"Geoff Russell" <geoffrey.russell@xxxxxxxxx> writes:
> This should be simple! I have a series of commits:
>
> 1---2---3---4---5
>
> I want to go back to 3 but not branch, so I want
>
> 1---2---3---4---5---3
>
> ?
>
> git checkout 3...
>
> gets me the commit on a detached head, but I don't know how to put this back
> as the HEAD.
Lets check what git does in each of scenarios. Let's assume that
current branch is named 'master'.
At beginning we have:
1---2---3---4---5 <--- master <--- HEAD
HEAD contents is "ref: refs/heads/master"
1. Now, "git checkout 3...", which is equivalent to "git checkout 3",
detaches HEAD because commit '3' is not a head (is not a branch), so
we have:
1---2---3---4---5 <--- master
^
\
\-------------- HEAD
HEAD contents is "<sha1 of 3>"
2. If we did "git reset --hard 3" we would rewind the history,
resulting in the following situation:
1---2---3 <--- master <--- HEAD
\
\-4---5 <... master@{1}, ORIG_HEAD, HEAD@{1}
and now commits 4 and 5 are referenced only by reflogs, and by the
(temporary) "last position of HEAD" reference named ORIG_HEAD.
3. Now, if you have published 1..5 history you would not want
(usually) to rewind published branch. If you do the following:
$ git revert --no-commit 5
$ git revert 4
you would get the following:
1---2---3---4---5---(5^-1 4^-1 => 3) <--- master <--- HEAD
git-revert applies reversal of changes in given commit, in the
"patch -R" ("patch --reverse") sense. Using '--no-commit' option
allows to squash reverting two commits into one commit. The ordering
of reverting ensures that there are no merge conflicts.
4. Or you can just put the _contents_ of revision 3 into your working
tree, either using plumbing command git-read-tree, or by checking out
or resetting to top tree: "git checkout 3^{tree}", or
"git checkout 3 -- .", or equivalent git-reset invocation.
This way you would get exactly
1---2---3---4---5---3 <--- master <--- HEAD
but the relation of 5---3 parentage is unclear: you would have to
explain it in the commit mesage.
HTH
--
Jakub Narebski
Poland
ShadeHawk on #git
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