Merge branch 'dl/rebase-i-keep-base'
[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>]
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 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 --keep-base::
221 Set the starting point at which to create the new commits to the
222 merge base of <upstream> <branch>. Running
223 'git rebase --keep-base <upstream> <branch>' is equivalent to
224 running 'git rebase --onto <upstream>... <upstream>'.
225 +
226 This option is useful in the case where one is developing a feature on
227 top of an upstream branch. While the feature is being worked on, the
228 upstream branch may advance and it may not be the best idea to keep
229 rebasing on top of the upstream but to keep the base commit as-is.
230 +
231 Although both this option and --fork-point find the merge base between
232 <upstream> and <branch>, this option uses the merge base as the _starting
233 point_ on which new commits will be created, whereas --fork-point uses
234 the merge base to determine the _set of commits_ which will be rebased.
235 +
236 See also INCOMPATIBLE OPTIONS below.
237
238 <upstream>::
239 Upstream branch to compare against. May be any valid commit,
240 not just an existing branch name. Defaults to the configured
241 upstream for the current branch.
242
243 <branch>::
244 Working branch; defaults to HEAD.
245
246 --continue::
247 Restart the rebasing process after having resolved a merge conflict.
248
249 --abort::
250 Abort the rebase operation and reset HEAD to the original
251 branch. If <branch> was provided when the rebase operation was
252 started, then HEAD will be reset to <branch>. Otherwise HEAD
253 will be reset to where it was when the rebase operation was
254 started.
255
256 --quit::
257 Abort the rebase operation but HEAD is not reset back to the
258 original branch. The index and working tree are also left
259 unchanged as a result.
260
261 --keep-empty::
262 Keep the commits that do not change anything from its
263 parents in the result.
264 +
265 See also INCOMPATIBLE OPTIONS below.
266
267 --allow-empty-message::
268 By default, rebasing commits with an empty message will fail.
269 This option overrides that behavior, allowing commits with empty
270 messages to be rebased.
271 +
272 See also INCOMPATIBLE OPTIONS below.
273
274 --skip::
275 Restart the rebasing process by skipping the current patch.
276
277 --edit-todo::
278 Edit the todo list during an interactive rebase.
279
280 --show-current-patch::
281 Show the current patch in an interactive rebase or when rebase
282 is stopped because of conflicts. This is the equivalent of
283 `git show REBASE_HEAD`.
284
285 -m::
286 --merge::
287 Use merging strategies to rebase. When the recursive (default) merge
288 strategy is used, this allows rebase to be aware of renames on the
289 upstream side.
290 +
291 Note that a rebase merge works by replaying each commit from the working
292 branch on top of the <upstream> branch. Because of this, when a merge
293 conflict happens, the side reported as 'ours' is the so-far rebased
294 series, starting with <upstream>, and 'theirs' is the working branch. In
295 other words, the sides are swapped.
296 +
297 See also INCOMPATIBLE OPTIONS below.
298
299 -s <strategy>::
300 --strategy=<strategy>::
301 Use the given merge strategy.
302 If there is no `-s` option 'git merge-recursive' is used
303 instead. This implies --merge.
304 +
305 Because 'git rebase' replays each commit from the working branch
306 on top of the <upstream> branch using the given strategy, using
307 the 'ours' strategy simply empties all patches from the <branch>,
308 which makes little sense.
309 +
310 See also INCOMPATIBLE OPTIONS below.
311
312 -X <strategy-option>::
313 --strategy-option=<strategy-option>::
314 Pass the <strategy-option> through to the merge strategy.
315 This implies `--merge` and, if no strategy has been
316 specified, `-s recursive`. Note the reversal of 'ours' and
317 'theirs' as noted above for the `-m` option.
318 +
319 See also INCOMPATIBLE OPTIONS below.
320
321 --rerere-autoupdate::
322 --no-rerere-autoupdate::
323 Allow the rerere mechanism to update the index with the
324 result of auto-conflict resolution if possible.
325
326 -S[<keyid>]::
327 --gpg-sign[=<keyid>]::
328 GPG-sign commits. The `keyid` argument is optional and
329 defaults to the committer identity; if specified, it must be
330 stuck to the option without a space.
331
332 -q::
333 --quiet::
334 Be quiet. Implies --no-stat.
335
336 -v::
337 --verbose::
338 Be verbose. Implies --stat.
339
340 --stat::
341 Show a diffstat of what changed upstream since the last rebase. The
342 diffstat is also controlled by the configuration option rebase.stat.
