Merge branch 'dl/subtree-limit-to-one-rev'
[git/git.git] / Documentation / git-rebase.txt
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>] [--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
17 DESCRIPTION
18 -----------
19 If <branch> is specified, 'git rebase' will perform an automatic
20 `git checkout <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 the
52 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. For example, running `git rebase master` on the
83 following history (in which `A'` and `A` introduce the same set of changes,
84 but have different committer information):
85
86 ------------
87 A---B---C topic
88 /
89 D---E---A'---F master
90 ------------
91
92 will result in:
93
94 ------------
95 B'---C' topic
96 /
97 D---E---A'---F master
98 ------------
99
100 Here is how you would transplant a topic branch based on one
101 branch to another, to pretend that you forked the topic branch
102 from the latter branch, using `rebase --onto`.
103
104 First let's assume your 'topic' is based on branch 'next'.
105 For example, a feature developed in 'topic' depends on some
106 functionality 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
116 We want to make 'topic' forked from branch 'master'; for example,
117 because the functionality on which 'topic' depends was merged into the
118 more 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
128 We can get this using the following command:
129
130 git rebase --onto master next topic
131
132
133 Another example of --onto option is to rebase part of a
134 branch. 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
144 then the command
145
146 git rebase --onto master topicA topicB
147
148 would result in:
149
150 ------------
151 H'--I'--J' topicB
152 /
153 | E---F---G topicA
154 |/
155 A---B---C---D master
156 ------------
157
158 This is useful when topicB does not depend on topicA.
159
160 A range of commits could also be removed with rebase. If we have
161 the following situation:
162
163 ------------
164 E---F---G---H---I---J topicA
165 ------------
166
167 then the command
168
169 git rebase --onto topicA~5 topicA~3 topicA
170
171 would result in the removal of commits F and G:
172
173 ------------
174 E---H'---I'---J' topicA
175 ------------
176
177 This is useful if F and G were flawed in some way, or should not be
178 part of topicA. Note that the argument to --onto and the <upstream>
179 parameter can be any valid commit-ish.
180
181 In case of conflict, 'git rebase' will stop at the first problematic commit
182 and leave conflict markers in the tree. You can use 'git diff' to locate
183 the markers (<<<<<<) and make edits to resolve the conflict. For each
184 file you edit, you need to tell Git that the conflict has been resolved,
185 typically this would be done with
186
187
188 git add <filename>
189
190
191 After resolving the conflict manually and updating the index with the
192 desired resolution, you can continue the rebasing process with
193
194
195 git rebase --continue
196
197
198 Alternatively, you can undo the 'git rebase' with
199
200
201 git rebase --abort
202
203 CONFIGURATION
204 -------------
205
206 include::config/rebase.txt[]
207
208 OPTIONS
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 +
216 As a special case, you may use "A\...B" as a shortcut for the
217 merge base of A and B if there is exactly one merge base. You can
218 leave 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 +
247 See 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 +
254 See 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 +
273 Note that a rebase merge works by replaying each commit from the working
274 branch on top of the <upstream> branch. Because of this, when a merge
275 conflict happens, the side reported as 'ours' is the so-far rebased
276 series, starting with <upstream>, and 'theirs' is the working branch. In
277 other words, the sides are swapped.
278 +
279 See 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 +
287 Because 'git rebase' replays each commit from the working branch
288 on top of the <upstream> branch using the given strategy, using
289 the 'ours' strategy simply empties all patches from the <branch>,
290 which makes little sense.
291 +
292 See 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 +
301 See 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 +
338 See 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 +
347 You may find this helpful after reverting a topic branch merge, as this option
348 recreates the topic branch with fresh commits so it can be remerged
349 successfully without needing to "revert the reversion" (see the
350 link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for
351 details).
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 +
359 When --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'
363 ends up being empty, the <upstream> will be used as a fallback.
