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1 git-rebase(1)
2 =============
3
4 NAME
5 ----
6 git-rebase - Reapply commits on top of another base tip
7
8 SYNOPSIS
9 --------
10 [verse]
11 'git rebase' [-i | --interactive] [<options>] [--exec <cmd>]
12 [--onto <newbase> | --keep-base] [<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
17 DESCRIPTION
18 -----------
19 If `<branch>` is specified, `git rebase` will perform an automatic
20 `git switch <branch>` before doing anything else. Otherwise
21 it remains on the current branch.
22
23 If `<upstream>` is not specified, the upstream configured in
24 `branch.<name>.remote` and `branch.<name>.merge` options will be used (see
25 linkgit:git-config[1] for details) and the `--fork-point` option is
26 assumed. If you are currently not on any branch or if the current
27 branch does not have a configured upstream, the rebase will abort.
28
29 All changes made by commits in the current branch but that are not
30 in `<upstream>` are saved to a temporary area. This is the same set
31 of 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
33 description on `--fork-point` below); or by `git log HEAD`, if the
34 `--root` option is specified.
35
36 The 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
39 to point at the tip of the branch before the reset.
40
41 The commits that were previously saved into the temporary area are
42 then reapplied to the current branch, one by one, in order. Note that
43 any commits in `HEAD` which introduce the same textual changes as a commit
44 in `HEAD..<upstream>` are omitted (i.e., a patch already accepted upstream
45 with a different commit message or timestamp will be skipped).
46
47 It is possible that a merge failure will prevent this process from being
48 completely automatic. You will have to resolve any such merge failure
49 and run `git rebase --continue`. Another option is to bypass the commit
50 that caused the merge failure with `git rebase --skip`. To check out the
51 original `<branch>` and remove the `.git/rebase-apply` working files, use
52 the command `git rebase --abort` instead.
53
54 Assume 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
62 From this point, the result of either of the following commands:
63
64
65 git rebase master
66 git rebase master topic
67
68 would 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`
77 followed by `git rebase master`. When rebase exits `topic` will
78 remain the checked-out branch.
79
80 If the upstream branch already contains a change you have made (e.g.,
81 because you mailed a patch which was applied upstream), then that commit
82 will be skipped and warnings will be issued (if the 'merge' backend is
83 used). For example, running `git rebase master` on the following
84 history (in which `A'` and `A` introduce the same set of changes, but
85 have different committer information):
86
87 ------------
88 A---B---C topic
89 /
90 D---E---A'---F master
91 ------------
92
93 will result in:
94
95 ------------
96 B'---C' topic
97 /
98 D---E---A'---F master
99 ------------
100
101 Here is how you would transplant a topic branch based on one
102 branch to another, to pretend that you forked the topic branch
103 from the latter branch, using `rebase --onto`.
104
105 First let's assume your 'topic' is based on branch 'next'.
106 For example, a feature developed in 'topic' depends on some
107 functionality which is found in 'next'.
108
109 ------------
110 o---o---o---o---o master
111 \
112 o---o---o---o---o next
113 \
114 o---o---o topic
115 ------------
116
117 We want to make 'topic' forked from branch 'master'; for example,
118 because the functionality on which 'topic' depends was merged into the
119 more stable 'master' branch. We want our tree to look like this:
120
121 ------------
122 o---o---o---o---o master
123 | \
124 | o'--o'--o' topic
125 \
126 o---o---o---o---o next
127 ------------
128
129 We can get this using the following command:
130
131 git rebase --onto master next topic
132
133
134 Another example of --onto option is to rebase part of a
135 branch. If we have the following situation:
136
137 ------------
138 H---I---J topicB
139 /
140 E---F---G topicA
141 /
142 A---B---C---D master
143 ------------
144
145 then the command
146
147 git rebase --onto master topicA topicB
148
149 would result in:
150
151 ------------
152 H'--I'--J' topicB
153 /
154 | E---F---G topicA
155 |/
156 A---B---C---D master
157 ------------
158
159 This is useful when topicB does not depend on topicA.
160
161 A range of commits could also be removed with rebase. If we have
162 the following situation:
163
164 ------------
165 E---F---G---H---I---J topicA
166 ------------
167
168 then the command
169
170 git rebase --onto topicA~5 topicA~3 topicA
171
172 would result in the removal of commits F and G:
173
174 ------------
175 E---H'---I'---J' topicA
176 ------------
177
178 This is useful if F and G were flawed in some way, or should not be
179 part of topicA. Note that the argument to `--onto` and the `<upstream>`
180 parameter can be any valid commit-ish.
181
182 In case of conflict, `git rebase` will stop at the first problematic commit
183 and leave conflict markers in the tree. You can use `git diff` to locate
184 the markers (<<<<<<) and make edits to resolve the conflict. For each
185 file you edit, you need to tell Git that the conflict has been resolved,
186 typically this would be done with
187
188
189 git add <filename>
190
191
192 After resolving the conflict manually and updating the index with the
193 desired resolution, you can continue the rebasing process with
194
195
196 git rebase --continue
197
198
199 Alternatively, you can undo the 'git rebase' with
200
201
202 git rebase --abort
203
204 OPTIONS
205 -------
206 --onto <newbase>::
207 Starting point at which to create the new commits. If the
208 `--onto` option is not specified, the starting point is
209 `<upstream>`. May be any valid commit, and not just an
210 existing branch name.
211 +
212 As a special case, you may use "A\...B" as a shortcut for the
213 merge base of A and B if there is exactly one merge base. You can
214 leave out at most one of A and B, in which case it defaults to HEAD.
215
216 --keep-base::
217 Set the starting point at which to create the new commits to the
218 merge base of `<upstream>` and `<branch>`. Running
219 `git rebase --keep-base <upstream> <branch>` is equivalent to
220 running
221 `git rebase --onto <upstream>...<branch> <upstream> <branch>`.
