Re: ${var:+foo "$empty"}

[Chet Ramey]

Stephane Chazelas wrote:
> Hi,
>
> $ bash -c 'printf "<%s>\n" ${$:+a "$a"}'
> <a>
> $ ksh -c 'printf "<%s>\n" ${$:+a "$a"}'
> <a>
> <>
> $ dash -c 'printf "<%s>\n" ${$:+a "$a"}'
> <a>
> <>

I believe that bash is right.  Posix says explicitly that the word
on the rhs of the `+' does not undergo word splitting when it is
used.  I do not believe that Posix intended word splitting to be
performed on the result.

"$@" is the only expansion that's allowed to result in multiple
words.  And the way shells have behaved historically means that
"$@" anywhere in a word enables the `special $@ mode' handling.

Chet