364 +
365 If either <upstream> or --root is given on the command line, then the
366 default 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 +
373 See 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 +
380 See 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 +
387 See 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 +
395 The commit list format can be changed by setting the configuration option
396 rebase.instructionFormat. A customized instruction format will automatically
397 have the long commit hash prepended to the format.
398 +
399 See 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 +
411 By default, or when `no-rebase-cousins` was specified, commits which do not
412 have `<upstream>` as direct ancestor will keep their original branch point,
413 i.e. commits that would be excluded by linkgit:git-log[1]'s
414 `--ancestry-path` option will keep their original ancestry by default. If
415 the `rebase-cousins` mode is turned on, such commits are instead rebased
416 onto `<upstream>` (or `<onto>`, if specified).
417 +
418 The `--rebase-merges` mode is similar in spirit to the deprecated
419 `--preserve-merges`, but in contrast to that option works well in interactive
420 rebases: commits can be reordered, inserted and dropped at will.
421 +
422 It is currently only possible to recreate the merge commits using the
423 `recursive` merge strategy; Different merge strategies can be used only via
424 explicit `exec git merge -s <strategy> [...]` commands.
425 +
426 See also REBASING MERGES and INCOMPATIBLE OPTIONS below.
427
428 -p::
429 --preserve-merges::
430 [DEPRECATED: use `--rebase-merges` instead] Recreate merge commits
431 instead of flattening the history by replaying commits a merge commit
432 introduces. Merge conflict resolutions or manual amendments to merge
433 commits are not preserved.
434 +
435 This uses the `--interactive` machinery internally, but combining it
436 with the `--interactive` option explicitly is generally not a good
437 idea unless you know what you are doing (see BUGS below).
438 +
439 See also INCOMPATIBLE OPTIONS below.
440
441 -x <cmd>::
442 --exec <cmd>::
443 Append "exec <cmd>" after each line creating a commit in the
444 final history. <cmd> will be interpreted as one or more shell
445 commands. Any command that fails will interrupt the rebase,
446 with exit code 1.
447 +
448 You may execute several commands by either using one instance of `--exec`
449 with several commands:
450 +
451 git rebase -i --exec "cmd1 && cmd2 && ..."
452 +
453 or by giving more than one `--exec`:
454 +
455 git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
456 +
457 If `--autosquash` is used, "exec" lines will not be appended for
458 the intermediate commits, and will only appear at the end of each
459 squash/fixup series.
460 +
461 This uses the `--interactive` machinery internally, but it can be run
462 without an explicit `--interactive`.
463 +
464 See also INCOMPATIBLE OPTIONS below.
465
466 --root::
467 Rebase all commits reachable from <branch>, instead of
468 limiting them with an <upstream>. This allows you to rebase
469 the root commit(s) on a branch. When used with --onto, it
470 will skip changes already contained in <newbase> (instead of
471 <upstream>) whereas without --onto it will operate on every change.
472 When used together with both --onto and --preserve-merges,
473 'all' root commits will be rewritten to have <newbase> as parent
474 instead.
475 +
476 See also INCOMPATIBLE OPTIONS below.
477
478 --autosquash::
479 --no-autosquash::
480 When the commit log message begins with "squash! ..." (or
481 "fixup! ..."), and there is already a commit in the todo list that
482 matches the same `...`, automatically modify the todo list of rebase
483 -i so that the commit marked for squashing comes right after the
484 commit to be modified, and change the action of the moved commit
485 from `pick` to `squash` (or `fixup`). A commit matches the `...` if
486 the commit subject matches, or if the `...` refers to the commit's
487 hash. As a fall-back, partial matches of the commit subject work,
488 too. The recommended way to create fixup/squash commits is by using
489 the `--fixup`/`--squash` options of linkgit:git-commit[1].
490 +
491 If the `--autosquash` option is enabled by default using the
492 configuration variable `rebase.autoSquash`, this option can be
493 used to override and disable this setting.
