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1263 lines
44 KiB
1263 lines
44 KiB
git-rebase(1) |
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============= |
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NAME |
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---- |
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git-rebase - Reapply commits on top of another base tip |
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SYNOPSIS |
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-------- |
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[verse] |
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'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] |
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[--onto <newbase> | --keep-base] [<upstream> [<branch>]] |
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'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>] |
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--root [<branch>] |
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'git rebase' (--continue | --skip | --abort | --quit | --edit-todo | --show-current-patch) |
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DESCRIPTION |
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----------- |
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If <branch> is specified, 'git rebase' will perform an automatic |
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`git switch <branch>` before doing anything else. Otherwise |
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it remains on the current branch. |
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If <upstream> is not specified, the upstream configured in |
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branch.<name>.remote and branch.<name>.merge options will be used (see |
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linkgit:git-config[1] for details) and the `--fork-point` option is |
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assumed. If you are currently not on any branch or if the current |
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branch does not have a configured upstream, the rebase will abort. |
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All changes made by commits in the current branch but that are not |
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in <upstream> are saved to a temporary area. This is the same set |
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of commits that would be shown by `git log <upstream>..HEAD`; or by |
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`git log 'fork_point'..HEAD`, if `--fork-point` is active (see the |
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description on `--fork-point` below); or by `git log HEAD`, if the |
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`--root` option is specified. |
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The current branch is reset to <upstream>, or <newbase> if the |
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--onto option was supplied. This has the exact same effect as |
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`git reset --hard <upstream>` (or <newbase>). ORIG_HEAD is set |
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to point at the tip of the branch before the reset. |
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The commits that were previously saved into the temporary area are |
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then reapplied to the current branch, one by one, in order. Note that |
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any commits in HEAD which introduce the same textual changes as a commit |
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in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream |
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with a different commit message or timestamp will be skipped). |
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It is possible that a merge failure will prevent this process from being |
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completely automatic. You will have to resolve any such merge failure |
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and run `git rebase --continue`. Another option is to bypass the commit |
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that caused the merge failure with `git rebase --skip`. To check out the |
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original <branch> and remove the .git/rebase-apply working files, use the |
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command `git rebase --abort` instead. |
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Assume the following history exists and the current branch is "topic": |
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------------ |
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A---B---C topic |
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/ |
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D---E---F---G master |
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------------ |
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From this point, the result of either of the following commands: |
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git rebase master |
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git rebase master topic |
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would be: |
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------------ |
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A'--B'--C' topic |
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/ |
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D---E---F---G master |
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------------ |
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*NOTE:* The latter form is just a short-hand of `git checkout topic` |
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followed by `git rebase master`. When rebase exits `topic` will |
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remain the checked-out branch. |
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If the upstream branch already contains a change you have made (e.g., |
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because you mailed a patch which was applied upstream), then that commit |
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will be skipped. For example, running `git rebase master` on the |
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following history (in which `A'` and `A` introduce the same set of changes, |
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but have different committer information): |
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------------ |
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A---B---C topic |
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/ |
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D---E---A'---F master |
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------------ |
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will result in: |
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------------ |
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B'---C' topic |
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/ |
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D---E---A'---F master |
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------------ |
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Here is how you would transplant a topic branch based on one |
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branch to another, to pretend that you forked the topic branch |
