1git-rebase(1) 2============= 3 4NAME 5---- 6git-rebase - Reapply commits on top of another base tip 7 8SYNOPSIS 9-------- 10[verse] 11'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>] 12 [<upstream> [<branch>]] 13'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>] 14 --root [<branch>] 15'git rebase' --continue | --skip | --abort | --quit | --edit-todo | --show-current-patch 16 17DESCRIPTION 18----------- 19If <branch> is specified, 'git rebase' will perform an automatic 20`git checkout <branch>` before doing anything else. Otherwise 21it remains on the current branch. 22 23If <upstream> is not specified, the upstream configured in 24branch.<name>.remote and branch.<name>.merge options will be used (see 25linkgit:git-config[1] for details) and the `--fork-point` option is 26assumed. If you are currently not on any branch or if the current 27branch does not have a configured upstream, the rebase will abort. 28 29All changes made by commits in the current branch but that are not 30in <upstream> are saved to a temporary area. This is the same set 31of commits that would be shown by `git log <upstream>..HEAD`; or by 32`git log 'fork_point'..HEAD`, if `--fork-point` is active (see the 33description on `--fork-point` below); or by `git log HEAD`, if the 34`--root` option is specified. 35 36The current branch is reset to <upstream>, or <newbase> if the 37--onto option was supplied. This has the exact same effect as 38`git reset --hard <upstream>` (or <newbase>). ORIG_HEAD is set 39to point at the tip of the branch before the reset. 40 41The commits that were previously saved into the temporary area are 42then reapplied to the current branch, one by one, in order. Note that 43any commits in HEAD which introduce the same textual changes as a commit 44in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream 45with a different commit message or timestamp will be skipped). 46 47It is possible that a merge failure will prevent this process from being 48completely automatic. You will have to resolve any such merge failure 49and run `git rebase --continue`. Another option is to bypass the commit 50that caused the merge failure with `git rebase --skip`. To check out the 51original <branch> and remove the .git/rebase-apply working files, use the 52command `git rebase --abort` instead. 53 54Assume the following history exists and the current branch is "topic": 55 56------------ 57 A---B---C topic 58 / 59 D---E---F---G master 60------------ 61 62From this point, the result of either of the following commands: 63 64 65 git rebase master 66 git rebase master topic 67 68would be: 69 70------------ 71 A'--B'--C' topic 72 / 73 D---E---F---G master 74------------ 75 76*NOTE:* The latter form is just a short-hand of `git checkout topic` 77followed by `git rebase master`. When rebase exits `topic` will 78remain the checked-out branch. 79 80If the upstream branch already contains a change you have made (e.g., 81because you mailed a patch which was applied upstream), then that commit 82will be skipped. For example, running `git rebase master` on the 83following history (in which `A'` and `A` introduce the same set of changes, 84but have different committer information): 85 86------------ 87 A---B---C topic 88 / 89 D---E---A'---F master 90------------ 91 92will result in: 93 94------------ 95 B'---C' topic 96 / 97 D---E---A'---F master 98------------ 99 100Here is how you would transplant a topic branch based on one 101branch to another, to pretend that you forked the topic branch 102from the latter branch, using `rebase --onto`. 103 104First let's assume your 'topic' is based on branch 'next'. 105For example, a feature developed in 'topic' depends on some 106functionality which is found in 'next'. 107 108------------ 109 o---o---o---o---o master 110 \ 111 o---o---o---o---o next 112 \ 113 o---o---o topic 114------------ 115 116We want to make 'topic' forked from branch 'master'; for example, 117because the functionality on which 'topic' depends was merged into the 118more stable 'master' branch. We want our tree to look like this: 119 120------------ 121 o---o---o---o---o master 122 | \ 123 | o'--o'--o' topic 124 \ 125 o---o---o---o---o next 126------------ 127 128We can get this using the following command: 129 130 git rebase --onto master next topic 131 132 133Another example of --onto option is to rebase part of a 134branch. If we have the following situation: 135 136------------ 137 H---I---J topicB 138 / 139 E---F---G topicA 140 / 141 A---B---C---D master 142------------ 143 144then the command 145 146 git rebase --onto master topicA topicB 147 148would result in: 149 150------------ 151 H'--I'--J' topicB 152 / 153 | E---F---G topicA 154 |/ 155 A---B---C---D master 156------------ 157 158This is useful when topicB does not depend on topicA. 