494 +
495 See also INCOMPATIBLE OPTIONS below.
496
497 --autostash::
498 --no-autostash::
499 Automatically create a temporary stash entry before the operation
500 begins, and apply it after the operation ends. This means
501 that you can run rebase on a dirty worktree. However, use
502 with care: the final stash application after a successful
503 rebase might result in non-trivial conflicts.
504
505 --reschedule-failed-exec::
506 --no-reschedule-failed-exec::
507 Automatically reschedule `exec` commands that failed. This only makes
508 sense in interactive mode (or when an `--exec` option was provided).
509
510 INCOMPATIBLE OPTIONS
511 --------------------
512
513 The following options:
514
515 * --committer-date-is-author-date
516 * --ignore-date
517 * --whitespace
518 * --ignore-whitespace
519 * -C
520
521 are incompatible with the following options:
522
523 * --merge
524 * --strategy
525 * --strategy-option
526 * --allow-empty-message
527 * --[no-]autosquash
528 * --rebase-merges
529 * --preserve-merges
530 * --interactive
531 * --exec
532 * --keep-empty
533 * --edit-todo
534 * --root when used in combination with --onto
535
536 In addition, the following pairs of options are incompatible:
537
538 * --preserve-merges and --interactive
539 * --preserve-merges and --signoff
540 * --preserve-merges and --rebase-merges
541 * --rebase-merges and --strategy
542 * --rebase-merges and --strategy-option
543
544 BEHAVIORAL DIFFERENCES
545 -----------------------
546
547 There are some subtle differences how the backends behave.
548
549 Empty commits
550 ~~~~~~~~~~~~~
551
552 The am backend drops any "empty" commits, regardless of whether the
553 commit started empty (had no changes relative to its parent to
554 start with) or ended empty (all changes were already applied
555 upstream in other commits).
556
557 The interactive backend drops commits by default that
558 started empty and halts if it hits a commit that ended up empty.
559 The `--keep-empty` option exists for the interactive backend to allow
560 it to keep commits that started empty.
561
562 Directory rename detection
563 ~~~~~~~~~~~~~~~~~~~~~~~~~~
564
565 Directory rename heuristics are enabled in the merge and interactive
566 backends. Due to the lack of accurate tree information, directory
567 rename detection is disabled in the am backend.
568
569 include::merge-strategies.txt[]
570
571 NOTES
572 -----
573
574 You should understand the implications of using 'git rebase' on a
575 repository that you share. See also RECOVERING FROM UPSTREAM REBASE
576 below.
577
578 When the git-rebase command is run, it will first execute a "pre-rebase"
579 hook if one exists. You can use this hook to do sanity checks and
580 reject the rebase if it isn't appropriate. Please see the template
581 pre-rebase hook script for an example.
582
583 Upon completion, <branch> will be the current branch.
584
585 INTERACTIVE MODE
586 ----------------
587
588 Rebasing interactively means that you have a chance to edit the commits
589 which are rebased. You can reorder the commits, and you can
590 remove them (weeding out bad or otherwise unwanted patches).
591
592 The interactive mode is meant for this type of workflow:
593
594 1. have a wonderful idea
595 2. hack on the code
596 3. prepare a series for submission
597 4. submit
598
599 where point 2. consists of several instances of
600
601 a) regular use
602
603 1. finish something worthy of a commit
604 2. commit
605
606 b) independent fixup
607
608 1. realize that something does not work
609 2. fix that
610 3. commit it
611
612 Sometimes the thing fixed in b.2. cannot be amended to the not-quite
613 perfect commit it fixes, because that commit is buried deeply in a
614 patch series. That is exactly what interactive rebase is for: use it
615 after plenty of "a"s and "b"s, by rearranging and editing
616 commits, and squashing multiple commits into one.