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from the latter branch, using `rebase --onto`. |
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First let's assume your 'topic' is based on branch 'next'. |
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For example, a feature developed in 'topic' depends on some |
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functionality which is found in 'next'. |
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------------ |
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o---o---o---o---o master |
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\ |
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o---o---o---o---o next |
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\ |
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o---o---o topic |
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------------ |
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We want to make 'topic' forked from branch 'master'; for example, |
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because the functionality on which 'topic' depends was merged into the |
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more stable 'master' branch. We want our tree to look like this: |
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------------ |
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o---o---o---o---o master |
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| \ |
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| o'--o'--o' topic |
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\ |
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o---o---o---o---o next |
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------------ |
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We can get this using the following command: |
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git rebase --onto master next topic |
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Another example of --onto option is to rebase part of a |
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branch. If we have the following situation: |
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------------ |
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H---I---J topicB |
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/ |
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E---F---G topicA |
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/ |
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A---B---C---D master |
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------------ |
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then the command |
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git rebase --onto master topicA topicB |
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would result in: |
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------------ |
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H'--I'--J' topicB |
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/ |
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| E---F---G topicA |
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|/ |
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A---B---C---D master |
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------------ |
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This is useful when topicB does not depend on topicA. |
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A range of commits could also be removed with rebase. If we have |
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the following situation: |
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------------ |
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E---F---G---H---I---J topicA |
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------------ |
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then the command |
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git rebase --onto topicA~5 topicA~3 topicA |
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would result in the removal of commits F and G: |
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------------ |
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E---H'---I'---J' topicA |
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------------ |
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This is useful if F and G were flawed in some way, or should not be |
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part of topicA. Note that the argument to --onto and the <upstream> |
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parameter can be any valid commit-ish. |
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In case of conflict, 'git rebase' will stop at the first problematic commit |
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and leave conflict markers in the tree. You can use 'git diff' to locate |
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the markers (<<<<<<) and make edits to resolve the conflict. For each |
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file you edit, you need to tell Git that the conflict has been resolved, |
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typically this would be done with |
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git add <filename> |
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After resolving the conflict manually and updating the index with the |
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desired resolution, you can continue the rebasing process with |
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git rebase --continue |
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Alternatively, you can undo the 'git rebase' with |
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git rebase --abort |
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CONFIGURATION |
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------------- |
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include::config/rebase.txt[] |
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OPTIONS |
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------- |
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--onto <newbase>:: |
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Starting point at which to create the new commits. If the |
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--onto option is not specified, the starting point is |
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<upstream>. May be any valid commit, and not just an |
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existing branch name. |
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+ |
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As a special case, you may use "A\...B" as a shortcut for the |
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merge base of A and B if there is exactly one merge base. You can |
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leave out at most one of A and B, in which case it defaults to HEAD. |
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--keep-base:: |
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Set the starting point at which to create the new commits to the |
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merge base of <upstream> <branch>. Running |
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'git rebase --keep-base <upstream> <branch>' is equivalent to |
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running 'git rebase --onto <upstream>... <upstream>'. |
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+ |