222 +
223 This option is useful in the case where one is developing a feature on
224 top of an upstream branch. While the feature is being worked on, the
225 upstream branch may advance and it may not be the best idea to keep
226 rebasing on top of the upstream but to keep the base commit as-is.
227 +
228 Although both this option and `--fork-point` find the merge base between
229 `<upstream>` and `<branch>`, this option uses the merge base as the _starting
230 point_ on which new commits will be created, whereas `--fork-point` uses
231 the merge base to determine the _set of commits_ which will be rebased.
232 +
233 See also INCOMPATIBLE OPTIONS below.
234
235 <upstream>::
236 Upstream branch to compare against. May be any valid commit,
237 not just an existing branch name. Defaults to the configured
238 upstream for the current branch.
239
240 <branch>::
241 Working branch; defaults to `HEAD`.
242
243 --continue::
244 Restart the rebasing process after having resolved a merge conflict.
245
246 --abort::
247 Abort the rebase operation and reset HEAD to the original
248 branch. If `<branch>` was provided when the rebase operation was
249 started, then `HEAD` will be reset to `<branch>`. Otherwise `HEAD`
250 will be reset to where it was when the rebase operation was
251 started.
252
253 --quit::
254 Abort the rebase operation but `HEAD` is not reset back to the
255 original branch. The index and working tree are also left
256 unchanged as a result. If a temporary stash entry was created
257 using `--autostash`, it will be saved to the stash list.
258
259 --apply::
260 Use applying strategies to rebase (calling `git-am`
261 internally). This option may become a no-op in the future
262 once the merge backend handles everything the apply one does.
263 +
264 See also INCOMPATIBLE OPTIONS below.
265
266 --empty={drop,keep,ask}::
267 How to handle commits that are not empty to start and are not
268 clean cherry-picks of any upstream commit, but which become
269 empty after rebasing (because they contain a subset of already
270 upstream changes). With drop (the default), commits that
271 become empty are dropped. With keep, such commits are kept.
272 With ask (implied by `--interactive`), the rebase will halt when
273 an empty commit is applied allowing you to choose whether to
274 drop it, edit files more, or just commit the empty changes.
275 Other options, like `--exec`, will use the default of drop unless
276 `-i`/`--interactive` is explicitly specified.
277 +
278 Note that commits which start empty are kept (unless `--no-keep-empty`
279 is specified), and commits which are clean cherry-picks (as determined
280 by `git log --cherry-mark ...`) are detected and dropped as a
281 preliminary step (unless `--reapply-cherry-picks` is passed).
282 +
283 See also INCOMPATIBLE OPTIONS below.
284
285 --no-keep-empty::
286 --keep-empty::
287 Do not keep commits that start empty before the rebase
288 (i.e. that do not change anything from its parent) in the
289 result. The default is to keep commits which start empty,
290 since creating such commits requires passing the `--allow-empty`
291 override flag to `git commit`, signifying that a user is very
292 intentionally creating such a commit and thus wants to keep
293 it.
294 +
295 Usage of this flag will probably be rare, since you can get rid of
296 commits that start empty by just firing up an interactive rebase and
297 removing the lines corresponding to the commits you don't want. This
298 flag exists as a convenient shortcut, such as for cases where external
299 tools generate many empty commits and you want them all removed.
300 +
301 For commits which do not start empty but become empty after rebasing,
302 see the `--empty` flag.
303 +
304 See also INCOMPATIBLE OPTIONS below.
305
306 --reapply-cherry-picks::
307 --no-reapply-cherry-picks::
308 Reapply all clean cherry-picks of any upstream commit instead
309 of preemptively dropping them. (If these commits then become
310 empty after rebasing, because they contain a subset of already
311 upstream changes, the behavior towards them is controlled by
312 the `--empty` flag.)
313 +
314 By default (or if `--no-reapply-cherry-picks` is given), these commits
315 will be automatically dropped. Because this necessitates reading all
316 upstream commits, this can be expensive in repos with a large number
317 of upstream commits that need to be read. When using the 'merge'
318 backend, warnings will be issued for each dropped commit (unless
319 `--quiet` is given). Advice will also be issued unless
320 `advice.skippedCherryPicks` is set to false (see linkgit:git-config[1]).
321 +
322 `--reapply-cherry-picks` allows rebase to forgo reading all upstream
323 commits, potentially improving performance.
324 +
325 See also INCOMPATIBLE OPTIONS below.
326
327 --allow-empty-message::
328 No-op. Rebasing commits with an empty message used to fail
329 and this option would override that behavior, allowing commits
330 with empty messages to be rebased. Now commits with an empty
331 message do not cause rebasing to halt.
332 +
333 See also INCOMPATIBLE OPTIONS below.
334
335 --skip::
336 Restart the rebasing process by skipping the current patch.
337
338 --edit-todo::
339 Edit the todo list during an interactive rebase.
340
341 --show-current-patch::
342 Show the current patch in an interactive rebase or when rebase
343 is stopped because of conflicts. This is the equivalent of
344 `git show REBASE_HEAD`.
345
346 -m::
347 --merge::
348 Using merging strategies to rebase (default).
349 +
350 Note that a rebase merge works by replaying each commit from the working
351 branch on top of the `<upstream>` branch. Because of this, when a merge
352 conflict happens, the side reported as 'ours' is the so-far rebased
353 series, starting with `<upstream>`, and 'theirs' is the working branch.
