+++ /dev/null
-Date: Sat, 13 Aug 2005 22:16:02 -0700 (PDT)
-From: Linus Torvalds <torvalds@osdl.org>
-To: Steve French <smfrench@austin.rr.com>
-cc: git@vger.kernel.org
-Subject: Re: sending changesets from the middle of a git tree
-Abstract: In this article, Linus demonstrates how a broken commit
- in a sequence of commits can be removed by rewinding the head and
- reapplying selected changes.
-
-On Sat, 13 Aug 2005, Linus Torvalds wrote:
-
-> That's correct. Same things apply: you can move a patch over, and create a
-> new one with a modified comment, but basically the _old_ commit will be
-> immutable.
-
-Let me clarify.
-
-You can entirely _drop_ old branches, so commits may be immutable, but
-nothing forces you to keep them. Of course, when you drop a commit, you'll
-always end up dropping all the commits that depended on it, and if you
-actually got somebody else to pull that commit you can't drop it from
-_their_ repository, but undoing things is not impossible.
-
-For example, let's say that you've made a mess of things: you've committed
-three commits "old->a->b->c", and you notice that "a" was broken, but you
-want to save "b" and "c". What you can do is
-
- # Create a branch "broken" that is the current code
- # for reference
- git branch broken
-
- # Reset the main branch to three parents back: this
- # effectively undoes the three top commits
- git reset HEAD^^^
- git checkout -f
-
- # Check the result visually to make sure you know what's
- # going on
- gitk --all
-
- # Re-apply the two top ones from "broken"
- #
- # First "parent of broken" (aka b):
- git-diff-tree -p broken^ | git-apply --index
- git commit --reedit=broken^
-
- # Then "top of broken" (aka c):
- git-diff-tree -p broken | git-apply --index
- git commit --reedit=broken
-
-and you've now re-applied (and possibly edited the comments) the two
-commits b/c, and commit "a" is basically gone (it still exists in the
-"broken" branch, of course).
-
-Finally, check out the end result again:
-
- # Look at the new commit history
- gitk --all
-
-to see that everything looks sensible.
-
-And then, you can just remove the broken branch if you decide you really
-don't want it:
-
- # remove 'broken' branch
- git branch -d broken
-
- # Prune old objects if you're really really sure
- git prune
-
-And yeah, I'm sure there are other ways of doing this. And as usual, the
-above is totally untested, and I just wrote it down in this email, so if
-I've done something wrong, you'll have to figure it out on your own ;)
-
- Linus
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