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This option is useful in the case where one is developing a feature on |
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top of an upstream branch. While the feature is being worked on, the |
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upstream branch may advance and it may not be the best idea to keep |
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rebasing on top of the upstream but to keep the base commit as-is. |
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+ |
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Although both this option and --fork-point find the merge base between |
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<upstream> and <branch>, this option uses the merge base as the _starting |
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point_ on which new commits will be created, whereas --fork-point uses |
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the merge base to determine the _set of commits_ which will be rebased. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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<upstream>:: |
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Upstream branch to compare against. May be any valid commit, |
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not just an existing branch name. Defaults to the configured |
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upstream for the current branch. |
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<branch>:: |
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Working branch; defaults to HEAD. |
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--continue:: |
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Restart the rebasing process after having resolved a merge conflict. |
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--abort:: |
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Abort the rebase operation and reset HEAD to the original |
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branch. If <branch> was provided when the rebase operation was |
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started, then HEAD will be reset to <branch>. Otherwise HEAD |
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will be reset to where it was when the rebase operation was |
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started. |
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--quit:: |
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Abort the rebase operation but HEAD is not reset back to the |
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original branch. The index and working tree are also left |
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unchanged as a result. If a temporary stash entry was created |
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using --autostash, it will be saved to the stash list. |
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--apply:: |
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Use applying strategies to rebase (calling `git-am` |
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internally). This option may become a no-op in the future |
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once the merge backend handles everything the apply one does. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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--empty={drop,keep,ask}:: |
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How to handle commits that are not empty to start and are not |
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clean cherry-picks of any upstream commit, but which become |
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empty after rebasing (because they contain a subset of already |
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upstream changes). With drop (the default), commits that |
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become empty are dropped. With keep, such commits are kept. |
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With ask (implied by --interactive), the rebase will halt when |
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an empty commit is applied allowing you to choose whether to |
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drop it, edit files more, or just commit the empty changes. |
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Other options, like --exec, will use the default of drop unless |
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-i/--interactive is explicitly specified. |
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+ |
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Note that commits which start empty are kept (unless --no-keep-empty |
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is specified), and commits which are clean cherry-picks (as determined |
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by `git log --cherry-mark ...`) are detected and dropped as a |
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preliminary step (unless --reapply-cherry-picks is passed). |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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--no-keep-empty:: |
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--keep-empty:: |
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Do not keep commits that start empty before the rebase |
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(i.e. that do not change anything from its parent) in the |
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result. The default is to keep commits which start empty, |
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since creating such commits requires passing the --allow-empty |
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override flag to `git commit`, signifying that a user is very |
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intentionally creating such a commit and thus wants to keep |
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it. |
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+ |
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Usage of this flag will probably be rare, since you can get rid of |
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commits that start empty by just firing up an interactive rebase and |
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removing the lines corresponding to the commits you don't want. This |
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flag exists as a convenient shortcut, such as for cases where external |
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tools generate many empty commits and you want them all removed. |
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+ |
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For commits which do not start empty but become empty after rebasing, |
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see the --empty flag. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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--reapply-cherry-picks:: |
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--no-reapply-cherry-picks:: |
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Reapply all clean cherry-picks of any upstream commit instead |
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of preemptively dropping them. (If these commits then become |
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empty after rebasing, because they contain a subset of already |
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upstream changes, the behavior towards them is controlled by |