159 160A range of commits could also be removed with rebase. If we have 161the following situation: 162 163------------ 164 E---F---G---H---I---J topicA 165------------ 166 167then the command 168 169 git rebase --onto topicA~5 topicA~3 topicA 170 171would result in the removal of commits F and G: 172 173------------ 174 E---H'---I'---J' topicA 175------------ 176 177This is useful if F and G were flawed in some way, or should not be 178part of topicA. Note that the argument to --onto and the <upstream> 179parameter can be any valid commit-ish. 180 181In case of conflict, 'git rebase' will stop at the first problematic commit 182and leave conflict markers in the tree. You can use 'git diff' to locate 183the markers (<<<<<<) and make edits to resolve the conflict. For each 184file you edit, you need to tell Git that the conflict has been resolved, 185typically this would be done with 186 187 188 git add <filename> 189 190 191After resolving the conflict manually and updating the index with the 192desired resolution, you can continue the rebasing process with 193 194 195 git rebase --continue 196 197 198Alternatively, you can undo the 'git rebase' with 199 200 201 git rebase --abort 202 203CONFIGURATION 204------------- 205 206include::config/rebase.txt[] 207 208OPTIONS 209------- 210--onto <newbase>:: 211 Starting point at which to create the new commits. If the 212 --onto option is not specified, the starting point is 213 <upstream>. May be any valid commit, and not just an 214 existing branch name. 215+ 216As a special case, you may use "A\...B" as a shortcut for the 217merge base of A and B if there is exactly one merge base. You can 218leave out at most one of A and B, in which case it defaults to HEAD. 219 220<upstream>:: 221 Upstream branch to compare against. May be any valid commit, 222 not just an existing branch name. Defaults to the configured 223 upstream for the current branch. 224 225<branch>:: 226 Working branch; defaults to HEAD. 227 228--continue:: 229 Restart the rebasing process after having resolved a merge conflict. 230 231--abort:: 232 Abort the rebase operation and reset HEAD to the original 233 branch. If <branch> was provided when the rebase operation was 234 started, then HEAD will be reset to <branch>. Otherwise HEAD 235 will be reset to where it was when the rebase operation was 236 started. 237 238--quit:: 239 Abort the rebase operation but HEAD is not reset back to the 240 original branch. The index and working tree are also left 241 unchanged as a result. 242 243--keep-empty:: 244 Keep the commits that do not change anything from its 245 parents in the result. 246+ 247See also INCOMPATIBLE OPTIONS below. 248 249--allow-empty-message:: 250 By default, rebasing commits with an empty message will fail. 251 This option overrides that behavior, allowing commits with empty 252 messages to be rebased. 253+ 254See also INCOMPATIBLE OPTIONS below. 255 256--skip:: 257 Restart the rebasing process by skipping the current patch. 258 259--edit-todo:: 260 Edit the todo list during an interactive rebase. 261 262--show-current-patch:: 263 Show the current patch in an interactive rebase or when rebase 264 is stopped because of conflicts. This is the equivalent of 265 `git show REBASE_HEAD`. 266 267-m:: 268--merge:: 269 Use merging strategies to rebase. When the recursive (default) merge 270 strategy is used, this allows rebase to be aware of renames on the 271 upstream side. 272+ 273Note that a rebase merge works by replaying each commit from the working 274branch on top of the <upstream> branch. Because of this, when a merge 275conflict happens, the side reported as 'ours' is the so-far rebased 276series, starting with <upstream>, and 'theirs' is the working branch. In 277other words, the sides are swapped. 278+ 279See also INCOMPATIBLE OPTIONS below. 280 281-s <strategy>:: 282--strategy=<strategy>:: 283 Use the given merge strategy. 284 If there is no `-s` option 'git merge-recursive' is used 285 instead. This implies --merge. 286+ 287Because 'git rebase' replays each commit from the working branch 288on top of the <upstream> branch using the given strategy, using 289the 'ours' strategy simply empties all patches from the <branch>, 290which makes little sense. 291+ 292See also INCOMPATIBLE OPTIONS below. 293 294-X <strategy-option>:: 295--strategy-option=<strategy-option>:: 296 Pass the <strategy-option> through to the merge strategy. 297 This implies `--merge` and, if no strategy has been 298 specified, `-s recursive`. Note the reversal of 'ours' and 299 'theirs' as noted above for the `-m` option. 300+ 301See also INCOMPATIBLE OPTIONS below. 