Re: Substring Expansion doesn't respect IFS when using in Heredoc

[Chet Ramey]

On 9/1/22 12:54 PM, Aloxaf Yin wrote:
> Hello, I encountered something strange when using bash. It seems like a bug
> so someone suggested that I ask here.
>
> Here is the test code.
>      declare -a arr=(12 34 56 78 90)
>
>      IFS=','
>
>      cat <<<"${arr[*]:0}"
>
>      cat <<EOF
>      ${arr[*]:0}
>      ${arr[*]}
>      EOF
>
> The result is as follows. As you can see the comma is missing from the
> second line.
>
>      12,34,56,78,90
>      12 34 56 78 90
>      12,34,56,78,90

It does seem strange. Here-document bodies don't undergo word splitting, so
the expansion of $* and ${arr[@]} should separate the words with the first
character of $IFS. The current bash behavior is compatible with ksh93, but
the behavior has varied between versions.

I'll look at it after bash-5.2 is released.

Chet

--
``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/