even says so -
there are some expressions which are completely ambiguous when you
attempt to use -a or -o.
Also, your lack of quoting is a classic pitfall for how to incorrectly
use test.
Better than what you typed would be using:
test -f "$1" && test ! "$1" -ot "$2"
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- bug#22216: test, expr Operator Precedence and Associativity, Dan Jacobson, 2015/12/21
- bug#22216: test, expr Operator Precedence and Associativity, Pádraig Brady, 2015/12/21
- bug#22216: test, expr Operator Precedence and Associativity, 積丹尼 Dan Jacobson, 2015/12/21
- bug#22216: test, expr Operator Precedence and Associativity,
Eric Blake <=
- bug#22216: test, expr Operator Precedence and Associativity, 積丹尼 Dan Jacobson, 2015/12/21
- bug#22216: test, expr Operator Precedence and Associativity, 積丹尼 Dan Jacobson, 2015/12/21