302 303-S[<keyid>]:: 304--gpg-sign[=<keyid>]:: 305 GPG-sign commits. The `keyid` argument is optional and 306 defaults to the committer identity; if specified, it must be 307 stuck to the option without a space. 308 309-q:: 310--quiet:: 311 Be quiet. Implies --no-stat. 312 313-v:: 314--verbose:: 315 Be verbose. Implies --stat. 316 317--stat:: 318 Show a diffstat of what changed upstream since the last rebase. The 319 diffstat is also controlled by the configuration option rebase.stat. 320 321-n:: 322--no-stat:: 323 Do not show a diffstat as part of the rebase process. 324 325--no-verify:: 326 This option bypasses the pre-rebase hook. See also linkgit:githooks[5]. 327 328--verify:: 329 Allows the pre-rebase hook to run, which is the default. This option can 330 be used to override --no-verify. See also linkgit:githooks[5]. 331 332-C<n>:: 333 Ensure at least <n> lines of surrounding context match before 334 and after each change. When fewer lines of surrounding 335 context exist they all must match. By default no context is 336 ever ignored. 337+ 338See also INCOMPATIBLE OPTIONS below. 339 340--no-ff:: 341--force-rebase:: 342-f:: 343 Individually replay all rebased commits instead of fast-forwarding 344 over the unchanged ones. This ensures that the entire history of 345 the rebased branch is composed of new commits. 346+ 347You may find this helpful after reverting a topic branch merge, as this option 348recreates the topic branch with fresh commits so it can be remerged 349successfully without needing to "revert the reversion" (see the 350link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for 351details). 352 353--fork-point:: 354--no-fork-point:: 355 Use reflog to find a better common ancestor between <upstream> 356 and <branch> when calculating which commits have been 357 introduced by <branch>. 358+ 359When --fork-point is active, 'fork_point' will be used instead of 360<upstream> to calculate the set of commits to rebase, where 361'fork_point' is the result of `git merge-base --fork-point <upstream> 362<branch>` command (see linkgit:git-merge-base[1]). If 'fork_point' 363ends up being empty, the <upstream> will be used as a fallback. 364+ 365If either <upstream> or --root is given on the command line, then the 366default is `--no-fork-point`, otherwise the default is `--fork-point`. 367 368--ignore-whitespace:: 369--whitespace=<option>:: 370 These flag are passed to the 'git apply' program 371 (see linkgit:git-apply[1]) that applies the patch. 372+ 373See also INCOMPATIBLE OPTIONS below. 374 375--committer-date-is-author-date:: 376--ignore-date:: 377 These flags are passed to 'git am' to easily change the dates 378 of the rebased commits (see linkgit:git-am[1]). 379+ 380See also INCOMPATIBLE OPTIONS below. 381 382--signoff:: 383 Add a Signed-off-by: trailer to all the rebased commits. Note 384 that if `--interactive` is given then only commits marked to be 385 picked, edited or reworded will have the trailer added. 386+ 387See also INCOMPATIBLE OPTIONS below. 388 389-i:: 390--interactive:: 391 Make a list of the commits which are about to be rebased. Let the 392 user edit that list before rebasing. This mode can also be used to 393 split commits (see SPLITTING COMMITS below). 394+ 395The commit list format can be changed by setting the configuration option 396rebase.instructionFormat. A customized instruction format will automatically 397have the long commit hash prepended to the format. 398+ 399See also INCOMPATIBLE OPTIONS below. 400 401-r:: 402--rebase-merges[=(rebase-cousins|no-rebase-cousins)]:: 403 By default, a rebase will simply drop merge commits from the todo 404 list, and put the rebased commits into a single, linear branch. 405 With `--rebase-merges`, the rebase will instead try to preserve 406 the branching structure within the commits that are to be rebased, 407 by recreating the merge commits. Any resolved merge conflicts or 408 manual amendments in these merge commits will have to be 409 resolved/re-applied manually. 410+ 411By default, or when `no-rebase-cousins` was specified, commits which do not 412have `<upstream>` as direct ancestor will keep their original branch point, 413i.e. commits that would be excluded by gitlink:git-log[1]'s 414`--ancestry-path` option will keep their original ancestry by default. If 415the `rebase-cousins` mode is turned on, such commits are instead rebased 416onto `<upstream>` (or `<onto>`, if specified). 417+ 418The `--rebase-merges` mode is similar in spirit to `--preserve-merges`, but 419in contrast to that option works well in interactive rebases: commits can be 420reordered, inserted and dropped at will. 421+ 422It is currently only possible to recreate the merge commits using the 423`recursive` merge strategy; Different merge strategies can be used only via 424explicit `exec git merge -s <strategy> [...]