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the `--empty` flag.) |
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+ |
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By default (or if `--no-reapply-cherry-picks` is given), these commits |
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will be automatically dropped. Because this necessitates reading all |
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upstream commits, this can be expensive in repos with a large number |
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of upstream commits that need to be read. |
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+ |
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`--reapply-cherry-picks` allows rebase to forgo reading all upstream |
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commits, potentially improving performance. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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--allow-empty-message:: |
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No-op. Rebasing commits with an empty message used to fail |
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and this option would override that behavior, allowing commits |
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with empty messages to be rebased. Now commits with an empty |
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message do not cause rebasing to halt. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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--skip:: |
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Restart the rebasing process by skipping the current patch. |
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--edit-todo:: |
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Edit the todo list during an interactive rebase. |
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--show-current-patch:: |
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Show the current patch in an interactive rebase or when rebase |
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is stopped because of conflicts. This is the equivalent of |
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`git show REBASE_HEAD`. |
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-m:: |
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--merge:: |
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Use merging strategies to rebase. When the recursive (default) merge |
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strategy is used, this allows rebase to be aware of renames on the |
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upstream side. This is the default. |
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+ |
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Note that a rebase merge works by replaying each commit from the working |
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branch on top of the <upstream> branch. Because of this, when a merge |
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conflict happens, the side reported as 'ours' is the so-far rebased |
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series, starting with <upstream>, and 'theirs' is the working branch. In |
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other words, the sides are swapped. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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-s <strategy>:: |
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--strategy=<strategy>:: |
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Use the given merge strategy. |
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If there is no `-s` option 'git merge-recursive' is used |
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instead. This implies --merge. |
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+ |
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Because 'git rebase' replays each commit from the working branch |
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on top of the <upstream> branch using the given strategy, using |
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the 'ours' strategy simply empties all patches from the <branch>, |
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which makes little sense. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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-X <strategy-option>:: |
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--strategy-option=<strategy-option>:: |
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Pass the <strategy-option> through to the merge strategy. |
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This implies `--merge` and, if no strategy has been |
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specified, `-s recursive`. Note the reversal of 'ours' and |
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'theirs' as noted above for the `-m` option. |
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+ |
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See also INCOMPATIBLE OPTIONS below. |
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--rerere-autoupdate:: |
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--no-rerere-autoupdate:: |
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Allow the rerere mechanism to update the index with the |
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result of auto-conflict resolution if possible. |
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-S[<keyid>]:: |
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--gpg-sign[=<keyid>]:: |
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--no-gpg-sign:: |
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GPG-sign commits. The `keyid` argument is optional and |
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defaults to the committer identity; if specified, it must be |
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stuck to the option without a space. `--no-gpg-sign` is useful to |
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countermand both `commit.gpgSign` configuration variable, and |
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earlier `--gpg-sign`. |
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-q:: |
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--quiet:: |
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Be quiet. Implies --no-stat. |
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-v:: |
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--verbose:: |
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Be verbose. Implies --stat. |
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--stat:: |
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Show a diffstat of what changed upstream since the last rebase. The |
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diffstat is also controlled by the configuration option rebase.stat. |
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-n:: |
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--no-stat:: |
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Do not show a diffstat as part of the rebase process. |
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--no-verify:: |
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This option bypasses the pre-rebase hook. See also linkgit:githooks[5]. |
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--verify:: |
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Allows the pre-rebase hook to run, which is the default. This option can |
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be used to override --no-verify. See also linkgit:githooks[5]. |