354 In other words, the sides are swapped.
355 +
356 See also INCOMPATIBLE OPTIONS below.
357
358 -s <strategy>::
359 --strategy=<strategy>::
360 Use the given merge strategy, instead of the default `ort`.
361 This implies `--merge`.
362 +
363 Because `git rebase` replays each commit from the working branch
364 on top of the `<upstream>` branch using the given strategy, using
365 the `ours` strategy simply empties all patches from the `<branch>`,
366 which makes little sense.
367 +
368 See also INCOMPATIBLE OPTIONS below.
369
370 -X <strategy-option>::
371 --strategy-option=<strategy-option>::
372 Pass the <strategy-option> through to the merge strategy.
373 This implies `--merge` and, if no strategy has been
374 specified, `-s ort`. Note the reversal of 'ours' and
375 'theirs' as noted above for the `-m` option.
376 +
377 See also INCOMPATIBLE OPTIONS below.
378
379 --rerere-autoupdate::
380 --no-rerere-autoupdate::
381 Allow the rerere mechanism to update the index with the
382 result of auto-conflict resolution if possible.
383
384 -S[<keyid>]::
385 --gpg-sign[=<keyid>]::
386 --no-gpg-sign::
387 GPG-sign commits. The `keyid` argument is optional and
388 defaults to the committer identity; if specified, it must be
389 stuck to the option without a space. `--no-gpg-sign` is useful to
390 countermand both `commit.gpgSign` configuration variable, and
391 earlier `--gpg-sign`.
392
393 -q::
394 --quiet::
395 Be quiet. Implies `--no-stat`.
396
397 -v::
398 --verbose::
399 Be verbose. Implies `--stat`.
400
401 --stat::
402 Show a diffstat of what changed upstream since the last rebase. The
403 diffstat is also controlled by the configuration option rebase.stat.
404
405 -n::
406 --no-stat::
407 Do not show a diffstat as part of the rebase process.
408
409 --no-verify::
410 This option bypasses the pre-rebase hook. See also linkgit:githooks[5].
411
412 --verify::
413 Allows the pre-rebase hook to run, which is the default. This option can
414 be used to override `--no-verify`. See also linkgit:githooks[5].
415
416 -C<n>::
417 Ensure at least `<n>` lines of surrounding context match before
418 and after each change. When fewer lines of surrounding
419 context exist they all must match. By default no context is
420 ever ignored. Implies `--apply`.
421 +
422 See also INCOMPATIBLE OPTIONS below.
423
424 --no-ff::
425 --force-rebase::
426 -f::
427 Individually replay all rebased commits instead of fast-forwarding
428 over the unchanged ones. This ensures that the entire history of
429 the rebased branch is composed of new commits.
430 +
431 You may find this helpful after reverting a topic branch merge, as this option
432 recreates the topic branch with fresh commits so it can be remerged
433 successfully without needing to "revert the reversion" (see the
434 link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for
435 details).
436
437 --fork-point::
438 --no-fork-point::
439 Use reflog to find a better common ancestor between `<upstream>`
440 and `<branch>` when calculating which commits have been
441 introduced by `<branch>`.
442 +
443 When `--fork-point` is active, 'fork_point' will be used instead of
444 `<upstream>` to calculate the set of commits to rebase, where
445 'fork_point' is the result of `git merge-base --fork-point <upstream>
446 <branch>` command (see linkgit:git-merge-base[1]). If 'fork_point'
447 ends up being empty, the `<upstream>` will be used as a fallback.
448 +
449 If `<upstream>` is given on the command line, then the default is
450 `--no-fork-point`, otherwise the default is `--fork-point`. See also
451 `rebase.forkpoint` in linkgit:git-config[1].
452 +
453 If your branch was based on `<upstream>` but `<upstream>` was rewound and
454 your branch contains commits which were dropped, this option can be used
455 with `--keep-base` in order to drop those commits from your branch.
456 +
457 See also INCOMPATIBLE OPTIONS below.
458
459 --ignore-whitespace::
460 Ignore whitespace differences when trying to reconcile
461 differences. Currently, each backend implements an approximation of
462 this behavior:
463 +
464 apply backend;;
465 When applying a patch, ignore changes in whitespace in context
466 lines. Unfortunately, this means that if the "old" lines being
467 replaced by the patch differ only in whitespace from the existing
468 file, you will get a merge conflict instead of a successful patch
469 application.
470 +
471 merge backend;;
472 Treat lines with only whitespace changes as unchanged when merging.
473 Unfortunately, this means that any patch hunks that were intended
474 to modify whitespace and nothing else will be dropped, even if the
475 other side had no changes that conflicted.
476
477 --whitespace=<option>::
478 This flag is passed to the `git apply` program
479 (see linkgit:git-apply[1]) that applies the patch.
480 Implies `--apply`.
481 +
482 See also INCOMPATIBLE OPTIONS below.
483
484 --committer-date-is-author-date::
485 Instead of using the current time as the committer date, use
486 the author date of the commit being rebased as the committer
487 date. This option implies `--force-rebase`.
488
489 --ignore-date::
490 --reset-author-date::
491 Instead of using the author date of the original commit, use
492 the current time as the author date of the rebased commit. This
493 option implies `--force-rebase`.
494 +
495 See also INCOMPATIBLE OPTIONS below.
496
497 --signoff::
498 Add a `Signed-off-by` trailer to all the rebased commits. Note
499 that if `--interactive` is given then only commits marked to be
500 picked, edited or reworded will have the trailer added.
501 +
502 See also INCOMPATIBLE OPTIONS below.
503
504 -i::
505 --interactive::
506 Make a list of the commits which are about to be rebased. Let the
507 user edit that list before rebasing. This mode can also be used to
508 split commits (see SPLITTING COMMITS below).
509 +
510 The commit list format can be changed by setting the configuration option
511 rebase.instructionFormat. A customized instruction format will automatically
512 have the long commit hash prepended to the format.
