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Re: [Help-bash] Question about escaping in backquote string in double qu

From: Chet Ramey
Subject: Re: [Help-bash] Question about escaping in backquote string in double quoted strings
Date: Tue, 14 May 2019 13:55:18 -0400
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.1

On 5/2/19 2:52 PM, Andy Chu wrote:
> On Thu, May 2, 2019 at 10:56 AM Greg Wooledge <address@hidden> wrote:
>> On Fri, May 03, 2019 at 01:05:47AM +0800, KHMan wrote:
>>> echo "[` echo \" \\" \" `]"             # [ " ]      (A)
>>> So my question is, what did bash do in (A), which seems to affect the
>>> specific case of the double quote char only?
>> At this point you either run away screaming, or you just admit that
>> everyone was *correct* when they told you that you should use $(...)
>> instead of `...` because backslash handling inside `...` is too surprising.
> Yeah I would agree to just use $() and get on with life.  It's accepted
> everywhere, so you can safely modify existing shell scripts to use $()
> instead of `` whenever there's an issue.

This is the best choice without a doubt.

> I implemented part of the surprising behavior of \" inside `` for OSH
> recently, because virtualenv depended on it.  I was not able to come up
> with any rule that didn't involve special cases for a specific number of
> backslashes.  

The real difference is whether or not the command substitution occurs
within double quotes.

``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    address@hidden

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