[PATCH] Add some simple howtos, culled from the mailing list.

I think these are useful, and I think putting them in a new "howto"
directory might help some users until we get to the point of splitting
up the tutorial to be easier to read.

Given the authorship, I think it's safe to put these in the repository.

Signed-off-by: Ryan Anderson <ryan@michonline.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/Documentation/howto/rebase-and-edit.txt b/Documentation/howto/rebase-and-edit.txt
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+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
+
+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
+	rm .git/refs/heads/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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