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-C<n>:: |
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Ensure at least <n> lines of surrounding context match before |
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and after each change. When fewer lines of surrounding |
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context exist they all must match. By default no context is |
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ever ignored. Implies --apply. |
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+ |
|
See also INCOMPATIBLE OPTIONS below. |
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--no-ff:: |
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--force-rebase:: |
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-f:: |
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Individually replay all rebased commits instead of fast-forwarding |
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over the unchanged ones. This ensures that the entire history of |
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the rebased branch is composed of new commits. |
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+ |
|
You may find this helpful after reverting a topic branch merge, as this option |
|
recreates the topic branch with fresh commits so it can be remerged |
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successfully without needing to "revert the reversion" (see the |
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link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for |
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details). |
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--fork-point:: |
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--no-fork-point:: |
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Use reflog to find a better common ancestor between <upstream> |
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and <branch> when calculating which commits have been |
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introduced by <branch>. |
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+ |
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When --fork-point is active, 'fork_point' will be used instead of |
|
<upstream> to calculate the set of commits to rebase, where |
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'fork_point' is the result of `git merge-base --fork-point <upstream> |
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<branch>` command (see linkgit:git-merge-base[1]). If 'fork_point' |
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ends up being empty, the <upstream> will be used as a fallback. |
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+ |
|
If <upstream> is given on the command line, then the default is |
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`--no-fork-point`, otherwise the default is `--fork-point`. |
|
+ |
|
If your branch was based on <upstream> but <upstream> was rewound and |
|
your branch contains commits which were dropped, this option can be used |
|
with `--keep-base` in order to drop those commits from your branch. |
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+ |
|
See also INCOMPATIBLE OPTIONS below. |
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--ignore-whitespace:: |
|
--whitespace=<option>:: |
|
These flags are passed to the 'git apply' program |
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(see linkgit:git-apply[1]) that applies the patch. |
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Implies --apply. |
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+ |
|
See also INCOMPATIBLE OPTIONS below. |
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|
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--committer-date-is-author-date:: |
|
--ignore-date:: |
|
These flags are passed to 'git am' to easily change the dates |
|
of the rebased commits (see linkgit:git-am[1]). |
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+ |
|
See also INCOMPATIBLE OPTIONS below. |
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--signoff:: |
|
Add a Signed-off-by: trailer to all the rebased commits. Note |
|
that if `--interactive` is given then only commits marked to be |
|
picked, edited or reworded will have the trailer added. |
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+ |
|
See also INCOMPATIBLE OPTIONS below. |
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|
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-i:: |
|
--interactive:: |
|
Make a list of the commits which are about to be rebased. Let the |
|
user edit that list before rebasing. This mode can also be used to |
|
split commits (see SPLITTING COMMITS below). |
|
+ |
|
The commit list format can be changed by setting the configuration option |
|
rebase.instructionFormat. A customized instruction format will automatically |
|
have the long commit hash prepended to the format. |
|
+ |
|
See also INCOMPATIBLE OPTIONS below. |
|
|
|
-r:: |
|
--rebase-merges[=(rebase-cousins|no-rebase-cousins)]:: |
|
By default, a rebase will simply drop merge commits from the todo |
|
list, and put the rebased commits into a single, linear branch. |
|
With `--rebase-merges`, the rebase will instead try to preserve |
|
the branching structure within the commits that are to be rebased, |
|
by recreating the merge commits. Any resolved merge conflicts or |
|
manual amendments in these merge commits will have to be |
|
resolved/re-applied manually. |
|
+ |
|
By default, or when `no-rebase-cousins` was specified, commits which do not |
|
have `<upstream>` as direct ancestor will keep their original branch point, |
|
i.e. commits that would be excluded by linkgit:git-log[1]'s |
|
`--ancestry-path` option will keep their original ancestry by default. If |
|
the `rebase-cousins` mode is turned on, such commits are instead rebased |
|
onto `<upstream>` (or `<onto>`, if specified). |
|
+ |
|
The `--rebase-merges` mode is similar in spirit to the deprecated |
|
`--preserve-merges` but works with interactive rebases, |
|
where commits can be reordered, inserted and dropped at will. |
|
+ |
|
It is currently only possible to recreate the merge commits using the |
|
`recursive` merge strategy; Different merge strategies can be used only via |
|
explicit `exec git merge -s <strategy> [...]` commands. |
|
+ |
|
See also REBASING MERGES and INCOMPATIBLE OPTIONS below. |
|
|
|
-p:: |
|
--preserve-merges:: |
|
[DEPRECATED: use `--rebase-merges` instead] Recreate merge commits |
|
instead of flattening the history by replaying commits a merge commit |
|
introduces. Merge conflict resolutions or manual amendments to merge |
|
commits are not preserved. |
|
+ |
|
This uses the `--interactive` machinery internally, but combining it |
|
with the `--interactive` option explicitly is generally not a good |
|
idea unless you know what you are doing (see BUGS below). |
|
+ |
|
See also INCOMPATIBLE OPTIONS below. |
|
|
|
-x <cmd>:: |
|
--exec <cmd>:: |
|
Append "exec <cmd>" after each line creating a commit in the |
|
final history. <cmd> will be interpreted as one or more shell |
|
commands. Any command that fails will interrupt the rebase, |
|
with exit code 1. |
|
+ |
|
You may execute several commands by either using one instance of `--exec` |
|
with several commands: |
|
+ |
|
git rebase -i --exec "cmd1 && cmd2 && ..." |
|
+ |
|
or by giving more than one `--exec`: |
|
+ |
|
git rebase -i --exec "cmd1" --exec "cmd2" --exec ... |
|
+ |
|
If `--autosquash` is used, "exec" lines will not be appended for |
|
the intermediate commits, and will only appear at the end of each |
|