617
618 Start it with the last commit you want to retain as-is:
619
620 git rebase -i <after-this-commit>
621
622 An editor will be fired up with all the commits in your current branch
623 (ignoring merge commits), which come after the given commit. You can
624 reorder the commits in this list to your heart's content, and you can
625 remove them. The list looks more or less like this:
626
627 -------------------------------------------
628 pick deadbee The oneline of this commit
629 pick fa1afe1 The oneline of the next commit
630 ...
631 -------------------------------------------
632
633 The oneline descriptions are purely for your pleasure; 'git rebase' will
634 not look at them but at the commit names ("deadbee" and "fa1afe1" in this
635 example), so do not delete or edit the names.
636
637 By replacing the command "pick" with the command "edit", you can tell
638 'git rebase' to stop after applying that commit, so that you can edit
639 the files and/or the commit message, amend the commit, and continue
640 rebasing.
641
642 To interrupt the rebase (just like an "edit" command would do, but without
643 cherry-picking any commit first), use the "break" command.
644
645 If you just want to edit the commit message for a commit, replace the
646 command "pick" with the command "reword".
647
648 To drop a commit, replace the command "pick" with "drop", or just
649 delete the matching line.
650
651 If you want to fold two or more commits into one, replace the command
652 "pick" for the second and subsequent commits with "squash" or "fixup".
653 If the commits had different authors, the folded commit will be
654 attributed to the author of the first commit. The suggested commit
655 message for the folded commit is the concatenation of the commit
656 messages of the first commit and of those with the "squash" command,
657 but omits the commit messages of commits with the "fixup" command.
658
659 'git rebase' will stop when "pick" has been replaced with "edit" or
660 when a command fails due to merge errors. When you are done editing
661 and/or resolving conflicts you can continue with `git rebase --continue`.
662
663 For example, if you want to reorder the last 5 commits, such that what
664 was HEAD~4 becomes the new HEAD. To achieve that, you would call
665 'git rebase' like this:
666
667 ----------------------
668 $ git rebase -i HEAD~5
669 ----------------------
670
671 And move the first patch to the end of the list.
672
673 You might want to preserve merges, if you have a history like this:
674
675 ------------------
676 X
677 \
678 A---M---B
679 /
680 ---o---O---P---Q
681 ------------------
682
683 Suppose you want to rebase the side branch starting at "A" to "Q". Make
684 sure that the current HEAD is "B", and call
685
686 -----------------------------
687 $ git rebase -i -p --onto Q O
688 -----------------------------
689
690 Reordering and editing commits usually creates untested intermediate
691 steps. You may want to check that your history editing did not break
692 anything by running a test, or at least recompiling at intermediate
693 points in history by using the "exec" command (shortcut "x"). You may
694 do so by creating a todo list like this one:
695
696 -------------------------------------------
697 pick deadbee Implement feature XXX
698 fixup f1a5c00 Fix to feature XXX
699 exec make
700 pick c0ffeee The oneline of the next commit
701 edit deadbab The oneline of the commit after
702 exec cd subdir; make test
703 ...
704 -------------------------------------------
705
706 The interactive rebase will stop when a command fails (i.e. exits with
707 non-0 status) to give you an opportunity to fix the problem. You can
708 continue with `git rebase --continue`.
709
710 The "exec" command launches the command in a shell (the one specified
711 in `$SHELL`, or the default shell if `$SHELL` is not set), so you can
712 use shell features (like "cd", ">", ";" ...). The command is run from
713 the root of the working tree.
714
715 ----------------------------------
716 $ git rebase -i --exec "make test"
717 ----------------------------------
718
719 This command lets you check that intermediate commits are compilable.
720 The todo list becomes like that:
721
722 --------------------
723 pick 5928aea one
724 exec make test
725 pick 04d0fda two
726 exec make test
727 pick ba46169 three
728 exec make test
729 pick f4593f9 four
730 exec make test
731 --------------------
732
733 SPLITTING COMMITS
734 -----------------
735
736 In interactive mode, you can mark commits with the action "edit". However,
737 this does not necessarily mean that 'git rebase' expects the result of this
738 edit to be exactly one commit. Indeed, you can undo the commit, or you can
739 add other commits. This can be used to split a commit into two:
740
741 - Start an interactive rebase with `git rebase -i <commit>^`, where
742 <commit> is the commit you want to split. In fact, any commit range
743 will do, as long as it contains that commit.
