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Re: Brace expansion fail compilation


From: Florian Mayer
Subject: Re: Brace expansion fail compilation
Date: Wed, 26 Apr 2017 12:25:18 +0200

wow..., ok thanks for the quick reply

> On 26 Apr 2017, at 12:17, Pierre Gaston <address@hidden> wrote:
> 
> 
> 
>> On Wed, Apr 26, 2017 at 1:13 PM, Florian Mayer <address@hidden> wrote:
>> $ echo $BASH_VERSION
>> 4.4.12(1)-release
>> $ echo $BASH_VERSION{nobraceexpansion}
>> 4.4.12(1)-release{nobraceexpansion}
>> $ echo ${BASH_VERSION}{brace,expansion}
>> 4.4.12(1)-releasebrace 4.4.12(1)-releaseexpansion
>> $ echo $BASH_VERSION{brace,expansion}
>> => no output. Unexpected
>> $ echo $BASH_VERSIONfoo
>> => no output as expected
>> 
>> Why does
>> $ echo $BASH_VERSION{brace,expansion}
>> produce no output?
>> 
> it's because brace expansion occurs before parameter expansion
> so first
>   echo $BASH_VERSION{brace,expansion} 
> is expanded to
>   echo $BASH_VERSIONbrace $BASH_VERSIONexpansion
> and these 2 variables are not set.
> 
> you can verify with:
> $ BASH_VERSIONbrace=foo BASH_VERSIONexpansion=bar; echo 
> $BASH_VERSION{brace,expansion}
> foo bar
> 
> 
> 


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