squash/fixup series. |
|
+ |
|
This uses the `--interactive` machinery internally, but it can be run |
|
without an explicit `--interactive`. |
|
+ |
|
See also INCOMPATIBLE OPTIONS below. |
|
|
|
--root:: |
|
Rebase all commits reachable from <branch>, instead of |
|
limiting them with an <upstream>. This allows you to rebase |
|
the root commit(s) on a branch. When used with --onto, it |
|
will skip changes already contained in <newbase> (instead of |
|
<upstream>) whereas without --onto it will operate on every change. |
|
When used together with both --onto and --preserve-merges, |
|
'all' root commits will be rewritten to have <newbase> as parent |
|
instead. |
|
+ |
|
See also INCOMPATIBLE OPTIONS below. |
|
|
|
--autosquash:: |
|
--no-autosquash:: |
|
When the commit log message begins with "squash! ..." (or |
|
"fixup! ..."), and there is already a commit in the todo list that |
|
matches the same `...`, automatically modify the todo list of rebase |
|
-i so that the commit marked for squashing comes right after the |
|
commit to be modified, and change the action of the moved commit |
|
from `pick` to `squash` (or `fixup`). A commit matches the `...` if |
|
the commit subject matches, or if the `...` refers to the commit's |
|
hash. As a fall-back, partial matches of the commit subject work, |
|
too. The recommended way to create fixup/squash commits is by using |
|
the `--fixup`/`--squash` options of linkgit:git-commit[1]. |
|
+ |
|
If the `--autosquash` option is enabled by default using the |
|
configuration variable `rebase.autoSquash`, this option can be |
|
used to override and disable this setting. |
|
+ |
|
See also INCOMPATIBLE OPTIONS below. |
|
|
|
--autostash:: |
|
--no-autostash:: |
|
Automatically create a temporary stash entry before the operation |
|
begins, and apply it after the operation ends. This means |
|
that you can run rebase on a dirty worktree. However, use |
|
with care: the final stash application after a successful |
|
rebase might result in non-trivial conflicts. |
|
|
|
--reschedule-failed-exec:: |
|
--no-reschedule-failed-exec:: |
|
Automatically reschedule `exec` commands that failed. This only makes |
|
sense in interactive mode (or when an `--exec` option was provided). |
|
|
|
INCOMPATIBLE OPTIONS |
|
-------------------- |
|
|
|
The following options: |
|
|
|
* --apply |
|
* --committer-date-is-author-date |
|
* --ignore-date |
|
* --ignore-whitespace |
|
* --whitespace |
|
* -C |
|
|
|
are incompatible with the following options: |
|
|
|
* --merge |
|
* --strategy |
|
* --strategy-option |
|
* --allow-empty-message |
|
* --[no-]autosquash |
|
* --rebase-merges |
|
* --preserve-merges |
|
* --interactive |
|
* --exec |
|
* --no-keep-empty |
|
* --empty= |
|
* --reapply-cherry-picks |
|
* --edit-todo |
|
* --root when used in combination with --onto |
|
|
|
In addition, the following pairs of options are incompatible: |
|
|
|
* --preserve-merges and --interactive |
|
* --preserve-merges and --signoff |
|
* --preserve-merges and --rebase-merges |
|
* --preserve-merges and --empty= |
|
* --keep-base and --onto |
|
* --keep-base and --root |
|
* --fork-point and --root |
|
|
|
BEHAVIORAL DIFFERENCES |
|
----------------------- |
|
|
|
git rebase has two primary backends: apply and merge. (The apply |
|
backend used to be known as the 'am' backend, but the name led to |
|
confusion as it looks like a verb instead of a noun. Also, the merge |
|
backend used to be known as the interactive backend, but it is now |
|
used for non-interactive cases as well. Both were renamed based on |
|
lower-level functionality that underpinned each.) There are some |
|
subtle differences in how these two backends behave: |
|
|
|
Empty commits |
|
~~~~~~~~~~~~~ |
|
|
|
The apply backend unfortunately drops intentionally empty commits, i.e. |
|
commits that started empty, though these are rare in practice. It |
|
also drops commits that become empty and has no option for controlling |
|
this behavior. |
|
|
|
The merge backend keeps intentionally empty commits by default (though |
|
with -i they are marked as empty in the todo list editor, or they can |
|
be dropped automatically with --no-keep-empty). |
|
|
|
Similar to the apply backend, by default the merge backend drops |
|
commits that become empty unless -i/--interactive is specified (in |
|
which case it stops and asks the user what to do). The merge backend |
|
also has an --empty={drop,keep,ask} option for changing the behavior |
|
of handling commits that become empty. |
|
|
|
Directory rename detection |
|
~~~~~~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
Due to the lack of accurate tree information (arising from |
|
constructing fake ancestors with the limited information available in |
|
patches), directory rename detection is disabled in the apply backend. |
|
Disabled directory rename detection means that if one side of history |
|
renames a directory and the other adds new files to the old directory, |
|
then the new files will be left behind in the old directory without |
|
any warning at the time of rebasing that you may want to move these |
|
files into the new directory. |
|
|
|
Directory rename detection works with the merge backend to provide you |
|
warnings in such cases. |
|
|
|
Context |
|
~~~~~~~ |
|
|
|
The apply backend works by creating a sequence of patches (by calling |
|
`format-patch` internally), and then applying the patches in sequence |
|
(calling `am` internally). Patches are composed of multiple hunks, |
|
each with line numbers, a context region, and the actual changes. The |
|
line numbers have to be taken with some fuzz, since the other side |
|
will likely have inserted or deleted lines earlier in the file. The |
|
context region is meant to help find how to adjust the line numbers in |
|
order to apply the changes to the right lines. However, if multiple |
|
areas of the code have the same surrounding lines of context, the |
|
wrong one can be picked. There are real-world cases where this has |
|
caused commits to be reapplied incorrectly with no conflicts reported. |
|
Setting diff.context to a larger value may prevent such types of |
|
problems, but increases the chance of spurious conflicts (since it |
|
will require more lines of matching context to apply). |
|
|
|
The merge backend works with a full copy of each relevant file, |
|
insulating it from these types of problems. |
|
|
|
Labelling of conflicts markers |
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
When there are content conflicts, the merge machinery tries to |
|
annotate each side's conflict markers with the commits where the |
|
content came from. Since the apply backend drops the original |
|
information about the rebased commits and their parents (and instead |
|
generates new fake commits based off limited information in the |
|
generated patches), those commits cannot be identified; instead it has |
|
to fall back to a commit summary. Also, when merge.conflictStyle is |
|
set to diff3, the apply backend will use "constructed merge base" to |
|
label the content from the merge base, and thus provide no information |
|
about the merge base commit whatsoever. |
|
|
|
The merge backend works with the full commits on both sides of history |
|
and thus has no such limitations. |
|
|
|
Hooks |
|
~~~~~ |
|
|
|
The apply backend has not traditionally called the post-commit hook, |
|
while the merge backend has. Both have called the post-checkout hook, |
|
though the merge backend has squelched its output. Further, both |
|
backends only call the post-checkout hook with the starting point |
|
commit of the rebase, not the intermediate commits nor the final |
|
