From mboxrd@z Thu Jan  1 00:00:00 1970
From: John Keeping <john@keeping.me.uk>
Subject: Re: [BUG] Documentation: git log: --exit-code undocumented?
Date: Tue, 2 Dec 2014 12:27:05 +0000
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Cc: Junio C Hamano <gitster@pobox.com>, David Kastrup <dak@gnu.org>,
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To: Sergey Organov <sorganov@gmail.com>
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On Tue, Dec 02, 2014 at 02:30:31PM +0300, Sergey Organov wrote:
> Junio C Hamano <gitster@pobox.com> writes:
> 
> > David Kastrup <dak@gnu.org> writes:
> >
> >> I disagree that --exit-code does nothing: it indicates whether the
> >> listed log is empty.  So for example
> >>
> >> git log -1 --exit-code a..b > /dev/null
> >>
> >> can be used to figure out whether "a" is a proper ancestor of "b" or
> >> not.
> >
> > Hmph.
> >
> >     $ git log --exit-code master..maint >/dev/null; echo $?
> >     0
> >     $ git log --exit-code maint..master >/dev/null; echo $?
> >     1
> >
> > That is a strange way to use --exit-code.
> 
> What's the best way then to tell if "a" is an ancestor of "b"?

git merge-base --is-ancestor a b