` commands. 425+ 426See also REBASING MERGES and INCOMPATIBLE OPTIONS below. 427 428-p:: 429--preserve-merges:: 430 Recreate merge commits instead of flattening the history by replaying 431 commits a merge commit introduces. Merge conflict resolutions or manual 432 amendments to merge commits are not preserved. 433+ 434This uses the `--interactive` machinery internally, but combining it 435with the `--interactive` option explicitly is generally not a good 436idea unless you know what you are doing (see BUGS below). 437+ 438See also INCOMPATIBLE OPTIONS below. 439 440-x <cmd>:: 441--exec <cmd>:: 442 Append "exec <cmd>" after each line creating a commit in the 443 final history. <cmd> will be interpreted as one or more shell 444 commands. Any command that fails will interrupt the rebase, 445 with exit code 1. 446+ 447You may execute several commands by either using one instance of `--exec` 448with several commands: 449+ 450 git rebase -i --exec "cmd1 && cmd2 && ..." 451+ 452or by giving more than one `--exec`: 453+ 454 git rebase -i --exec "cmd1" --exec "cmd2" --exec ... 455+ 456If `--autosquash` is used, "exec" lines will not be appended for 457the intermediate commits, and will only appear at the end of each 458squash/fixup series. 459+ 460This uses the `--interactive` machinery internally, but it can be run 461without an explicit `--interactive`. 462+ 463See also INCOMPATIBLE OPTIONS below. 464 465-y <cmd>:: 466 This is the same as passing `--reschedule-failed-exec` before 467 `-x <cmd>`, i.e. it appends the specified `exec` command and 468 turns on the mode where failed `exec` commands are automatically 469 rescheduled. 470 471--root:: 472 Rebase all commits reachable from <branch>, instead of 473 limiting them with an <upstream>. This allows you to rebase 474 the root commit(s) on a branch. When used with --onto, it 475 will skip changes already contained in <newbase> (instead of 476 <upstream>) whereas without --onto it will operate on every change. 477 When used together with both --onto and --preserve-merges, 478 'all' root commits will be rewritten to have <newbase> as parent 479 instead. 480+ 481See also INCOMPATIBLE OPTIONS below. 482 483--autosquash:: 484--no-autosquash:: 485 When the commit log message begins with "squash! ..." (or 486 "fixup! ..."), and there is already a commit in the todo list that 487 matches the same `...`, automatically modify the todo list of rebase 488 -i so that the commit marked for squashing comes right after the 489 commit to be modified, and change the action of the moved commit 490 from `pick` to `squash` (or `fixup`). A commit matches the `...` if 491 the commit subject matches, or if the `...` refers to the commit's 492 hash. As a fall-back, partial matches of the commit subject work, 493 too. The recommended way to create fixup/squash commits is by using 494 the `--fixup`/`--squash` options of linkgit:git-commit[1]. 495+ 496If the `--autosquash` option is enabled by default using the 497configuration variable `rebase.autoSquash`, this option can be 498used to override and disable this setting. 499+ 500See also INCOMPATIBLE OPTIONS below. 501 502--autostash:: 503--no-autostash:: 504 Automatically create a temporary stash entry before the operation 505 begins, and apply it after the operation ends. This means 506 that you can run rebase on a dirty worktree. However, use 507 with care: the final stash application after a successful 508 rebase might result in non-trivial conflicts. 509 510--reschedule-failed-exec:: 511--no-reschedule-failed-exec:: 512 Automatically reschedule `exec` commands that failed. This only makes 513 sense in interactive mode (or when an `--exec` option was provided). 514 515INCOMPATIBLE OPTIONS 516-------------------- 517 518git-rebase has many flags that are incompatible with each other, 519predominantly due to the fact that it has three different underlying 520implementations: 521 522 * one based on linkgit:git-am[1] (the default) 523 * one based on git-merge-recursive (merge backend) 524 * one based on linkgit:git-cherry-pick[1] (interactive backend) 525 526Flags only understood by the am backend: 527 528 * --committer-date-is-author-date 529 * --ignore-date 530 * --whitespace 531 * --ignore-whitespace 532 * -C 533 534Flags understood by both merge and interactive backends: 535 536 * --merge 537 * --strategy 538 * --strategy-option 539 * --allow-empty-message 540 541Flags only understood by the interactive backend: 542 543 * --[no-]autosquash 544 * --rebase-merges 545 * --preserve-merges 546 * --interactive 547 * --exec 548 * --keep-empty 549 * --autosquash 550 * --edit-todo 551 * --root when used in combination with --onto 552 553Other incompatible flag pairs: 554 555 * --preserve-merges and --interactive 556 * --preserve-merges and --signoff 557 * --preserve-merges and --rebase-merges 558 * --rebase-merges and --strategy 559 * --rebase-merges and --strategy-option 560 561BEHAVIORAL DIFFERENCES 562----------------------- 563 564There are some subtle differences how the backends behave. 