Re: [libgpiod][PATCH] tools: gpiomon: add timeout option

[Kent Gibson <warthog618@xxxxxxxxx>]

On Tue, May 30, 2023 at 02:21:18PM +0300, andy.shevchenko@xxxxxxxxx wrote:
> Tue, May 30, 2023 at 05:29:23PM +0800, Kent Gibson kirjoitti:
> > On Mon, May 29, 2023 at 08:20:44PM +0000, Gabriel Matni wrote:
> > > From: Gabriel Matni <gabriel.matni@xxxxxxxx>
> 
> ...
> 
> > My preferred solution is to run gpiomon as a coproc and have the
> > controlling script perform the timeout. e.g.
> > 
> > #!/bin/env bash
> 
> Oh, this is too bad.
> 
> > coproc gpiomon "$@"
> > while :
> > do
> >         read -t5 -u ${COPROC[0]} event || break
> >         echo $event
> > done
> > kill $COPROC_PID
> 
> I'm wondering what coproc is and why it requires bash.
> 

And I'm wondering why your mail got to the list, but not to me directly,
despite being directly addressed.  It isn't even in my junk folder.
And it was gmail to gmail.  Now that is weird.

Anyway, coproc is a feature of many shells, such as bash, zsh, ksh.
I don't think or ash or dash have coproc, but then you cn always use named
pipes to similar effect.  It would be similar to the simple gpioset
daemon I posted the other day, just in reverse.

I did say that coproc was my preferred solution, not that it is the only
one. 

> What I want to have and keep that working is that all our tools can be run in
> Busybox environment (embedded application). That's why I'm against seeing bash
> in any form of the tooling.
> 

It isn't IN the tooling.  It is in the shell that calls the tooling.
The tool test suite does require bash, but that is due to the framework we
use, not coproc.

I take it you would be in favour of an idle timeout option then?

I'm puzzled why no one has ever asked for it before, if it is something
that is in demand.

Cheers,
Kent.