Re: ${b+s ''}

[Chet Ramey]

On 2/16/19 11:38 AM, sunnycemetery@gmail.com wrote:
> I would like to include a null string as part of a parameter expansion word:
> 
>> mapfile -t${bNullDelimited+d ''}
> 
> When bNullDelimited is set, I expect this to expand to:
> 
>> mapfile -td ''
> 
> However, it expands to:
> 
>> mapfile -td

There are mixed behaviors. The idea behind the bash behavior is that a
null string added to a non-empty word is simply discarded, and this happens
while the word after the `+' is being processed, before word splitting.

bash/ksh93/zsh do it one way, ash-derived shells/mksh/yash do it another.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/