commit. In each case, the calling of these hooks was by accident of |
|
implementation rather than by design (both backends were originally |
|
implemented as shell scripts and happened to invoke other commands |
|
like 'git checkout' or 'git commit' that would call the hooks). Both |
|
backends should have the same behavior, though it is not entirely |
|
clear which, if any, is correct. We will likely make rebase stop |
|
calling either of these hooks in the future. |
|
|
|
Interruptability |
|
~~~~~~~~~~~~~~~~ |
|
|
|
The apply backend has safety problems with an ill-timed interrupt; if |
|
the user presses Ctrl-C at the wrong time to try to abort the rebase, |
|
the rebase can enter a state where it cannot be aborted with a |
|
subsequent `git rebase --abort`. The merge backend does not appear to |
|
suffer from the same shortcoming. (See |
|
https://lore.kernel.org/git/20200207132152.GC2868@szeder.dev/ for |
|
details.) |
|
|
|
Commit Rewording |
|
~~~~~~~~~~~~~~~~ |
|
|
|
When a conflict occurs while rebasing, rebase stops and asks the user |
|
to resolve. Since the user may need to make notable changes while |
|
resolving conflicts, after conflicts are resolved and the user has run |
|
`git rebase --continue`, the rebase should open an editor and ask the |
|
user to update the commit message. The merge backend does this, while |
|
the apply backend blindly applies the original commit message. |
|
|
|
Miscellaneous differences |
|
~~~~~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
There are a few more behavioral differences that most folks would |
|
probably consider inconsequential but which are mentioned for |
|
completeness: |
|
|
|
* Reflog: The two backends will use different wording when describing |
|
the changes made in the reflog, though both will make use of the |
|
word "rebase". |
|
|
|
* Progress, informational, and error messages: The two backends |
|
provide slightly different progress and informational messages. |
|
Also, the apply backend writes error messages (such as "Your files |
|
would be overwritten...") to stdout, while the merge backend writes |
|
them to stderr. |
|
|
|
* State directories: The two backends keep their state in different |
|
directories under .git/ |
|
|
|
include::merge-strategies.txt[] |
|
|
|
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: |
|
|
|
1. have a wonderful idea |
|
2. hack on the code |
|
3. prepare a series for submission |
|
4. submit |
|
|
|
where point 2. consists of several instances of |
|
|
|
a) regular use |
|
|
|
1. finish something worthy of a commit |
|
2. commit |
|
|
|
b) independent fixup |
|
|
|
1. realize that something does not work |
|
2. fix that |
|
3. commit it |
|
|
|
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: |
|
|
|
git rebase -i <after-this-commit> |
|
|
|
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: |
|
|
|
------------------------------------------- |
|
pick deadbee The oneline of this commit |
|
pick fa1afe1 The oneline of the next commit |
|
... |
|
------------------------------------------- |
|
|
|
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. |
|
|
|
To interrupt the rebase (just like an "edit" command would do, but without |
|
cherry-picking any commit first), use the "break" command. |
|
|
|
If you just want to edit the commit message for a commit, replace the |
|
command "pick" with the command "reword". |
|
|
|
To drop a commit, replace the command "pick" with "drop", or just |
|
delete the matching line. |
|
|
|
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: |
|
|
|
---------------------- |
|
$ git rebase -i HEAD~5 |
|
---------------------- |
|
|
|
And move the first patch to the end of the list. |
|
|
|
You might want to recreate merge commits, e.g. if you have a history |
|
like this: |
|
|
|
------------------ |
|
X |
|
\ |
|
A---M---B |
|
/ |
|
---o---O---P---Q |
|
------------------ |
|
|
|
Suppose you want to rebase the side branch starting at "A" to "Q". Make |
|
sure that the current HEAD is "B", and call |
|
|
|
----------------------------- |
|
$ git rebase -i -r --onto Q O |
|
----------------------------- |
|
|
|
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: |
|
|
|
------------------------------------------- |
|
pick deadbee Implement feature XXX |
|
fixup f1a5c00 Fix to feature XXX |
|
exec make |
|
pick c0ffeee The oneline of the next commit |
|
edit deadbab The oneline of the commit after |
|
exec cd subdir; make test |
|
... |
|
------------------------------------------- |
|
|
|
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. |
|
|
|
---------------------------------- |
|
$ git rebase -i --exec "make test" |
|
---------------------------------- |
|
|
|
This command lets you check that intermediate commits are compilable. |
|
The todo list becomes like that: |
|
|
|
-------------------- |
|
pick 5928aea one |
|
exec make test |
|
pick 04d0fda two |
|
exec make test |
|
pick ba46169 three |
|
exec make test |
|
pick f4593f9 four |
|
exec make test |
|
-------------------- |
|
|
|
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: |
|
|
|
- Start an interactive rebase with `git rebase -i <commit>^`, where |
|
<commit> is the commit you want to split. In fact, any commit range |
|
will do, as long as it contains that commit. |
|
|
|
- Mark the commit you want to split with the action "edit". |
|
|
|
- When it comes to editing that commit, execute `git reset HEAD^`. The |
|
effect is that the HEAD is rewound by one, and the index follows suit. |
|
However, the working tree stays the same. |
|
|
|
- Now add the changes to the index that you want to have in the first |
|
commit. You can use `git add` (possibly interactively) or |
|
'git gui' (or both) to do that. |
|
|
|
- Commit the now-current index with whatever commit message is appropriate |
|
now. |
|
|
|
- Repeat the last two steps until your working tree is clean. |
|
|
|
- Continue the rebase with `git rebase --continue`. |
|
|
|
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: |
|
|
|
------------ |
|
o---o---o---o---o---o---o---o master |
|
\ |
|
o---o---o---o---o subsystem |
|
\ |
|
*---*---* topic |
|
------------ |
|
|
|
If 'subsystem' is rebased against 'master', the following happens: |
|
|
|
------------ |
|
o---o---o---o---o---o---o---o master |
|
\ \ |
|
o---o---o---o---o o'--o'--o'--o'--o' subsystem |
|
\ |
|
*---*---* topic |
|
------------ |
|
|
|
If you now continue development as usual, and eventually merge 'topic' |
|
to 'subsystem', the commits from 'subsystem' will remain duplicated forever: |
|
|
|
------------ |
|
o---o---o---o---o---o---o---o master |
|
\ \ |
|
o---o---o---o---o o'--o'--o'--o'--o'--M subsystem |
|
\ / |
|
*---*---*-..........-*--* topic |
|
------------ |
|
|
|
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.:: |
|
|
|
This happens if the 'subsystem' rebase was a simple rebase and |
|
had no conflicts. |
|
|
|
Hard case: The changes are not the same.:: |
|
|
|
This happens if the 'subsystem' rebase had conflicts, or used |
|
`--interactive` to omit, edit, squash, or fixup commits; or |
|
if the upstream used one of `commit --amend`, `reset`, or |
|
a full history rewriting command like |
|
https://github.com/newren/git-filter-repo[`filter-repo`]. |
|
|
|
|
|
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 (unless |
|
`--reapply-cherry-picks` is given). So if you say |
|
(assuming you're on 'topic') |
|
------------ |
|
$ git rebase subsystem |
|
------------ |
|
you will end up with the fixed history |
|
------------ |
|
o---o---o---o---o---o---o---o master |
|
\ |
|
o'--o'--o'--o'--o' subsystem |
|
\ |
|
*---*---* topic |
|
------------ |
|
|
|
|
|
The hard case |
|
~~~~~~~~~~~~~ |
|
|
|
