From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Brown <davidb@codeaurora.org>
Subject: Re: [Q] Determing if a commit is reachable from the HEAD ?
Date: Fri, 20 Jan 2012 10:06:20 -0800
Message-ID: <20120120180620.GA8504@codeaurora.org>
References: <201201201433.30267.brian.foster@maxim-ic.com>
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Cc: Brian Foster <brian.foster@maxim-ic.com>,
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To: Andreas Schwab <schwab@linux-m68k.org>
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On Fri, Jan 20, 2012 at 03:13:58PM +0100, Andreas Schwab wrote:
> Brian Foster <brian.foster@maxim-ic.com> writes:
> 
> >  In a script, how can I determine commit Y is reachable
> >  from the current HEAD ?
> 
> test $(git merge-base HEAD Y) = $(git rev-parse Y)

Almost.  It works as long as there is only one merge base.  You really
need to check if $(git rev-parse Y) is one of $(git merge-base --all
HEAD Y)

if HEAD is a named branch, you can do

  git name-rev --refs=refs/heads/branchname Y

which will give you Y relative to branchname if it is contained within
it.

David

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