513 +
514 See also INCOMPATIBLE OPTIONS below.
515
516 -r::
517 --rebase-merges[=(rebase-cousins|no-rebase-cousins)]::
518 By default, a rebase will simply drop merge commits from the todo
519 list, and put the rebased commits into a single, linear branch.
520 With `--rebase-merges`, the rebase will instead try to preserve
521 the branching structure within the commits that are to be rebased,
522 by recreating the merge commits. Any resolved merge conflicts or
523 manual amendments in these merge commits will have to be
524 resolved/re-applied manually.
525 +
526 By default, or when `no-rebase-cousins` was specified, commits which do not
527 have `<upstream>` as direct ancestor will keep their original branch point,
528 i.e. commits that would be excluded by linkgit:git-log[1]'s
529 `--ancestry-path` option will keep their original ancestry by default. If
530 the `rebase-cousins` mode is turned on, such commits are instead rebased
531 onto `<upstream>` (or `<onto>`, if specified).
532 +
533 It is currently only possible to recreate the merge commits using the
534 `ort` merge strategy; different merge strategies can be used only via
535 explicit `exec git merge -s <strategy> [...]` commands.
536 +
537 See also REBASING MERGES and INCOMPATIBLE OPTIONS below.
538
539 -x <cmd>::
540 --exec <cmd>::
541 Append "exec <cmd>" after each line creating a commit in the
542 final history. `<cmd>` will be interpreted as one or more shell
543 commands. Any command that fails will interrupt the rebase,
544 with exit code 1.
545 +
546 You may execute several commands by either using one instance of `--exec`
547 with several commands:
548 +
549 git rebase -i --exec "cmd1 && cmd2 && ..."
550 +
551 or by giving more than one `--exec`:
552 +
553 git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
554 +
555 If `--autosquash` is used, `exec` lines will not be appended for
556 the intermediate commits, and will only appear at the end of each
557 squash/fixup series.
558 +
559 This uses the `--interactive` machinery internally, but it can be run
560 without an explicit `--interactive`.
561 +
562 See also INCOMPATIBLE OPTIONS below.
563
564 --root::
565 Rebase all commits reachable from `<branch>`, instead of
566 limiting them with an `<upstream>`. This allows you to rebase
567 the root commit(s) on a branch. When used with `--onto`, it
568 will skip changes already contained in `<newbase>` (instead of
569 `<upstream>`) whereas without `--onto` it will operate on every
570 change.
571 +
572 See also INCOMPATIBLE OPTIONS below.
573
574 --autosquash::
575 --no-autosquash::
576 When the commit log message begins with "squash! ..." or "fixup! ..."
577 or "amend! ...", and there is already a commit in the todo list that
578 matches the same `...`, automatically modify the todo list of
579 `rebase -i`, so that the commit marked for squashing comes right after
580 the commit to be modified, and change the action of the moved commit
581 from `pick` to `squash` or `fixup` or `fixup -C` respectively. A commit
582 matches the `...` if the commit subject matches, or if the `...` refers
583 to the commit's hash. As a fall-back, partial matches of the commit
584 subject work, too. The recommended way to create fixup/amend/squash
585 commits is by using the `--fixup`, `--fixup=amend:` or `--fixup=reword:`
586 and `--squash` options respectively of linkgit:git-commit[1].
587 +
588 If the `--autosquash` option is enabled by default using the
589 configuration variable `rebase.autoSquash`, this option can be
590 used to override and disable this setting.
591 +
592 See also INCOMPATIBLE OPTIONS below.
593
594 --autostash::
595 --no-autostash::
596 Automatically create a temporary stash entry before the operation
597 begins, and apply it after the operation ends. This means
598 that you can run rebase on a dirty worktree. However, use
599 with care: the final stash application after a successful
600 rebase might result in non-trivial conflicts.
601
602 --reschedule-failed-exec::
603 --no-reschedule-failed-exec::
604 Automatically reschedule `exec` commands that failed. This only makes
605 sense in interactive mode (or when an `--exec` option was provided).
606 +
607 Even though this option applies once a rebase is started, it's set for
608 the whole rebase at the start based on either the
609 `rebase.rescheduleFailedExec` configuration (see linkgit:git-config[1]
610 or "CONFIGURATION" below) or whether this option is
611 provided. Otherwise an explicit `--no-reschedule-failed-exec` at the
612 start would be overridden by the presence of
613 `rebase.rescheduleFailedExec=true` configuration.
614
615 INCOMPATIBLE OPTIONS
616 --------------------
617
618 The following options:
619
620 * --apply
621 * --whitespace
622 * -C
623
624 are incompatible with the following options:
625
626 * --merge
627 * --strategy
628 * --strategy-option
629 * --allow-empty-message
630 * --[no-]autosquash
631 * --rebase-merges
632 * --interactive
633 * --exec
634 * --no-keep-empty
635 * --empty=
636 * --reapply-cherry-picks
637 * --edit-todo
638 * --root when used in combination with --onto
639
640 In addition, the following pairs of options are incompatible:
641
642 * --keep-base and --onto
643 * --keep-base and --root
644 * --fork-point and --root
645
646 BEHAVIORAL DIFFERENCES
647 -----------------------
648
649 `git rebase` has two primary backends: 'apply' and 'merge'. (The 'apply'
650 backend used to be known as the 'am' backend, but the name led to
651 confusion as it looks like a verb instead of a noun. Also, the 'merge'
652 backend used to be known as the interactive backend, but it is now
653 used for non-interactive cases as well. Both were renamed based on
654 lower-level functionality that underpinned each.) There are some
655 subtle differences in how these two backends behave:
656
657 Empty commits
658 ~~~~~~~~~~~~~
659
660 The 'apply' backend unfortunately drops intentionally empty commits, i.e.
661 commits that started empty, though these are rare in practice. It
662 also drops commits that become empty and has no option for controlling
663 this behavior.
