Subject: Re: bug#30681: What characters are in [[:space:]]?

From: Paul Eggert <[email-masked]>
Date: Fri, 2 Mar 2018 14:32:06 -0800

On 03/02/2018 09:23 AM, Peng Yu wrote:
> Where is this info documented for grep?

It's not documented for grep because it's not part of grep. It's part of 
your locale.