744
745 - Mark the commit you want to split with the action "edit".
746
747 - When it comes to editing that commit, execute `git reset HEAD^`. The
748 effect is that the HEAD is rewound by one, and the index follows suit.
749 However, the working tree stays the same.
750
751 - Now add the changes to the index that you want to have in the first
752 commit. You can use `git add` (possibly interactively) or
753 'git gui' (or both) to do that.
754
755 - Commit the now-current index with whatever commit message is appropriate
756 now.
757
758 - Repeat the last two steps until your working tree is clean.
759
760 - Continue the rebase with `git rebase --continue`.
761
762 If you are not absolutely sure that the intermediate revisions are
763 consistent (they compile, pass the testsuite, etc.) you should use
764 'git stash' to stash away the not-yet-committed changes
765 after each commit, test, and amend the commit if fixes are necessary.
766
767
768 RECOVERING FROM UPSTREAM REBASE
769 -------------------------------
770
771 Rebasing (or any other form of rewriting) a branch that others have
772 based work on is a bad idea: anyone downstream of it is forced to
773 manually fix their history. This section explains how to do the fix
774 from the downstream's point of view. The real fix, however, would be
775 to avoid rebasing the upstream in the first place.
776
777 To illustrate, suppose you are in a situation where someone develops a
778 'subsystem' branch, and you are working on a 'topic' that is dependent
779 on this 'subsystem'. You might end up with a history like the
780 following:
781
782 ------------
783 o---o---o---o---o---o---o---o master
784 \
785 o---o---o---o---o subsystem
786 \
787 *---*---* topic
788 ------------
789
790 If 'subsystem' is rebased against 'master', the following happens:
791
792 ------------
793 o---o---o---o---o---o---o---o master
794 \ \
795 o---o---o---o---o o'--o'--o'--o'--o' subsystem
796 \
797 *---*---* topic
798 ------------
799
800 If you now continue development as usual, and eventually merge 'topic'
801 to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
802
803 ------------
804 o---o---o---o---o---o---o---o master
805 \ \
806 o---o---o---o---o o'--o'--o'--o'--o'--M subsystem
807 \ /
808 *---*---*-..........-*--* topic
809 ------------
810
811 Such duplicates are generally frowned upon because they clutter up
812 history, making it harder to follow. To clean things up, you need to
813 transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
814 rebase 'topic'. This becomes a ripple effect: anyone downstream from
815 'topic' is forced to rebase too, and so on!
816
817 There are two kinds of fixes, discussed in the following subsections:
818
819 Easy case: The changes are literally the same.::
820
821 This happens if the 'subsystem' rebase was a simple rebase and
822 had no conflicts.
823
824 Hard case: The changes are not the same.::
825
826 This happens if the 'subsystem' rebase had conflicts, or used
827 `--interactive` to omit, edit, squash, or fixup commits; or
828 if the upstream used one of `commit --amend`, `reset`, or
829 `filter-branch`.
830
831
832 The easy case
833 ~~~~~~~~~~~~~
834
835 Only works if the changes (patch IDs based on the diff contents) on
836 'subsystem' are literally the same before and after the rebase
837 'subsystem' did.