664
665 The 'merge' backend keeps intentionally empty commits by default (though
666 with `-i` they are marked as empty in the todo list editor, or they can
667 be dropped automatically with `--no-keep-empty`).
668
669 Similar to the apply backend, by default the merge backend drops
670 commits that become empty unless `-i`/`--interactive` is specified (in
671 which case it stops and asks the user what to do). The merge backend
672 also has an `--empty={drop,keep,ask}` option for changing the behavior
673 of handling commits that become empty.
674
675 Directory rename detection
676 ~~~~~~~~~~~~~~~~~~~~~~~~~~
677
678 Due to the lack of accurate tree information (arising from
679 constructing fake ancestors with the limited information available in
680 patches), directory rename detection is disabled in the 'apply' backend.
681 Disabled directory rename detection means that if one side of history
682 renames a directory and the other adds new files to the old directory,
683 then the new files will be left behind in the old directory without
684 any warning at the time of rebasing that you may want to move these
685 files into the new directory.
686
687 Directory rename detection works with the 'merge' backend to provide you
688 warnings in such cases.
689
690 Context
691 ~~~~~~~
692
693 The 'apply' backend works by creating a sequence of patches (by calling
694 `format-patch` internally), and then applying the patches in sequence
695 (calling `am` internally). Patches are composed of multiple hunks,
696 each with line numbers, a context region, and the actual changes. The
697 line numbers have to be taken with some fuzz, since the other side
698 will likely have inserted or deleted lines earlier in the file. The
699 context region is meant to help find how to adjust the line numbers in
700 order to apply the changes to the right lines. However, if multiple
701 areas of the code have the same surrounding lines of context, the
702 wrong one can be picked. There are real-world cases where this has
703 caused commits to be reapplied incorrectly with no conflicts reported.
704 Setting `diff.context` to a larger value may prevent such types of
705 problems, but increases the chance of spurious conflicts (since it
706 will require more lines of matching context to apply).
707
708 The 'merge' backend works with a full copy of each relevant file,
709 insulating it from these types of problems.
710
711 Labelling of conflicts markers
712 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
713
714 When there are content conflicts, the merge machinery tries to
715 annotate each side's conflict markers with the commits where the
716 content came from. Since the 'apply' backend drops the original
717 information about the rebased commits and their parents (and instead
718 generates new fake commits based off limited information in the
719 generated patches), those commits cannot be identified; instead it has
720 to fall back to a commit summary. Also, when `merge.conflictStyle` is
721 set to `diff3` or `zdiff3`, the 'apply' backend will use "constructed merge
722 base" to label the content from the merge base, and thus provide no
723 information about the merge base commit whatsoever.
724
725 The 'merge' backend works with the full commits on both sides of history
726 and thus has no such limitations.
727
728 Hooks
729 ~~~~~
730
731 The 'apply' backend has not traditionally called the post-commit hook,
732 while the 'merge' backend has. Both have called the post-checkout hook,
733 though the 'merge' backend has squelched its output. Further, both
734 backends only call the post-checkout hook with the starting point
735 commit of the rebase, not the intermediate commits nor the final
736 commit. In each case, the calling of these hooks was by accident of
737 implementation rather than by design (both backends were originally
738 implemented as shell scripts and happened to invoke other commands
739 like `git checkout` or `git commit` that would call the hooks). Both
740 backends should have the same behavior, though it is not entirely
741 clear which, if any, is correct. We will likely make rebase stop
742 calling either of these hooks in the future.
743
744 Interruptability
745 ~~~~~~~~~~~~~~~~
746
747 The 'apply' backend has safety problems with an ill-timed interrupt; if
748 the user presses Ctrl-C at the wrong time to try to abort the rebase,
749 the rebase can enter a state where it cannot be aborted with a
750 subsequent `git rebase --abort`. The 'merge' backend does not appear to
751 suffer from the same shortcoming. (See
752 https://lore.kernel.org/git/20200207132152.GC2868@szeder.dev/ for
753 details.)
754
755 Commit Rewording
756 ~~~~~~~~~~~~~~~~
757
758 When a conflict occurs while rebasing, rebase stops and asks the user
759 to resolve. Since the user may need to make notable changes while
760 resolving conflicts, after conflicts are resolved and the user has run
761 `git rebase --continue`, the rebase should open an editor and ask the
762 user to update the commit message. The 'merge' backend does this, while
763 the 'apply' backend blindly applies the original commit message.
764
765 Miscellaneous differences
766 ~~~~~~~~~~~~~~~~~~~~~~~~~
767
768 There are a few more behavioral differences that most folks would
769 probably consider inconsequential but which are mentioned for
770 completeness:
771
772 * Reflog: The two backends will use different wording when describing
773 the changes made in the reflog, though both will make use of the
774 word "rebase".
775
776 * Progress, informational, and error messages: The two backends
777 provide slightly different progress and informational messages.
778 Also, the apply backend writes error messages (such as "Your files
779 would be overwritten...") to stdout, while the merge backend writes
780 them to stderr.
781
782 * State directories: The two backends keep their state in different
783 directories under `.git/`
784
785 include::merge-strategies.txt[]
786
787 NOTES
788 -----
789
790 You should understand the implications of using `git rebase` on a
791 repository that you share. See also RECOVERING FROM UPSTREAM REBASE
792 below.
793
794 When the rebase is run, it will first execute a `pre-rebase` hook if one
795 exists. You can use this hook to do sanity checks and reject the rebase
796 if it isn't appropriate. Please see the template `pre-rebase` hook script
797 for an example.