565 566Empty commits 567~~~~~~~~~~~~~ 568 569The am backend drops any "empty" commits, regardless of whether the 570commit started empty (had no changes relative to its parent to 571start with) or ended empty (all changes were already applied 572upstream in other commits). 573 574The merge backend does the same. 575 576The interactive backend drops commits by default that 577started empty and halts if it hits a commit that ended up empty. 578The `--keep-empty` option exists for the interactive backend to allow 579it to keep commits that started empty. 580 581Directory rename detection 582~~~~~~~~~~~~~~~~~~~~~~~~~~ 583 584Directory rename heuristics are enabled in the merge and interactive 585backends. Due to the lack of accurate tree information, directory 586rename detection is disabled in the am backend. 587 588include::merge-strategies.txt[] 589 590NOTES 591----- 592 593You should understand the implications of using 'git rebase' on a 594repository that you share. See also RECOVERING FROM UPSTREAM REBASE 595below. 596 597When the git-rebase command is run, it will first execute a "pre-rebase" 598hook if one exists. You can use this hook to do sanity checks and 599reject the rebase if it isn't appropriate. Please see the template 600pre-rebase hook script for an example. 601 602Upon completion, <branch> will be the current branch. 603 604INTERACTIVE MODE 605---------------- 606 607Rebasing interactively means that you have a chance to edit the commits 608which are rebased. You can reorder the commits, and you can 609remove them (weeding out bad or otherwise unwanted patches). 610 611The interactive mode is meant for this type of workflow: 612 6131. have a wonderful idea 6142. hack on the code 6153. prepare a series for submission 6164. submit 617 618where point 2. consists of several instances of 619 620a) regular use 621 622 1. finish something worthy of a commit 623 2. commit 624 625b) independent fixup 626 627 1. realize that something does not work 628 2. fix that 629 3. commit it 630 631Sometimes the thing fixed in b.2. cannot be amended to the not-quite 632perfect commit it fixes, because that commit is buried deeply in a 633patch series. That is exactly what interactive rebase is for: use it 634after plenty of "a"s and "b"s, by rearranging and editing 635commits, and squashing multiple commits into one. 636 637Start it with the last commit you want to retain as-is: 638 639 git rebase -i <after-this-commit> 640 641An editor will be fired up with all the commits in your current branch 642(ignoring merge commits), which come after the given commit. You can 643reorder the commits in this list to your heart's content, and you can 644remove them. The list looks more or less like this: 645 646------------------------------------------- 647pick deadbee The oneline of this commit 648pick fa1afe1 The oneline of the next commit 649... 650------------------------------------------- 651 652The oneline descriptions are purely for your pleasure; 'git rebase' will 653not look at them but at the commit names ("deadbee" and "fa1afe1" in this 654example), so do not delete or edit the names. 655 656By replacing the command "pick" with the command "edit", you can tell 657'git rebase' to stop after applying that commit, so that you can edit 658the files and/or the commit message, amend the commit, and continue 659rebasing. 660 661To interrupt the rebase (just like an "edit" command would do, but without 662cherry-picking any commit first), use the "break" command. 663 664If you just want to edit the commit message for a commit, replace the 665command "pick" with the command "reword". 666 667To drop a commit, replace the command "pick" with "drop", or just 668delete the matching line. 669 670If you want to fold two or more commits into one, replace the command 671"pick" for the second and subsequent commits with "squash" or "fixup". 672If the commits had different authors, the folded commit will be 673attributed to the author of the first commit. The suggested commit 674message for the folded commit is the concatenation of the commit 675messages of the first commit and of those with the "squash" command, 676but omits the commit messages of commits with the "fixup" command. 677 678'git rebase' will stop when "pick" has been replaced with "edit" or 679when a command fails due to merge errors. When you are done editing 680and/or resolving conflicts you can continue with `git rebase --continue`. 