bug#23451: 25.0.93; Clarify the dependency on find/grep for platforms not having those tools

[npostavs]

Dmitry Gutov <dgutov@yandex.ru> writes:

> On 5/29/17 5:58 AM, npostavs@users.sourceforge.net wrote:
>
>> So when <cmd> is grep, and the number of files is greater than the
>> command line length limit, the exit status is effectively random (it
>> depends on 'find' decides to group the batches of files it passes to
>> 'grep').
>
> Can we make Grep exit with 0 no matter if it matched something or not?
> So that non-zero means an actual problem.
>
> There is no suitable command-line option, it seems, but maybe there's
> a shell-based option? Like 'grep ... || exit 0', but I don't think we
> want to swallow exit statuses higher than 1.

This seems to work:

    find ... -exec sh -c 'grep -i -E -nH -e turn-on-eldoc-mode "$@" ; [ $? -le 
1 ]' sh '{}' +