798
799 Upon completion, `<branch>` will be the current branch.
800
801 INTERACTIVE MODE
802 ----------------
803
804 Rebasing interactively means that you have a chance to edit the commits
805 which are rebased. You can reorder the commits, and you can
806 remove them (weeding out bad or otherwise unwanted patches).
807
808 The interactive mode is meant for this type of workflow:
809
810 1. have a wonderful idea
811 2. hack on the code
812 3. prepare a series for submission
813 4. submit
814
815 where point 2. consists of several instances of
816
817 a) regular use
818
819 1. finish something worthy of a commit
820 2. commit
821
822 b) independent fixup
823
824 1. realize that something does not work
825 2. fix that
826 3. commit it
827
828 Sometimes the thing fixed in b.2. cannot be amended to the not-quite
829 perfect commit it fixes, because that commit is buried deeply in a
830 patch series. That is exactly what interactive rebase is for: use it
831 after plenty of "a"s and "b"s, by rearranging and editing
832 commits, and squashing multiple commits into one.
833
834 Start it with the last commit you want to retain as-is:
835
836 git rebase -i <after-this-commit>
837
838 An editor will be fired up with all the commits in your current branch
839 (ignoring merge commits), which come after the given commit. You can
840 reorder the commits in this list to your heart's content, and you can
841 remove them. The list looks more or less like this:
842
843 -------------------------------------------
844 pick deadbee The oneline of this commit
845 pick fa1afe1 The oneline of the next commit
846 ...
847 -------------------------------------------
848
849 The oneline descriptions are purely for your pleasure; 'git rebase' will
850 not look at them but at the commit names ("deadbee" and "fa1afe1" in this
851 example), so do not delete or edit the names.
852
853 By replacing the command "pick" with the command "edit", you can tell
854 `git rebase` to stop after applying that commit, so that you can edit
855 the files and/or the commit message, amend the commit, and continue
856 rebasing.
857
858 To interrupt the rebase (just like an "edit" command would do, but without
859 cherry-picking any commit first), use the "break" command.
860
861 If you just want to edit the commit message for a commit, replace the
862 command "pick" with the command "reword".
863
864 To drop a commit, replace the command "pick" with "drop", or just
865 delete the matching line.
866
867 If you want to fold two or more commits into one, replace the command
868 "pick" for the second and subsequent commits with "squash" or "fixup".
869 If the commits had different authors, the folded commit will be
870 attributed to the author of the first commit. The suggested commit
871 message for the folded commit is the concatenation of the first
872 commit's message with those identified by "squash" commands, omitting the
873 messages of commits identified by "fixup" commands, unless "fixup -c"
874 is used. In that case the suggested commit message is only the message
875 of the "fixup -c" commit, and an editor is opened allowing you to edit
876 the message. The contents (patch) of the "fixup -c" commit are still
877 incorporated into the folded commit. If there is more than one "fixup -c"
878 commit, the message from the final one is used. You can also use
879 "fixup -C" to get the same behavior as "fixup -c" except without opening
880 an editor.
881
882 `git rebase` will stop when "pick" has been replaced with "edit" or
883 when a command fails due to merge errors. When you are done editing
884 and/or resolving conflicts you can continue with `git rebase --continue`.
885
886 For example, if you want to reorder the last 5 commits, such that what
887 was `HEAD~4` becomes the new `HEAD`. To achieve that, you would call
888 `git rebase` like this:
889
890 ----------------------
891 $ git rebase -i HEAD~5
892 ----------------------
893
894 And move the first patch to the end of the list.
895
896 You might want to recreate merge commits, e.g. if you have a history
897 like this:
898
899 ------------------
900 X
901 \
902 A---M---B
903 /
904 ---o---O---P---Q
905 ------------------
906
907 Suppose you want to rebase the side branch starting at "A" to "Q". Make
908 sure that the current `HEAD` is "B", and call
909
910 -----------------------------
911 $ git rebase -i -r --onto Q O
912 -----------------------------
913
914 Reordering and editing commits usually creates untested intermediate
915 steps. You may want to check that your history editing did not break
916 anything by running a test, or at least recompiling at intermediate
917 points in history by using the "exec" command (shortcut "x"). You may
918 do so by creating a todo list like this one:
919
920 -------------------------------------------
921 pick deadbee Implement feature XXX
922 fixup f1a5c00 Fix to feature XXX
923 exec make
924 pick c0ffeee The oneline of the next commit
925 edit deadbab The oneline of the commit after
926 exec cd subdir; make test
927 ...
928 -------------------------------------------
929
930 The interactive rebase will stop when a command fails (i.e. exits with
931 non-0 status) to give you an opportunity to fix the problem. You can
932 continue with `git rebase --continue`.
933
934 The "exec" command launches the command in a shell (the one specified
935 in `$SHELL`, or the default shell if `$SHELL` is not set), so you can
936 use shell features (like "cd", ">", ";" ...). The command is run from
937 the root of the working tree.
938
939 ----------------------------------
940 $ git rebase -i --exec "make test"
941 ----------------------------------
942
943 This command lets you check that intermediate commits are compilable.
944 The todo list becomes like that:
945
946 --------------------
947 pick 5928aea one
948 exec make test
949 pick 04d0fda two
950 exec make test
951 pick ba46169 three
952 exec make test
953 pick f4593f9 four
954 exec make test
955 --------------------
956
957 SPLITTING COMMITS
958 -----------------
959
960 In interactive mode, you can mark commits with the action "edit". However,
961 this does not necessarily mean that `git rebase` expects the result of this
962 edit to be exactly one commit. Indeed, you can undo the commit, or you can
963 add other commits. This can be used to split a commit into two:
964
965 - Start an interactive rebase with `git rebase -i <commit>^`, where
966 `<commit>` is the commit you want to split. In fact, any commit range
967 will do, as long as it contains that commit.
