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Re: Inconsistent quote and escape handling in substitution part of param

From: John Kearney
Subject: Re: Inconsistent quote and escape handling in substitution part of parameter expansions.
Date: Tue, 28 Feb 2012 22:28:21 +0100
User-agent: Mozilla/5.0 (X11; Linux i686; rv:10.0) Gecko/20120129 Thunderbird/10.0

On 02/28/2012 10:05 PM, Chet Ramey wrote:
> On 2/28/12 12:26 PM, John Kearney wrote:
>> But that isn't how it behaves.
>> "${test//str/"dddd"}"
>> because str is replaced with '"dddd"' as such it is treating the double
>> quotes as string literals.
>> however at the same time these literal double quotes escape/quote a
>> single quote between them.
>> As such they are treated both as literals and as quotes as such
>> inconsistently.
> I don't have a lot of time today, but I'm going to try and answer bits
> and pieces of this discussion.
> Yes, bash opens a new `quoting context' (for lack of a better term) inside
> ${}.  Posix used to require it, though after lively discussion it turned
> into "well, we said that but it's clearly not what we meant."
> There are a couple of places in the currently-published version of the
> standard, minus any corregendia, that specify this.  The description of
> ${parameter} reads, in part,
> "The matching closing brace shall be determined by counting brace levels,
> skipping over enclosed quoted strings, and command substitutions."
> The section on double quotes reads, in part:
> "Within the string of characters from an enclosed "${" to the matching
> '}', an even number of unescaped double-quotes or single-quotes, if any,
> shall occur."
> Chet

yhea but I think the point is that the current behavior is useless.
there is no case where I want a " to be printed and start a double
quoted string? and thats the current behavior.

Not so important how you treat it just need to pick 1. then you can at
least work with it. Now you have to use a temp variable.

as a side note ksh93 is pretty good, intuitive
ksh93 -c 'test=teststrtest ; echo "${test//str/"dd dd"}"'
testdd ddtest
ksh93 -c '( test=teststrtest ; echo ${test//str/"dd '\''dd"} )'
testdd 'ddtest

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