NAME¶

git-rebase - Forward-port local commits to the updated upstream head

SYNOPSIS¶

git rebase [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
        [<upstream> [<branch>]]
git rebase [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
        --root [<branch>]
git rebase --continue | --skip | --abort | --edit-todo

DESCRIPTION¶

If <branch> is specified, git rebase will perform an automatic git checkout <branch> before doing anything else. Otherwise it remains on the current branch. If <upstream> is not specified, the upstream configured in branch.<name>.remote and branch.<name>.merge options will be used; see git-config(1) for details. If you are currently not on any branch or if the current branch does not have a configured upstream, the rebase will abort. All changes made by commits in the current branch but that are not in <upstream> are saved to a temporary area. This is the same set of commits that would be shown by git log <upstream>..HEAD (or git log HEAD, if --root is specified). The current branch is reset to <upstream>, or <newbase> if the --onto option was supplied. This has the exact same effect as git reset --hard <upstream> (or <newbase>). ORIG_HEAD is set to point at the tip of the branch before the reset. The commits that were previously saved into the temporary area are then reapplied to the current branch, one by one, in order. Note that any commits in HEAD which introduce the same textual changes as a commit in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream with a different commit message or timestamp will be skipped). It is possible that a merge failure will prevent this process from being completely automatic. You will have to resolve any such merge failure and run git rebase --continue. Another option is to bypass the commit that caused the merge failure with git rebase --skip. To check out the original <branch> and remove the .git/rebase-apply working files, use the command git rebase --abort instead. Assume the following history exists and the current branch is "topic": From this point, the result of either of the following commands: would be: NOTE: The latter form is just a short-hand of git checkout topic followed by git rebase master. When rebase exits topic will remain the checked-out branch. If the upstream branch already contains a change you have made (e.g., because you mailed a patch which was applied upstream), then that commit will be skipped. For example, running ‘git rebase master` on the following history (in which A’ and A introduce the same set of changes, but have different committer information): will result in: Here is how you would transplant a topic branch based on one branch to another, to pretend that you forked the topic branch from the latter branch, using rebase --onto. First let’s assume your topic is based on branch next. For example, a feature developed in topic depends on some functionality which is found in next. We want to make topic forked from branch master; for example, because the functionality on which topic depends was merged into the more stable master branch. We want our tree to look like this: We can get this using the following command: Another example of --onto option is to rebase part of a branch. If we have the following situation: then the command would result in: This is useful when topicB does not depend on topicA. A range of commits could also be removed with rebase. If we have the following situation: then the command would result in the removal of commits F and G: This is useful if F and G were flawed in some way, or should not be part of topicA. Note that the argument to --onto and the <upstream> parameter can be any valid commit-ish. In case of conflict, git rebase will stop at the first problematic commit and leave conflict markers in the tree. You can use git diff to locate the markers (<<<<<<) and make edits to resolve the conflict. For each file you edit, you need to tell Git that the conflict has been resolved, typically this would be done with After resolving the conflict manually and updating the index with the desired resolution, you can continue the rebasing process with Alternatively, you can undo the git rebase with

CONFIGURATION¶

rebase.stat rebase.autosquash rebase.autostash

OPTIONS¶

--onto <newbase> <upstream> <branch> --continue --abort --keep-empty --skip --edit-todo -m, --merge -s <strategy>, --strategy=<strategy> -X <strategy-option>, --strategy-option=<strategy-option> -S[<keyid>], --gpg-sign[=<keyid>] -q, --quiet -v, --verbose --stat -n, --no-stat --no-verify --verify -C<n> -f, --force-rebase --fork-point, --no-fork-point --ignore-whitespace, --whitespace=<option> --committer-date-is-author-date, --ignore-date -i, --interactive -p, --preserve-merges -x <cmd>, --exec <cmd> --root --autosquash, --no-autosquash --[no-]autostash --no-ff

MERGE STRATEGIES¶

The merge mechanism (git merge and git pull commands) allows the backend merge strategies to be chosen with -s option. Some strategies can also take their own options, which can be passed by giving -X<option> arguments to git merge and/or git pull. resolve recursive octopus ours subtree With the strategies that use 3-way merge (including the default, recursive), if a change is made on both branches, but later reverted on one of the branches, that change will be present in the merged result; some people find this behavior confusing. It occurs because only the heads and the merge base are considered when performing a merge, not the individual commits. The merge algorithm therefore considers the reverted change as no change at all, and substitutes the changed version instead.

NOTES¶

You should understand the implications of using git rebase on a repository that you share. See also RECOVERING FROM UPSTREAM REBASE below. When the git-rebase command is run, it will first execute a "pre-rebase" hook if one exists. You can use this hook to do sanity checks and reject the rebase if it isn’t appropriate. Please see the template pre-rebase hook script for an example. Upon completion, <branch> will be the current branch.