838
839 In that case, the fix is easy because 'git rebase' knows to skip
840 changes that are already present in the new upstream. So if you say
841 (assuming you're on 'topic')
842 ------------
843 $ git rebase subsystem
844 ------------
845 you will end up with the fixed history
846 ------------
847 o---o---o---o---o---o---o---o master
848 \
849 o'--o'--o'--o'--o' subsystem
850 \
851 *---*---* topic
852 ------------
853
854
855 The hard case
856 ~~~~~~~~~~~~~
857
858 Things get more complicated if the 'subsystem' changes do not exactly
859 correspond to the ones before the rebase.
860
861 NOTE: While an "easy case recovery" sometimes appears to be successful
862 even in the hard case, it may have unintended consequences. For
863 example, a commit that was removed via `git rebase
864 --interactive` will be **resurrected**!
865
866 The idea is to manually tell 'git rebase' "where the old 'subsystem'
867 ended and your 'topic' began", that is, what the old merge-base
868 between them was. You will have to find a way to name the last commit
869 of the old 'subsystem', for example:
870
871 * With the 'subsystem' reflog: after 'git fetch', the old tip of
872 'subsystem' is at `subsystem@{1}`. Subsequent fetches will
873 increase the number. (See linkgit:git-reflog[1].)
874
875 * Relative to the tip of 'topic': knowing that your 'topic' has three
876 commits, the old tip of 'subsystem' must be `topic~3`.
877
878 You can then transplant the old `subsystem..topic` to the new tip by
879 saying (for the reflog case, and assuming you are on 'topic' already):
880 ------------
881 $ git rebase --onto subsystem subsystem@{1}
882 ------------
883
884 The ripple effect of a "hard case" recovery is especially bad:
885 'everyone' downstream from 'topic' will now have to perform a "hard
886 case" recovery too!
887
888 REBASING MERGES
889 ---------------
890
891 The interactive rebase command was originally designed to handle
892 individual patch series. As such, it makes sense to exclude merge
893 commits from the todo list, as the developer may have merged the
894 then-current `master` while working on the branch, only to rebase
895 all the commits onto `master` eventually (skipping the merge
896 commits).
897
898 However, there are legitimate reasons why a developer may want to
899 recreate merge commits: to keep the branch structure (or "commit
900 topology") when working on multiple, inter-related branches.
901
902 In the following example, the developer works on a topic branch that
903 refactors the way buttons are defined, and on another topic branch
904 that uses that refactoring to implement a "Report a bug" button. The
905 output of `git log --graph --format=%s -5` may look like this:
906
907 ------------
908 * Merge branch 'report-a-bug'
909 |\
910 | * Add the feedback button
911 * | Merge branch 'refactor-button'
912 |\ \
913 | |/
914 | * Use the Button class for all buttons
915 | * Extract a generic Button class from the DownloadButton one
916 ------------
917
918 The developer might want to rebase those commits to a newer `master`
919 while keeping the branch topology, for example when the first topic
920 branch is expected to be integrated into `master` much earlier than the
921 second one, say, to resolve merge conflicts with changes to the
922 DownloadButton class that made it into `master`.
923
924 This rebase can be performed using the `--rebase-merges` option.
925 It will generate a todo list looking like this:
926
927 ------------
928 label onto
929
930 # Branch: refactor-button
931 reset onto
932 pick 123456 Extract a generic Button class from the DownloadButton one
933 pick 654321 Use the Button class for all buttons
934 label refactor-button
935
936 # Branch: report-a-bug
937 reset refactor-button # Use the Button class for all buttons
938 pick abcdef Add the feedback button
939 label report-a-bug
940
941 reset onto
942 merge -C a1b2c3 refactor-button # Merge 'refactor-button'
943 merge -C 6f5e4d report-a-bug # Merge 'report-a-bug'
944 ------------
945
946 In contrast to a regular interactive rebase, there are `label`, `reset`
947 and `merge` commands in addition to `pick` ones.
948
949 The `label` command associates a label with the current HEAD when that
950 command is executed. These labels are created as worktree-local refs
951 (`refs/rewritten/<label>`) that will be deleted when the rebase
952 finishes. That way, rebase operations in multiple worktrees linked to
953 the same repository do not interfere with one another. If the `label`
954 command fails, it is rescheduled immediately, with a helpful message how
955 to proceed.