681 682For example, if you want to reorder the last 5 commits, such that what 683was HEAD~4 becomes the new HEAD. To achieve that, you would call 684'git rebase' like this: 685 686---------------------- 687$ git rebase -i HEAD~5 688---------------------- 689 690And move the first patch to the end of the list. 691 692You might want to preserve merges, if you have a history like this: 693 694------------------ 695 X 696 \ 697 A---M---B 698 / 699---o---O---P---Q 700------------------ 701 702Suppose you want to rebase the side branch starting at "A" to "Q". Make 703sure that the current HEAD is "B", and call 704 705----------------------------- 706$ git rebase -i -p --onto Q O 707----------------------------- 708 709Reordering and editing commits usually creates untested intermediate 710steps. You may want to check that your history editing did not break 711anything by running a test, or at least recompiling at intermediate 712points in history by using the "exec" command (shortcut "x"). You may 713do so by creating a todo list like this one: 714 715------------------------------------------- 716pick deadbee Implement feature XXX 717fixup f1a5c00 Fix to feature XXX 718exec make 719pick c0ffeee The oneline of the next commit 720edit deadbab The oneline of the commit after 721exec cd subdir; make test 722... 723------------------------------------------- 724 725The interactive rebase will stop when a command fails (i.e. exits with 726non-0 status) to give you an opportunity to fix the problem. You can 727continue with `git rebase --continue`. 728 729The "exec" command launches the command in a shell (the one specified 730in `$SHELL`, or the default shell if `$SHELL` is not set), so you can 731use shell features (like "cd", ">", ";" ...). The command is run from 732the root of the working tree. 733 734---------------------------------- 735$ git rebase -i --exec "make test" 736---------------------------------- 737 738This command lets you check that intermediate commits are compilable. 739The todo list becomes like that: 740 741-------------------- 742pick 5928aea one 743exec make test 744pick 04d0fda two 745exec make test 746pick ba46169 three 747exec make test 748pick f4593f9 four 749exec make test 750-------------------- 751 752SPLITTING COMMITS 753----------------- 754 755In interactive mode, you can mark commits with the action "edit". However, 756this does not necessarily mean that 'git rebase' expects the result of this 757edit to be exactly one commit. Indeed, you can undo the commit, or you can 758add other commits. This can be used to split a commit into two: 759 760- Start an interactive rebase with `git rebase -i <commit>^`, where 761 <commit> is the commit you want to split. In fact, any commit range 762 will do, as long as it contains that commit. 763 764- Mark the commit you want to split with the action "edit". 765 766- When it comes to editing that commit, execute `git reset HEAD^`. The 767 effect is that the HEAD is rewound by one, and the index follows suit. 768 However, the working tree stays the same. 769 770- Now add the changes to the index that you want to have in the first 771 commit. You can use `git add` (possibly interactively) or 772 'git gui' (or both) to do that. 773 774- Commit the now-current index with whatever commit message is appropriate 775 now. 776 777- Repeat the last two steps until your working tree is clean. 778 779- Continue the rebase with `git rebase --continue`. 780 781If you are not absolutely sure that the intermediate revisions are 782consistent (they compile, pass the testsuite, etc.) you should use 783'git stash' to stash away the not-yet-committed changes 784after each commit, test, and amend the commit if fixes are necessary. 785 786 787RECOVERING FROM UPSTREAM REBASE 788------------------------------- 789 790Rebasing (or any other form of rewriting) a branch that others have 791based work on is a bad idea: anyone downstream of it is forced to 792manually fix their history. This section explains how to do the fix 793from the downstream's point of view. The real fix, however, would be 794to avoid rebasing the upstream in the first place. 795 796To illustrate, suppose you are in a situation where someone develops a 797'subsystem' branch, and you are working on a 'topic' that is dependent 798on this 'subsystem'. You might end up with a history like the 799following: 800 801------------ 802 o---o---o---o---o---o---o---o master 803 \ 804 o---o---o---o---o subsystem 805 \ 806 *---*---* topic 807------------ 808 809If 'subsystem' is rebased against 'master', the following happens: 810 811------------ 812 o---o---o---o---o---o---o---o master 813 \ \ 814 o---o---o---o---o o'--o'--o'--o'--o' subsystem 815 \ 816 *---*---* topic 817------------ 818 819If you now continue development as usual, and eventually merge 'topic' 820to 'subsystem', the commits from 'subsystem' will remain duplicated forever: 821 822------------ 823 o---o---o---o---o---o---o---o master 824 \ \ 825 o---o---o---o---o o'--o'--o'--o'--o'--M subsystem 826 \ / 827 *---*---*-..........