Re: [PATCH 1/4] run-command: add new check_command helper

> > But if we know from reading waitpid(3) that waitpid should only fail due
> > to EINTR, or due to bogus arguments (e.g., a pid that does not exist or
> > has already been reaped), then maybe something like this makes sense:
> >
> >   while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
> >           ; /* nothing */
> 
> But we don't want to wait synchronously here, we just want to ping.

> > After the fix above, yes; in the original we would always have exited
> > already.
> 
> No:
> 
> +       if (waiting != cmd->pid)
> +               return 1;
> 
> If waiting < 0, waiting != cmd->pid, and therefore this return is not
> triggered, and there's only one more return at the end of the
> function.