Things get more complicated if the 'subsystem' changes do not exactly |
|
correspond to the ones before the rebase. |
|
|
|
NOTE: While an "easy case recovery" sometimes appears to be successful |
|
even in the hard case, it may have unintended consequences. For |
|
example, a commit that was removed via `git rebase |
|
--interactive` will be **resurrected**! |
|
|
|
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: |
|
|
|
* With the 'subsystem' reflog: after 'git fetch', the old tip of |
|
'subsystem' is at `subsystem@{1}`. Subsequent fetches will |
|
increase the number. (See linkgit:git-reflog[1].) |
|
|
|
* Relative to the tip of 'topic': knowing that your 'topic' has three |
|
commits, the old tip of 'subsystem' must be `topic~3`. |
|
|
|
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): |
|
------------ |
|
$ git rebase --onto subsystem subsystem@{1} |
|
------------ |
|
|
|
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! |
|
|
|
REBASING MERGES |
|
--------------- |
|
|
|
The interactive rebase command was originally designed to handle |
|
individual patch series. As such, it makes sense to exclude merge |
|
commits from the todo list, as the developer may have merged the |
|
then-current `master` while working on the branch, only to rebase |
|
all the commits onto `master` eventually (skipping the merge |
|
commits). |
|
|
|
However, there are legitimate reasons why a developer may want to |
|
recreate merge commits: to keep the branch structure (or "commit |
|
topology") when working on multiple, inter-related branches. |
|
|
|
In the following example, the developer works on a topic branch that |
|
refactors the way buttons are defined, and on another topic branch |
|
that uses that refactoring to implement a "Report a bug" button. The |
|
output of `git log --graph --format=%s -5` may look like this: |
|
|
|
------------ |
|
* Merge branch 'report-a-bug' |
|
|\ |
|
| * Add the feedback button |
|
* | Merge branch 'refactor-button' |
|
|\ \ |
|
| |/ |
|
| * Use the Button class for all buttons |
|
| * Extract a generic Button class from the DownloadButton one |
|
------------ |
|
|
|
The developer might want to rebase those commits to a newer `master` |
|
while keeping the branch topology, for example when the first topic |
|
branch is expected to be integrated into `master` much earlier than the |
|
second one, say, to resolve merge conflicts with changes to the |
|
DownloadButton class that made it into `master`. |
|
|
|
This rebase can be performed using the `--rebase-merges` option. |
|
It will generate a todo list looking like this: |
|
|
|
------------ |
|
label onto |
|
|
|
# Branch: refactor-button |
|
reset onto |
|
pick 123456 Extract a generic Button class from the DownloadButton one |
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pick 654321 Use the Button class for all buttons |
|
label refactor-button |
|
|
|
# Branch: report-a-bug |
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reset refactor-button # Use the Button class for all buttons |
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pick abcdef Add the feedback button |
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label report-a-bug |
|
|
|
reset onto |
|
merge -C a1b2c3 refactor-button # Merge 'refactor-button' |
|
merge -C 6f5e4d report-a-bug # Merge 'report-a-bug' |
|
------------ |
|
|
|
In contrast to a regular interactive rebase, there are `label`, `reset` |
|
and `merge` commands in addition to `pick` ones. |
|
|
|
The `label` command associates a label with the current HEAD when that |
|
command is executed. These labels are created as worktree-local refs |
|
(`refs/rewritten/<label>`) that will be deleted when the rebase |
|
finishes. That way, rebase operations in multiple worktrees linked to |
|
the same repository do not interfere with one another. If the `label` |
|
command fails, it is rescheduled immediately, with a helpful message how |
|
to proceed. |
|
|
|
The `reset` command resets the HEAD, index and worktree to the specified |
|
revision. It is similar to an `exec git reset --hard <label>`, but |
|
refuses to overwrite untracked files. If the `reset` command fails, it is |
|
rescheduled immediately, with a helpful message how to edit the todo list |
|
(this typically happens when a `reset` command was inserted into the todo |
|
list manually and contains a typo). |
|
|
|
The `merge` command will merge the specified revision(s) into whatever |
|
is HEAD at that time. With `-C <original-commit>`, the commit message of |
|
the specified merge commit will be used. When the `-C` is changed to |
|
a lower-case `-c`, the message will be opened in an editor after a |
|
successful merge so that the user can edit the message. |
|
|
|
If a `merge` command fails for any reason other than merge conflicts (i.e. |
|
when the merge operation did not even start), it is rescheduled immediately. |
|
|
|
At this time, the `merge` command will *always* use the `recursive` |
|
merge strategy for regular merges, and `octopus` for octopus merges, |
|
with no way to choose a different one. To work around |
|
this, an `exec` command can be used to call `git merge` explicitly, |
|
using the fact that the labels are worktree-local refs (the ref |
|
`refs/rewritten/onto` would correspond to the label `onto`, for example). |
|
|
|
Note: the first command (`label onto`) labels the revision onto which |
|
the commits are rebased; The name `onto` is just a convention, as a nod |
|
to the `--onto` option. |
|
|
|
It is also possible to introduce completely new merge commits from scratch |
|
by adding a command of the form `merge <merge-head>`. This form will |
|
generate a tentative commit message and always open an editor to let the |
|
user edit it. This can be useful e.g. when a topic branch turns out to |
|
address more than a single concern and wants to be split into two or |
|
even more topic branches. Consider this todo list: |
|
|
|
------------ |
|
pick 192837 Switch from GNU Makefiles to CMake |
|
pick 5a6c7e Document the switch to CMake |
|
pick 918273 Fix detection of OpenSSL in CMake |
|
pick afbecd http: add support for TLS v1.3 |
|
pick fdbaec Fix detection of cURL in CMake on Windows |
|
------------ |
|
|
|
The one commit in this list that is not related to CMake may very well |
|
have been motivated by working on fixing all those bugs introduced by |
|
switching to CMake, but it addresses a different concern. To split this |
|
branch into two topic branches, the todo list could be edited like this: |
|
|
|
------------ |
|
label onto |
|
|
|
pick afbecd http: add support for TLS v1.3 |
|
label tlsv1.3 |
|
|
|
reset onto |
|
pick 192837 Switch from GNU Makefiles to CMake |
|
pick 918273 Fix detection of OpenSSL in CMake |
|
pick fdbaec Fix detection of cURL in CMake on Windows |
|
pick 5a6c7e Document the switch to CMake |
|
label cmake |
|
|
|
reset onto |
|
merge tlsv1.3 |
|
merge cmake |
|
------------ |
|
|
|
BUGS |
|
---- |
|
The todo list presented by the deprecated `--preserve-merges --interactive` |
|
does not represent the topology of the revision graph (use `--rebase-merges` |
|
instead). Editing commits and rewording their commit messages should work |
|
fine, but attempts to reorder commits tend to produce counterintuitive results. |
|
Use `--rebase-merges` in such scenarios instead. |
|
|
|
For example, an attempt to rearrange |
|
------------ |
|
1 --- 2 --- 3 --- 4 --- 5 |
|
------------ |
|
to |
|
------------ |
|
1 --- 2 --- 4 --- 3 --- 5 |
|
------------ |
|
by moving the "pick 4" line will result in the following history: |
|
------------ |
|
3 |
|
/ |
|
1 --- 2 --- 4 --- 5 |
|
------------ |
|
|
|
GIT |
|
--- |
|
Part of the linkgit:git[1] suite
|
|
|