968
969 - Mark the commit you want to split with the action "edit".
970
971 - When it comes to editing that commit, execute `git reset HEAD^`. The
972 effect is that the `HEAD` is rewound by one, and the index follows suit.
973 However, the working tree stays the same.
974
975 - Now add the changes to the index that you want to have in the first
976 commit. You can use `git add` (possibly interactively) or
977 `git gui` (or both) to do that.
978
979 - Commit the now-current index with whatever commit message is appropriate
980 now.
981
982 - Repeat the last two steps until your working tree is clean.
983
984 - Continue the rebase with `git rebase --continue`.
985
986 If you are not absolutely sure that the intermediate revisions are
987 consistent (they compile, pass the testsuite, etc.) you should use
988 `git stash` to stash away the not-yet-committed changes
989 after each commit, test, and amend the commit if fixes are necessary.
990
991
992 RECOVERING FROM UPSTREAM REBASE
993 -------------------------------
994
995 Rebasing (or any other form of rewriting) a branch that others have
996 based work on is a bad idea: anyone downstream of it is forced to
997 manually fix their history. This section explains how to do the fix
998 from the downstream's point of view. The real fix, however, would be
999 to avoid rebasing the upstream in the first place.
1000
1001 To illustrate, suppose you are in a situation where someone develops a
1002 'subsystem' branch, and you are working on a 'topic' that is dependent
1003 on this 'subsystem'. You might end up with a history like the
1004 following:
1005
1006 ------------
1007 o---o---o---o---o---o---o---o master
1008 \
1009 o---o---o---o---o subsystem
1010 \
1011 *---*---* topic
1012 ------------
1013
1014 If 'subsystem' is rebased against 'master', the following happens:
1015
1016 ------------
1017 o---o---o---o---o---o---o---o master
1018 \ \
1019 o---o---o---o---o o'--o'--o'--o'--o' subsystem
1020 \
1021 *---*---* topic
1022 ------------
1023
1024 If you now continue development as usual, and eventually merge 'topic'
1025 to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
1026
1027 ------------
1028 o---o---o---o---o---o---o---o master
1029 \ \
1030 o---o---o---o---o o'--o'--o'--o'--o'--M subsystem
1031 \ /
1032 *---*---*-..........-*--* topic
1033 ------------
1034
1035 Such duplicates are generally frowned upon because they clutter up
1036 history, making it harder to follow. To clean things up, you need to
1037 transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
1038 rebase 'topic'. This becomes a ripple effect: anyone downstream from
1039 'topic' is forced to rebase too, and so on!
1040
1041 There are two kinds of fixes, discussed in the following subsections:
1042
1043 Easy case: The changes are literally the same.::
1044
1045 This happens if the 'subsystem' rebase was a simple rebase and
1046 had no conflicts.
1047
1048 Hard case: The changes are not the same.::
1049
1050 This happens if the 'subsystem' rebase had conflicts, or used
1051 `--interactive` to omit, edit, squash, or fixup commits; or
1052 if the upstream used one of `commit --amend`, `reset`, or
1053 a full history rewriting command like
1054 https://github.com/newren/git-filter-repo[`filter-repo`].
1055
1056
1057 The easy case
1058 ~~~~~~~~~~~~~
1059
1060 Only works if the changes (patch IDs based on the diff contents) on
1061 'subsystem' are literally the same before and after the rebase
1062 'subsystem' did.
1063
1064 In that case, the fix is easy because 'git rebase' knows to skip
1065 changes that are already present in the new upstream (unless
1066 `--reapply-cherry-picks` is given). So if you say
1067 (assuming you're on 'topic')
1068 ------------
1069 $ git rebase subsystem
1070 ------------
1071 you will end up with the fixed history
1072 ------------
1073 o---o---o---o---o---o---o---o master
1074 \
1075 o'--o'--o'--o'--o' subsystem
1076 \
1077 *---*---* topic
1078 ------------
1079
1080
1081 The hard case
1082 ~~~~~~~~~~~~~
1083
1084 Things get more complicated if the 'subsystem' changes do not exactly
1085 correspond to the ones before the rebase.
1086
1087 NOTE: While an "easy case recovery" sometimes appears to be successful
1088 even in the hard case, it may have unintended consequences. For
1089 example, a commit that was removed via `git rebase
1090 --interactive` will be **resurrected**!
1091
1092 The idea is to manually tell `git rebase` "where the old 'subsystem'
1093 ended and your 'topic' began", that is, what the old merge base
1094 between them was. You will have to find a way to name the last commit
1095 of the old 'subsystem', for example:
1096
1097 * With the 'subsystem' reflog: after `git fetch`, the old tip of
1098 'subsystem' is at `subsystem@{1}`. Subsequent fetches will
1099 increase the number. (See linkgit:git-reflog[1].)
1100
1101 * Relative to the tip of 'topic': knowing that your 'topic' has three
1102 commits, the old tip of 'subsystem' must be `topic~3`.
1103
1104 You can then transplant the old `subsystem..topic` to the new tip by
1105 saying (for the reflog case, and assuming you are on 'topic' already):
1106 ------------
1107 $ git rebase --onto subsystem subsystem@{1}
1108 ------------
1109
1110 The ripple effect of a "hard case" recovery is especially bad:
1111 'everyone' downstream from 'topic' will now have to perform a "hard
1112 case" recovery too!
1113
1114 REBASING MERGES
1115 ---------------
1116
1117 The interactive rebase command was originally designed to handle
1118 individual patch series. As such, it makes sense to exclude merge
1119 commits from the todo list, as the developer may have merged the
1120 then-current `master` while working on the branch, only to rebase
1121 all the commits onto `master` eventually (skipping the merge
1122 commits).