956
957 The `reset` command resets the HEAD, index and worktree to the specified
958 revision. It is similar to an `exec git reset --hard <label>`, but
959 refuses to overwrite untracked files. If the `reset` command fails, it is
960 rescheduled immediately, with a helpful message how to edit the todo list
961 (this typically happens when a `reset` command was inserted into the todo
962 list manually and contains a typo).
963
964 The `merge` command will merge the specified revision(s) into whatever
965 is HEAD at that time. With `-C <original-commit>`, the commit message of
966 the specified merge commit will be used. When the `-C` is changed to
967 a lower-case `-c`, the message will be opened in an editor after a
968 successful merge so that the user can edit the message.
969
970 If a `merge` command fails for any reason other than merge conflicts (i.e.
971 when the merge operation did not even start), it is rescheduled immediately.
972
973 At this time, the `merge` command will *always* use the `recursive`
974 merge strategy for regular merges, and `octopus` for octopus merges,
975 with no way to choose a different one. To work around
976 this, an `exec` command can be used to call `git merge` explicitly,
977 using the fact that the labels are worktree-local refs (the ref
978 `refs/rewritten/onto` would correspond to the label `onto`, for example).
979
980 Note: the first command (`label onto`) labels the revision onto which
981 the commits are rebased; The name `onto` is just a convention, as a nod
982 to the `--onto` option.
983
984 It is also possible to introduce completely new merge commits from scratch
985 by adding a command of the form `merge <merge-head>`. This form will
986 generate a tentative commit message and always open an editor to let the
987 user edit it. This can be useful e.g. when a topic branch turns out to
988 address more than a single concern and wants to be split into two or
989 even more topic branches. Consider this todo list:
990
991 ------------
992 pick 192837 Switch from GNU Makefiles to CMake
993 pick 5a6c7e Document the switch to CMake
994 pick 918273 Fix detection of OpenSSL in CMake
995 pick afbecd http: add support for TLS v1.3
996 pick fdbaec Fix detection of cURL in CMake on Windows
997 ------------
998
999 The one commit in this list that is not related to CMake may very well
1000 have been motivated by working on fixing all those bugs introduced by
1001 switching to CMake, but it addresses a different concern. To split this
1002 branch into two topic branches, the todo list could be edited like this:
1003
1004 ------------
1005 label onto
1006
1007 pick afbecd http: add support for TLS v1.3
1008 label tlsv1.3
1009
1010 reset onto
1011 pick 192837 Switch from GNU Makefiles to CMake
1012 pick 918273 Fix detection of OpenSSL in CMake
1013 pick fdbaec Fix detection of cURL in CMake on Windows
1014 pick 5a6c7e Document the switch to CMake
1015 label cmake
1016
1017 reset onto
1018 merge tlsv1.3
1019 merge cmake
1020 ------------
1021
1022 BUGS
1023 ----
1024 The todo list presented by the deprecated `--preserve-merges --interactive`
1025 does not represent the topology of the revision graph (use `--rebase-merges`
1026 instead). Editing commits and rewording their commit messages should work
1027 fine, but attempts to reorder commits tend to produce counterintuitive results.
1028 Use `--rebase-merges` in such scenarios instead.
1029
1030 For example, an attempt to rearrange
1031 ------------
1032 1 --- 2 --- 3 --- 4 --- 5
1033 ------------
1034 to
1035 ------------
1036 1 --- 2 --- 4 --- 3 --- 5
1037 ------------
1038 by moving the "pick 4" line will result in the following history:
1039 ------------
1040 3
1041 /
1042 1 --- 2 --- 4 --- 5
1043 ------------
1044
1045 GIT
1046 ---
1047 Part of the linkgit:git[1] suite