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Diffstat (limited to 'Documentation/git-rebase.txt')
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diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt index 96907d4863..ca5e1e8653 100644 --- a/Documentation/git-rebase.txt +++ b/Documentation/git-rebase.txt @@ -8,33 +8,41 @@ git-rebase - Forward-port local commits to the updated upstream head SYNOPSIS -------- [verse] -'git-rebase' [-i | --interactive] [-v | --verbose] [--merge] [-C<n>] - [-p | --preserve-merges] [--onto <newbase>] <upstream> [<branch>] -'git-rebase' --continue | --skip | --abort +'git rebase' [-i | --interactive] [options] [--onto <newbase>] + <upstream> [<branch>] +'git rebase' [-i | --interactive] [options] --onto <newbase> + --root [<branch>] + +'git rebase' --continue | --skip | --abort DESCRIPTION ----------- -If <branch> is specified, git-rebase will perform an automatic +If <branch> is specified, 'git-rebase' will perform an automatic `git checkout <branch>` before doing anything else. Otherwise it remains on the current branch. 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`. +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>). +`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. +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 restore the -original <branch> and remove the .dotest working files, use the command -`git rebase --abort` instead. +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": @@ -47,8 +55,8 @@ Assume the following history exists and the current branch is "topic": From this point, the result of either of the following commands: - git-rebase master - git-rebase master topic + git rebase master + git rebase master topic would be: @@ -61,12 +69,32 @@ would be: The latter form is just a short-hand of `git checkout topic` followed by `git rebase master`. +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): + +------------ + A---B---C topic + / + D---E---A'---F master +------------ + +will result in: + +------------ + B'---C' topic + / + D---E---A'---F master +------------ + 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 feature developed in 'topic' depends on some +For example, a feature developed in 'topic' depends on some functionality which is found in 'next'. ------------ @@ -77,9 +105,9 @@ functionality which is found in 'next'. o---o---o topic ------------ -We would want to make 'topic' forked from branch 'master', -for example because the functionality 'topic' branch depend on -got merged into more stable 'master' branch, like this: +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: ------------ o---o---o---o---o master @@ -91,7 +119,7 @@ got merged into more stable 'master' branch, like this: We can get this using the following command: - git-rebase --onto master next topic + git rebase --onto master next topic Another example of --onto option is to rebase part of a @@ -107,7 +135,7 @@ branch. If we have the following situation: then the command - git-rebase --onto master topicA topicB + git rebase --onto master topicA topicB would result in: @@ -130,7 +158,7 @@ the following situation: then the command - git-rebase --onto topicA~5 topicA~2 topicA + git rebase --onto topicA~5 topicA~3 topicA would result in the removal of commits F and G: @@ -142,8 +170,8 @@ 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 +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 @@ -159,11 +187,18 @@ desired resolution, you can continue the rebasing process with git rebase --continue -Alternatively, you can undo the git-rebase with +Alternatively, you can undo the 'git-rebase' with git rebase --abort +CONFIGURATION +------------- + +rebase.stat:: + Whether to show a diffstat of what changed upstream since the last + rebase. False by default. + OPTIONS ------- <newbase>:: @@ -188,20 +223,47 @@ OPTIONS --skip:: Restart the rebasing process by skipping the current patch. +-m:: --merge:: Use merging strategies to rebase. When the recursive (default) merge strategy is used, this allows rebase to be aware of renames on the upstream side. - --s <strategy>, \--strategy=<strategy>:: - Use the given merge strategy; can be supplied more than - once to specify them in the order they should be tried. - If there is no `-s` option, a built-in list of strategies - is used instead (`git-merge-recursive` when merging a single - head, `git-merge-octopus` otherwise). This implies --merge. - --v, \--verbose:: - Display a diffstat of what changed upstream since the last rebase. ++ +Note that a rebase merge works by replaying each commit from the working +branch on top of the <upstream> branch. Because of this, when a merge +conflict happens, the