-*--* topic 828------------ 829 830Such duplicates are generally frowned upon because they clutter up 831history, making it harder to follow. To clean things up, you need to 832transplant the commits on 'topic' to the new 'subsystem' tip, i.e., 833rebase 'topic'. This becomes a ripple effect: anyone downstream from 834'topic' is forced to rebase too, and so on! 835 836There are two kinds of fixes, discussed in the following subsections: 837 838Easy case: The changes are literally the same.:: 839 840 This happens if the 'subsystem' rebase was a simple rebase and 841 had no conflicts. 842 843Hard case: The changes are not the same.:: 844 845 This happens if the 'subsystem' rebase had conflicts, or used 846 `--interactive` to omit, edit, squash, or fixup commits; or 847 if the upstream used one of `commit --amend`, `reset`, or 848 `filter-branch`. 849 850 851The easy case 852~~~~~~~~~~~~~ 853 854Only works if the changes (patch IDs based on the diff contents) on 855'subsystem' are literally the same before and after the rebase 856'subsystem' did. 857 858In that case, the fix is easy because 'git rebase' knows to skip 859changes that are already present in the new upstream. So if you say 860(assuming you're on 'topic') 861------------ 862 $ git rebase subsystem 863------------ 864you will end up with the fixed history 865------------ 866 o---o---o---o---o---o---o---o master 867 \ 868 o'--o'--o'--o'--o' subsystem 869 \ 870 *---*---* topic 871------------ 872 873 874The hard case 875~~~~~~~~~~~~~ 876 877Things get more complicated if the 'subsystem' changes do not exactly 878correspond to the ones before the rebase. 879 880NOTE: While an "easy case recovery" sometimes appears to be successful 881 even in the hard case, it may have unintended consequences. For 882 example, a commit that was removed via `git rebase 883 --interactive` will be **resurrected**! 884 885The idea is to manually tell 'git rebase' "where the old 'subsystem' 886ended and your 'topic' began", that is, what the old merge-base 887between them was. You will have to find a way to name the last commit 888of the old 'subsystem', for example: 889 890* With the 'subsystem' reflog: after 'git fetch', the old tip of 891 'subsystem' is at `subsystem@{1}`. Subsequent fetches will 892 increase the number. (See linkgit:git-reflog[1].) 893 894* Relative to the tip of 'topic': knowing that your 'topic' has three 895 commits, the old tip of 'subsystem' must be `topic~3`. 896 897You can then transplant the old `subsystem..topic` to the new tip by 898saying (for the reflog case, and assuming you are on 'topic' already): 899------------ 900 $ git rebase --onto subsystem subsystem@{1} 901------------ 902 903The ripple effect of a "hard case" recovery is especially bad: 904'everyone' downstream from 'topic' will now have to perform a "hard 905case" recovery too! 906 907REBASING MERGES 908--------------- 909 910The interactive rebase command was originally designed to handle 911individual patch series. As such, it makes sense to exclude merge 912commits from the todo list, as the developer may have merged the 913then-current `master` while working on the branch, only to rebase 914all the commits onto `master` eventually (skipping the merge 915commits). 916 917However, there are legitimate reasons why a developer may want to 918recreate merge commits: to keep the branch structure (or "commit 919topology") when working on multiple, inter-related branches. 920 921In the following example, the developer works on a topic branch that 922refactors the way buttons are defined, and on another topic branch 923that uses that refactoring to implement a "Report a bug" button. The 924output of `git log --graph --format=%s -5` may look like this: 925 926------------ 927* Merge branch 'report-a-bug' 928|\ 929| * Add the feedback button 930* | Merge branch 'refactor-button' 931|\ \ 932| |/ 933| * Use the Button class for all buttons 934| * Extract a generic Button class from the DownloadButton one 935------------ 936 937The developer might want to rebase those commits to a newer `master` 938while keeping the branch topology, for example when the first topic 939branch is expected to be integrated into `master` much earlier than the 940second one, say, to resolve merge conflicts with changes to the 941DownloadButton class that made it into `master`. 942 943This rebase can be performed using the `--rebase-merges` option. 