Re: sha1 of the repo excluding history ?

From: Shawn O. Pearce <spearce@spearce.org>
Date: Apr 12, 2007, 23:40 UTC
Message-ID: <20070412234032.GE12979@spearce.org>
In-Reply-To: <f36b08ee0704121626i6a27dcecp8b0b10e0f7db2ef7@mail.gmail.com>

Yakov Lerner <iler.ml@gmail.com> wrote:

Show 9 quoted lines

>    Can I obtain from git the sha1 of the total last state of the
> repo excluding history ? This is a state that covers contents and
> names of all files and dirs, and x perm of files;
> but excludes history, timestamps, ownerhisp, and inode numbers.
> 
> That would be approximately like the slow method:
>          'find | egrep -v '/\.git(/|$)' | sort | Xcpio -o | sha1sum -'
> (imagining Xcpio that does not archive any ownership, timestamps,
> and inode numbers). Can I obtain this result immediately from git ?

	git rev-parse HEAD^{tree}

The trick here is ^{tree}; this operator takes a commit-ish (commit or tag) and returns the SHA-1 of the tree that the commit-ish points at. That SHA-1 is the SHA-1 of the file contents, names, and executable bits, but nothing else. No history.

I use it sometimes after a rebase when I reorganize history:

	old=`git rev-parse HEAD^{tree}`
	.... do rebasing magick ...
	test $old = `git rev-parse HEAD^{tree}` && echo GOOD

If I don't get back GOOD then I know I somehow changed the files in a way that isn't what I had before, and that wasn't what I wanted if all I was doing was cleaning up commit messages.

-- 
Shawn.