Re: any plans for command substitution that preserves trailing newlines?

[Chet Ramey]

On 5/31/21 11:45 AM, Christoph Anton Mitterer wrote:
> Hey.
>
> I wondered whether there were any plans to implement proper support for
> command substitutions that preserves trailing newlines?

"Proper" is doing a lot of work in ths sentence.

> If that was kinda coordinated with other POSIX sh compatible shells it
> might ultimately even get standardised.

That implies it's something that people want to standardize. I haven't
seen any evidence of that.

> There seem to be a number of workarounds, using bash's read (which is
> however not portable, as the options needed aren't POSIX)

So there's already a solution that could be standardized if desired?

> or using
> sentinel values like:
>
> foo="$( command ; rc=$?; printf 'x' ; exit $rc )"
> #store rc if necessary
> ...
>
> #remove the sentinel
> foo=${foo%x}
>
> but allegedly, these have numerous issues, too, depending on which
> locales are used.

So this is a problem that people encounter infrequently, one that has a
solution that works 100% of the time in bash (your construct above plus
temporarily setting LANG=C before removing the last character), and doesn't
occur at all in the majority of situations (locales with UTF-8 encodings).

Why is inventing new syntax the right approach?

--
``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/