On Sat, Aug 01, 2020 at 06:59:43PM +0200, Klemens Nanni wrote:
> On Sat, Aug 01, 2020 at 05:40:07PM +0100, Jason McIntyre wrote:
> > i'm worried that you're blurring the distinction between asynchronous
> > and co-process for the reader. i think that's relevant because, as you
> > say, a page like sh(1) does not document co-processes, whereas ksh(1)
> > does.
> You raise a valid point.
>
> > as i understand it, ksh explains co-processes as a type of asynchronous
> > process. and the setting of "!" is applicable to both. is that right?
> Correct. Both background jobs (`&') and co-processes (`|&') are
> asynchronous and co-processes are background jobs by definition.
>
> What makes co-processes different is a two-way pipe between them and
> the shell, i.e. you can read and write in both directions.
>
> > so could your text be better written as:
> >
> > Process ID of the last background or asynchronous process started.
> > If no processes have been started, the parameter is not set.
> >
> > this would catch the setting of "!" for both async and co-process,
> > without making the text read like the two are identical.
> >
> > if your concern is that you need to be able to /co-process, then i'd
> > rewrite the text to not blur the two:
> >
> > Process ID of the last background, co-process, or asynchronous
> > process started.
> >
> > but i dislike that, because it means the text suffers because of an
> > arbitrary request to make a specific search work.
> Indeed, I'd like to have `/co-process<enter>' show it.
>
> > i guess we could add a note to the "Some notes concerning co-processes"
> > section if it needs more clarity.
> I don't think this is needed.
>
> Background jobs as well as co-processes are async and background jobs or
> rather `&' is documented as "asynchronous command" in other places of
> the manual, so how about this?
>
hmm. so then the current text ("the last background process") already
covers all these cases. why single out co-processes?
for the reader, i think the idea of background is easier to understand
as an umberella term, rather than asynchronous, even if it's maybe not
so correct.
either you or i have trimmed your original mail, explaining why
this was important ;)
jmc
>
> Index: ksh.1
> ===================================================================
> RCS file: /cvs/src/bin/ksh/ksh.1,v
> retrieving revision 1.209
> diff -u -p -r1.209 ksh.1
> --- ksh.1 7 Jul 2020 10:33:58 -0000 1.209
> +++ ksh.1 1 Aug 2020 16:59:10 -0000
> @@ -1247,8 +1247,8 @@ The following special parameters are imp
> set directly using assignments:
> .Bl -tag -width "1 ... 9"
> .It Ev \&!
> -Process ID of the last background process started.
> -If no background processes have been started, the parameter is not set.
> +Process ID of the last background process or co-process started.
> +If no asynchronous processes have been started, the parameter is not set.
> .It Ev \&#
> The number of positional parameters ($1, $2, etc.).
> .It Ev \&$
>
