Subject: bug#20728: 25.0.50; grep and grep-find templates should have a place holder for the --color argument

From: Eli Zaretskii <[email-masked]>
Date: Sun, 28 Jun 2015 17:35:32 +0300

> Cc: [email-masked]
> From: Dmitry Gutov <[email-masked]>
> Date: Sun, 28 Jun 2015 11:05:52 +0300
> 
> On 06/28/2015 05:42 AM, Eli Zaretskii wrote:
> 
> > Isn't it the other way around: Windows wants 'always' (except when it
> > doesn't, see below), while others want 'auto'?
> 
> When will `always' not work for the others?

I answered that below:

> > As to when you won't want 'always': it's when Grep is invoked as part
> > pf a pipeline, where it's not the last part, or when the Lisp program
> > that invokes it wants to interpret the results, as opposed to showing
> > them to the user.

> I'd want `nil' in that case, right?

In which case?  And what do you mean by 'nil' in this context?  We are
talking about the value of the --color= Grep option, don't we?

> And I'd have to specify it explicitly anyway, if I want
> compatibility with Windows.

You lost me.

> So, why do we use `auto'?

My guess would be: because it mostly does what we want, AUTOmatically:
it produces SGR color sequences when Grep is run as a subprocess via a
pty, and does not produce them when Grep's output is a pipe.