Thank you for your detailed explanation.
My understanding of this matter is at a different level with your help.
I wonder why this command doesn't work well.
I intend to find the comment with the keyword "12" but without "comments"
whereas the output is something like this:
git log --perl-regexp --all-match --grep=12 --grep '\b(?!comments\b)\w+'
commit f5b6c3e33bd2559d6976b1d589071a5928992601
Author: sunshilong <sunshilong369@xxxxxxxxx>
Date: 2020-04-12 23:00:29 +0800
comments 2020.04.12 ng
Thank you for your attention to this matter.
On Thu, Jul 16, 2020 at 11:32 PM Jeff King <peff@xxxxxxxx> wrote:
>
> On Sat, Jul 11, 2020 at 01:48:04PM +0800, 孙世龙 sunshilong wrote:
>
> > Thank you for taking the time to respond to me.
> >
> > When I run the said shell command, this error reported:
> > # git log -P --all-match --grep '12' --grep '\b(?!t123\b)\w+'
> > fatal: unrecognized argument: -P
> >
> > The version of git which I am currently using is 2.7.4.
>
> Try replacing "-P" with "--perl-regexp"; the shorter name was added in
> v2.14.0. You'll also need a version of Git built with libpcre support.
> If it's not, you'll get a message like:
>
> $ git log --perl-regexp --all-match --grep=12 --grep '\b(?!t123\b)\w+'
> fatal: cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE
>
> > One more question, could you please explain '\b(?!t123\b)\w+' in
> > more detail for me?
> > Or suggest some related documents for me to go through?
>
> The (?!...) block is a negative lookahead assertion in perl-compatible
> regular expressions. So it's looking for a word boundary (\b) _not_
> followed by t123.
>
> I'm not sure if that solves your original problem, though. It won't
> match "t123", but presumably there are other words in that commit
> message.
>
> A negative lookbehind like:
>
> git log --perl-regexp --grep='(?<!t)12'
>
> might work, if the distinction between "b12" and "t123" is important. Or
> if you care about "12" but not "123", then maybe just asking for a word
> boundary at the end would work:
>
> --grep='12\b'
>
> -Peff
