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