INTERACTIVE MODE¶

Rebasing interactively means that you have a chance to edit the commits which are rebased. You can reorder the commits, and you can remove them (weeding out bad or otherwise unwanted patches). The interactive mode is meant for this type of workflow: where point 2. consists of several instances of a) regular use b) independent fixup Sometimes the thing fixed in b.2. cannot be amended to the not-quite perfect commit it fixes, because that commit is buried deeply in a patch series. That is exactly what interactive rebase is for: use it after plenty of "a"s and "b"s, by rearranging and editing commits, and squashing multiple commits into one. Start it with the last commit you want to retain as-is: An editor will be fired up with all the commits in your current branch (ignoring merge commits), which come after the given commit. You can reorder the commits in this list to your heart’s content, and you can remove them. The list looks more or less like this: The oneline descriptions are purely for your pleasure; git rebase will not look at them but at the commit names ("deadbee" and "fa1afe1" in this example), so do not delete or edit the names. By replacing the command "pick" with the command "edit", you can tell git rebase to stop after applying that commit, so that you can edit the files and/or the commit message, amend the commit, and continue rebasing. If you just want to edit the commit message for a commit, replace the command "pick" with the command "reword". If you want to fold two or more commits into one, replace the command "pick" for the second and subsequent commits with "squash" or "fixup". If the commits had different authors, the folded commit will be attributed to the author of the first commit. The suggested commit message for the folded commit is the concatenation of the commit messages of the first commit and of those with the "squash" command, but omits the commit messages of commits with the "fixup" command. git rebase will stop when "pick" has been replaced with "edit" or when a command fails due to merge errors. When you are done editing and/or resolving conflicts you can continue with git rebase --continue. For example, if you want to reorder the last 5 commits, such that what was HEAD~4 becomes the new HEAD. To achieve that, you would call git rebase like this: And move the first patch to the end of the list. You might want to preserve merges, if you have a history like this: Suppose you want to rebase the side branch starting at "A" to "Q". Make sure that the current HEAD is "B", and call Reordering and editing commits usually creates untested intermediate steps. You may want to check that your history editing did not break anything by running a test, or at least recompiling at intermediate points in history by using the "exec" command (shortcut "x"). You may do so by creating a todo list like this one: The interactive rebase will stop when a command fails (i.e. exits with non-0 status) to give you an opportunity to fix the problem. You can continue with git rebase --continue. The "exec" command launches the command in a shell (the one specified in $SHELL, or the default shell if $SHELL is not set), so you can use shell features (like "cd", ">", ";" ...). The command is run from the root of the working tree. This command lets you check that intermediate commits are compilable. The todo list becomes like that:

SPLITTING COMMITS¶

In interactive mode, you can mark commits with the action "edit". However, this does not necessarily mean that git rebase expects the result of this edit to be exactly one commit. Indeed, you can undo the commit, or you can add other commits. This can be used to split a commit into two: If you are not absolutely sure that the intermediate revisions are consistent (they compile, pass the testsuite, etc.) you should use git stash to stash away the not-yet-committed changes after each commit, test, and amend the commit if fixes are necessary.

RECOVERING FROM UPSTREAM REBASE¶

Rebasing (or any other form of rewriting) a branch that others have based work on is a bad idea: anyone downstream of it is forced to manually fix their history. This section explains how to do the fix from the downstream’s point of view. The real fix, however, would be to avoid rebasing the upstream in the first place. To illustrate, suppose you are in a situation where someone develops a subsystem branch, and you are working on a topic that is dependent on this subsystem. You might end up with a history like the following: If subsystem is rebased against master, the following happens: If you now continue development as usual, and eventually merge topic to subsystem, the commits from subsystem will remain duplicated forever: Such duplicates are generally frowned upon because they clutter up history, making it harder to follow. To clean things up, you need to transplant the commits on topic to the new subsystem tip, i.e., rebase topic. This becomes a ripple effect: anyone downstream from topic is forced to rebase too, and so on! There are two kinds of fixes, discussed in the following subsections: Easy case: The changes are literally the same. Hard case: The changes are not the same.

The easy case¶

Only works if the changes (patch IDs based on the diff contents) on subsystem are literally the same before and after the rebase subsystem did. In that case, the fix is easy because git rebase knows to skip changes that are already present in the new upstream. So if you say (assuming you’re on topic) you will end up with the fixed history

The hard case¶

Things get more complicated if the subsystem changes do not exactly correspond to the ones before the rebase. The idea is to manually tell git rebase "where the old subsystem ended and your topic began", that is, what the old merge-base between them was. You will have to find a way to name the last commit of the old subsystem, for example: You can then transplant the old subsystem..topic to the new tip by saying (for the reflog case, and assuming you are on topic already): The ripple effect of a "hard case" recovery is especially bad: everyone downstream from topic will now have to perform a "hard case" recovery too!

BUGS¶

The todo list presented by --preserve-merges --interactive does not represent the topology of the revision graph. Editing commits and rewording their commit messages should work fine, but attempts to reorder commits tend to produce counterintuitive results. For example, an attempt to rearrange to by moving the "pick 4" line will result in the following history:

GIT¶

Part of the git(1) suite

NOTES¶

1.

revert-a-faulty-merge How-To