Re: [PATCH] printf: add %#s alias to %b

[Pádraig Brady]

On 07/09/2023 19:46, Eric Blake wrote:
> On Thu, Sep 07, 2023 at 11:53:54PM +0700, Robert Elz wrote:
> > And for those who have been following this issue, the new text for
> > the forthcoming POSIX version has removed any mention of obsoleting
> > %b from printf(1) - instead it will simply note that there is will be
> > a difference between printf(1) and printf(3) once the latter gets its
> > version of %b specified (in C23, and in POSIX, in the next major version
> > that follows the coming one, almost certainly) - and to encourage
> > implementors to consider possible solutions.
> >
> > I've considered, and I don't see a problem needing solving, so I'm
> > intending to do precisely nothing, unless someone actually finds a
> > need for binary output from printf(1), which seems unlikely to
> > ever happen to me (I mean a real need, not just to be the same as printf(3)
> > "just because").
> >
> > So, we can all go back to sleep now - and Chet, I'd undo $#s before it
> > appears in a release, there's no need, and having it might eventually
> > just cause more backward compat issues.
>
> Indeed, at this point, even though I proposed a patch for %#s in
> coreutils, I'm inclined to NOT apply it there.

Agreed.

> The ksh extension of %..2d to output in binary does sound worth
> replicating; I wonder if glibc would consider putting that in their
> printf(3); and I could see adding it to Coreutils (whether or not bash
> adds it - because ksh already has it).

This does seem useful as there is prior art, and it's quite general.
FWIW there is related functionality in coreutils currently through `basenc 
--base2msbf`

cheers,
Pádraig