List,
Could anyone explain how the git commit ID will include all the files that devloper makes changes on?
How git commit ID works?
Thanks for any help!
---henry
threads / discuss / 32022
how the commit ID come from in GIT?
Subject: how the commit ID come from in GIT?
Re: how the commit ID come from in GIT?
On Monday, November 05, 2012 at 15:04 EST,
hong zhang <henryzhang62@yahoo.com> wrote:> Could anyone explain how the git commit ID will include all the files > that devloper makes changes on? > > How git commit ID works?
In short, a Git commit points to a tree object that describes the full state of the source tree plus metadata like the commit author, date, description, and a pointer to the commit object(s) that preceded the commit. The commit id itself is the SHA-1 of the contents of the commit object. Any change of the source tree will affect the top-level tree object's SHA-1 which in turn affects the SHA-1 of the commit. Also, because a commit contains the timestamp of the commit object's creation even two commits that are content-wise identical will have different SHA-1s.
If you haven't read it, the Pro Git books explains Git's object model in detail: http://git-scm.com/book/en/Git-Internals-Git-Objects
That description is quite detailed, and most users don't need to go that deep.
-- Magnus Bäck baeck@google.com
Re: how the commit ID come from in GIT?
On Mon, Nov 05, 2012 at 12:04:06PM -0800, hong zhang wrote:
> Could anyone explain how the git commit ID will include all the files > that devloper makes changes on? > > How git commit ID works?
To expand on the answer provided by Magnus, I would also suggest reading the classic "Git from the bottom up" document [1], and if you want a totally informal and fun introduction to how these cryptographic hashes come about and why they are useful, I suggest reading "The Git Parable" [2].
1. http://newartisans.com/2008/04/git-from-the-bottom-up/ 2. http://tom.preston-werner.com/2009/05/19/the-git-parable.html