Re: manpage: Potentially missing right curly brace

[Paul Eggert]

On 12/29/20 7:43 PM, Jim Meyering wrote:
> On Tue, Dec 29, 2020 at 6:03 AM Marek Suppa <mr@shu.io> wrote:
> > While reviewing the way basic regular expressions are implemented in
> > grep, I noticed that the section where they are described in the man
> > page is missing the right curly brace. Unless I missed anything, this is
> > probably unintended, as the right curly brace is already mentioned
> > multiple time in the manpage as well....
>
> Thank you for the patch. I have applied it (with minor commit-log
> wording changes) and pushed here:
> https://git.savannah.gnu.org/cgit/grep.git/commit/?id=181f1647f7250d3a7c104bf1d7ce4a3fafa19e3b

Unfortunately this is not quite right, as "}" is not a special character 
in POSIX regular expressions. For BREs, POSIX says that "grep '}'" has 
well-defined behavior (it matches lines with closing braces) and that 
the interpretation of "grep '\}'" is undefined. The situation with EREs 
("grep -E") is similar.

Marek had a point that the grep documentation was not properly saying 
that BRE interval expressions need backslashes before both { and }. So I 
installed the attached patch, which attempts to fix that problem, while 
also being more precise about which characters are special and which 
(like "}") are not.

0001-doc-clarify-special-chars-and.patch
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