1123
1124 However, there are legitimate reasons why a developer may want to
1125 recreate merge commits: to keep the branch structure (or "commit
1126 topology") when working on multiple, inter-related branches.
1127
1128 In the following example, the developer works on a topic branch that
1129 refactors the way buttons are defined, and on another topic branch
1130 that uses that refactoring to implement a "Report a bug" button. The
1131 output of `git log --graph --format=%s -5` may look like this:
1132
1133 ------------
1134 * Merge branch 'report-a-bug'
1135 |\
1136 | * Add the feedback button
1137 * | Merge branch 'refactor-button'
1138 |\ \
1139 | |/
1140 | * Use the Button class for all buttons
1141 | * Extract a generic Button class from the DownloadButton one
1142 ------------
1143
1144 The developer might want to rebase those commits to a newer `master`
1145 while keeping the branch topology, for example when the first topic
1146 branch is expected to be integrated into `master` much earlier than the
1147 second one, say, to resolve merge conflicts with changes to the
1148 DownloadButton class that made it into `master`.
1149
1150 This rebase can be performed using the `--rebase-merges` option.
1151 It will generate a todo list looking like this:
1152
1153 ------------
1154 label onto
1155
1156 # Branch: refactor-button
1157 reset onto
1158 pick 123456 Extract a generic Button class from the DownloadButton one
1159 pick 654321 Use the Button class for all buttons
1160 label refactor-button
1161
1162 # Branch: report-a-bug
1163 reset refactor-button # Use the Button class for all buttons
1164 pick abcdef Add the feedback button
1165 label report-a-bug
1166
1167 reset onto
1168 merge -C a1b2c3 refactor-button # Merge 'refactor-button'
1169 merge -C 6f5e4d report-a-bug # Merge 'report-a-bug'
1170 ------------
1171
1172 In contrast to a regular interactive rebase, there are `label`, `reset`
1173 and `merge` commands in addition to `pick` ones.
1174
1175 The `label` command associates a label with the current HEAD when that
1176 command is executed. These labels are created as worktree-local refs
1177 (`refs/rewritten/<label>`) that will be deleted when the rebase
1178 finishes. That way, rebase operations in multiple worktrees linked to
1179 the same repository do not interfere with one another. If the `label`
1180 command fails, it is rescheduled immediately, with a helpful message how
1181 to proceed.
1182
1183 The `reset` command resets the HEAD, index and worktree to the specified
1184 revision. It is similar to an `exec git reset --hard <label>`, but
1185 refuses to overwrite untracked files. If the `reset` command fails, it is
1186 rescheduled immediately, with a helpful message how to edit the todo list
1187 (this typically happens when a `reset` command was inserted into the todo
1188 list manually and contains a typo).
1189
1190 The `merge` command will merge the specified revision(s) into whatever
1191 is HEAD at that time. With `-C <original-commit>`, the commit message of
1192 the specified merge commit will be used. When the `-C` is changed to
1193 a lower-case `-c`, the message will be opened in an editor after a
1194 successful merge so that the user can edit the message.
1195
1196 If a `merge` command fails for any reason other than merge conflicts (i.e.
1197 when the merge operation did not even start), it is rescheduled immediately.
1198
1199 By default, the `merge` command will use the `ort` merge strategy for
1200 regular merges, and `octopus` for octopus merges. One can specify a
1201 default strategy for all merges using the `--strategy` argument when
1202 invoking rebase, or can override specific merges in the interactive
1203 list of commands by using an `exec` command to call `git merge`
1204 explicitly with a `--strategy` argument. Note that when calling `git
1205 merge` explicitly like this, you can make use of the fact that the
1206 labels are worktree-local refs (the ref `refs/rewritten/onto` would
1207 correspond to the label `onto`, for example) in order to refer to the
1208 branches you want to merge.
1209
1210 Note: the first command (`label onto`) labels the revision onto which
1211 the commits are rebased; The name `onto` is just a convention, as a nod
1212 to the `--onto` option.
1213
1214 It is also possible to introduce completely new merge commits from scratch
1215 by adding a command of the form `merge <merge-head>`. This form will
1216 generate a tentative commit message and always open an editor to let the
1217 user edit it. This can be useful e.g. when a topic branch turns out to
1218 address more than a single concern and wants to be split into two or
1219 even more topic branches. Consider this todo list:
1220
1221 ------------
1222 pick 192837 Switch from GNU Makefiles to CMake
1223 pick 5a6c7e Document the switch to CMake
1224 pick 918273 Fix detection of OpenSSL in CMake
1225 pick afbecd http: add support for TLS v1.3
1226 pick fdbaec Fix detection of cURL in CMake on Windows
1227 ------------
1228
1229 The one commit in this list that is not related to CMake may very well
1230 have been motivated by working on fixing all those bugs introduced by
1231 switching to CMake, but it addresses a different concern. To split this
1232 branch into two topic branches, the todo list could be edited like this:
1233
1234 ------------
1235 label onto
1236
1237 pick afbecd http: add support for TLS v1.3
1238 label tlsv1.3
1239
1240 reset onto
1241 pick 192837 Switch from GNU Makefiles to CMake
1242 pick 918273 Fix detection of OpenSSL in CMake
1243 pick fdbaec Fix detection of cURL in CMake on Windows
1244 pick 5a6c7e Document the switch to CMake
1245 label cmake
1246
1247 reset onto
1248 merge tlsv1.3
1249 merge cmake
1250 ------------
1251
1252 CONFIGURATION
1253 -------------
1254
1255 include::config/rebase.txt[]
1256 include::config/sequencer.txt[]
1257
1258 GIT
1259 ---
1260 Part of the linkgit:git[1] suite