side reported as 'ours' is the so-far rebased +series, starting with <upstream>, and 'theirs' is the working branch. In +other words, the sides are swapped. + +-s <strategy>:: +--strategy=<strategy>:: + Use the given merge strategy. + If there is no `-s` option 'git-merge-recursive' is used + instead. This implies --merge. ++ +Because 'git-rebase' replays each commit from the working branch +on top of the <upstream> branch using the given strategy, using +the 'ours' strategy simply discards all patches from the <branch>, +which makes little sense. + +-q:: +--quiet:: + Be quiet. Implies --no-stat. + +-v:: +--verbose:: + Be verbose. Implies --stat. + +--stat:: + Show a diffstat of what changed upstream since the last rebase. The + diffstat is also controlled by the configuration option rebase.stat. + +-n:: +--no-stat:: + Do not show a diffstat as part of the rebase process. + +--no-verify:: + This option bypasses the pre-rebase hook. See also linkgit:githooks[5]. -C<n>:: Ensure at least <n> lines of surrounding context match before @@ -209,31 +271,58 @@ OPTIONS context exist they all must match. By default no context is ever ignored. --i, \--interactive:: +-f:: +--force-rebase:: + Force the rebase even if the current branch is a descendant + of the commit you are rebasing onto. Normally the command will + exit with the message "Current branch is up to date" in such a + situation. + +--ignore-whitespace:: +--whitespace=<option>:: + These flag are passed to the 'git-apply' program + (see linkgit:git-apply[1]) that applies the patch. + Incompatible with the --interactive option. + +--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]). + +-i:: +--interactive:: Make a list of the commits which are about to be rebased. Let the - user edit that list before rebasing. - --p, \--preserve-merges:: - Instead of ignoring merges, try to recreate them. This option - only works in interactive mode. + user edit that list before rebasing. This mode can also be used to + split commits (see SPLITTING COMMITS below). + +-p:: +--preserve-merges:: + Instead of ignoring merges, try to recreate them. + +--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. Must be used with --onto, and + will skip changes already contained in <newbase> (instead of + <upstream>). When used together with --preserve-merges, 'all' + root commits will be rewritten to have <newbase> as parent + instead. include::merge-strategies.txt[] NOTES ----- -When you rebase a branch, you are changing its history in a way that -will cause problems for anyone who already has a copy of the branch -in their repository and tries to pull updates from you. You should -understand the implications of using 'git rebase' on a repository that -you share. -When the git rebase command is run, it will first execute a "pre-rebase" +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. -You must be in the top directory of your project to start (or continue) -a rebase. Upon completion, <branch> will be the current branch. +Upon completion, <branch> will be the current branch. INTERACTIVE MODE ---------------- @@ -280,27 +369,30 @@ pick fa1afe1 The oneline of the next commit ... ------------------------------------------- -The oneline descriptions are purely for your pleasure; `git-rebase` will +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 +'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" with "squash" for the second and subsequent commit. If the commits had different authors, it will attribute the squashed commit to -the author of the last commit. +the author of the first commit. -In both cases, or when a "pick" does not succeed (because of merge -errors), the loop will stop to let you fix things, and you can continue -the loop with `git rebase --continue`. +'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' like this: ---------------------- $ git rebase -i HEAD~5 @@ -325,9 +417,166 @@ sure that the current HEAD is "B", and call $ git rebase -i -p --onto Q O ----------------------------- + +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---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, or squash commits; or if the + upstream used one of `commit \--amend`, `reset`, or + `filter-branch`. + + +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') +------------ + $ 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! + + Authors ------ -Written by Junio C Hamano <junkio@cox.net> and +Written by Junio C Hamano <gitster@pobox.com> and Johannes E. Schindelin <johannes.schindelin@gmx.de> Documentation @@ -336,4 +585,4 @@ Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>. GIT --- -Part of the gitlink:git[7] suite +Part of the linkgit:git[1] suite |