944It will generate a todo list looking like this: 945 946------------ 947label onto 948 949# Branch: refactor-button 950reset onto 951pick 123456 Extract a generic Button class from the DownloadButton one 952pick 654321 Use the Button class for all buttons 953label refactor-button 954 955# Branch: report-a-bug 956reset refactor-button # Use the Button class for all buttons 957pick abcdef Add the feedback button 958label report-a-bug 959 960reset onto 961merge -C a1b2c3 refactor-button # Merge 'refactor-button' 962merge -C 6f5e4d report-a-bug # Merge 'report-a-bug' 963------------ 964 965In contrast to a regular interactive rebase, there are `label`, `reset` 966and `merge` commands in addition to `pick` ones. 967 968The `label` command associates a label with the current HEAD when that 969command is executed. These labels are created as worktree-local refs 970(`refs/rewritten/<label>`) that will be deleted when the rebase 971finishes. That way, rebase operations in multiple worktrees linked to 972the same repository do not interfere with one another. If the `label` 973command fails, it is rescheduled immediately, with a helpful message how 974to proceed. 975 976The `reset` command resets the HEAD, index and worktree to the specified 977revision. It is similar to an `exec git reset --hard <label>`, but 978refuses to overwrite untracked files. If the `reset` command fails, it is 979rescheduled immediately, with a helpful message how to edit the todo list 980(this typically happens when a `reset` command was inserted into the todo 981list manually and contains a typo). 982 983The `merge` command will merge the specified revision(s) into whatever 984is HEAD at that time. With `-C <original-commit>`, the commit message of 985the specified merge commit will be used. When the `-C` is changed to 986a lower-case `-c`, the message will be opened in an editor after a 987successful merge so that the user can edit the message. 988 989If a `merge` command fails for any reason other than merge conflicts (i.e. 990when the merge operation did not even start), it is rescheduled immediately. 991 992At this time, the `merge` command will *always* use the `recursive` 993merge strategy for regular merges, and `octopus` for octopus merges, 994with no way to choose a different one. To work around 995this, an `exec` command can be used to call `git merge` explicitly, 996using the fact that the labels are worktree-local refs (the ref 997`refs/rewritten/onto` would correspond to the label `onto`, for example). 998 999Note: the first command (`label onto`) labels the revision onto which1000the commits are rebased; The name `onto` is just a convention, as a nod1001to the `--onto` option.10021003It is also possible to introduce completely new merge commits from scratch1004by adding a command of the form `merge <merge-head>`. This form will1005generate a tentative commit message and always open an editor to let the1006user edit it. This can be useful e.g. when a topic branch turns out to1007address more than a single concern and wants to be split into two or1008even more topic branches. Consider this todo list:10091010------------1011pick 192837 Switch from GNU Makefiles to CMake1012pick 5a6c7e Document the switch to CMake1013pick 918273 Fix detection of OpenSSL in CMake1014pick afbecd http: add support for TLS v1.31015pick fdbaec Fix detection of cURL in CMake on Windows1016------------10171018The one commit in this list that is not related to CMake may very well1019have been motivated by working on fixing all those bugs introduced by1020switching to CMake, but it addresses a different concern. To split this1021branch into two topic branches, the todo list could be edited like this:10221023------------1024label onto10251026pick afbecd http: add support for TLS v1.31027label tlsv1.310281029reset onto1030pick 192837 Switch from GNU Makefiles to CMake1031pick 918273 Fix detection of OpenSSL in CMake1032pick fdbaec Fix detection of cURL in CMake on Windows1033pick 5a6c7e Document the switch to CMake1034label cmake10351036reset onto1037merge tlsv1.31038merge cmake1039------------10401041BUGS1042----1043The todo list presented by `--preserve-merges --interactive` does not1044represent the topology of the revision graph. Editing commits and1045rewording their commit messages should work fine, but attempts to1046reorder commits tend to produce counterintuitive results. Use1047`--rebase-merges` in such scenarios instead.10481049For example, an attempt to rearrange1050------------10511 --- 2 --- 3 --- 4 --- 51052------------1053to1054------------10551 --- 2 --- 4 --- 3 --- 51056------------1057by moving the "pick 4" line will result in the following history:1058------------1059 31060 /10611 --- 2 --- 4 --- 51062------------10631064GIT1065---1066Part of the linkgit:git[1] suite