343
344 -n::
345 --no-stat::
346 Do not show a diffstat as part of the rebase process.
347
348 --no-verify::
349 This option bypasses the pre-rebase hook. See also linkgit:githooks[5].
350
351 --verify::
352 Allows the pre-rebase hook to run, which is the default. This option can
353 be used to override --no-verify. See also linkgit:githooks[5].
354
355 -C<n>::
356 Ensure at least <n> lines of surrounding context match before
357 and after each change. When fewer lines of surrounding
358 context exist they all must match. By default no context is
359 ever ignored.
360 +
361 See also INCOMPATIBLE OPTIONS below.
362
363 --no-ff::
364 --force-rebase::
365 -f::
366 Individually replay all rebased commits instead of fast-forwarding
367 over the unchanged ones. This ensures that the entire history of
368 the rebased branch is composed of new commits.
369 +
370 You may find this helpful after reverting a topic branch merge, as this option
371 recreates the topic branch with fresh commits so it can be remerged
372 successfully without needing to "revert the reversion" (see the
373 link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for
374 details).
375
376 --fork-point::
377 --no-fork-point::
378 Use reflog to find a better common ancestor between <upstream>
379 and <branch> when calculating which commits have been
380 introduced by <branch>.
381 +
382 When --fork-point is active, 'fork_point' will be used instead of
383 <upstream> to calculate the set of commits to rebase, where
384 'fork_point' is the result of `git merge-base --fork-point <upstream>
385 <branch>` command (see linkgit:git-merge-base[1]). If 'fork_point'
386 ends up being empty, the <upstream> will be used as a fallback.
387 +
388 If either <upstream> or --root is given on the command line, then the
389 default is `--no-fork-point`, otherwise the default is `--fork-point`.
390 +
391 If your branch was based on <upstream> but <upstream> was rewound and
392 your branch contains commits which were dropped, this option can be used
393 with `--keep-base` in order to drop those commits from your branch.
394
395 --ignore-whitespace::
396 --whitespace=<option>::
397 These flag are passed to the 'git apply' program
398 (see linkgit:git-apply[1]) that applies the patch.
399 +
400 See also INCOMPATIBLE OPTIONS below.
401
402 --committer-date-is-author-date::
403 --ignore-date::
404 These flags are passed to 'git am' to easily change the dates
405 of the rebased commits (see linkgit:git-am[1]).
406 +
407 See also INCOMPATIBLE OPTIONS below.
408
409 --signoff::
410 Add a Signed-off-by: trailer to all the rebased commits. Note
411 that if `--interactive` is given then only commits marked to be
412 picked, edited or reworded will have the trailer added.
413 +
414 See also INCOMPATIBLE OPTIONS below.
415
416 -i::
417 --interactive::
418 Make a list of the commits which are about to be rebased. Let the
419 user edit that list before rebasing. This mode can also be used to
420 split commits (see SPLITTING COMMITS below).
421 +
422 The commit list format can be changed by setting the configuration option
423 rebase.instructionFormat. A customized instruction format will automatically
424 have the long commit hash prepended to the format.
425 +
426 See also INCOMPATIBLE OPTIONS below.
427
428 -r::
429 --rebase-merges[=(rebase-cousins|no-rebase-cousins)]::
430 By default, a rebase will simply drop merge commits from the todo
431 list, and put the rebased commits into a single, linear branch.
432 With `--rebase-merges`, the rebase will instead try to preserve
433 the branching structure within the commits that are to be rebased,
434 by recreating the merge commits. Any resolved merge conflicts or
435 manual amendments in these merge commits will have to be
436 resolved/re-applied manually.
437 +
438 By default, or when `no-rebase-cousins` was specified, commits which do not
439 have `<upstream>` as direct ancestor will keep their original branch point,
440 i.e. commits that would be excluded by linkgit:git-log[1]'s
441 `--ancestry-path` option will keep their original ancestry by default. If
442 the `rebase-cousins` mode is turned on, such commits are instead rebased
443 onto `<upstream>` (or `<onto>`, if specified).
444 +
445 The `--rebase-merges` mode is similar in spirit to the deprecated
446 `--preserve-merges`, but in contrast to that option works well in interactive
447 rebases: commits can be reordered, inserted and dropped at will.
448 +
449 It is currently only possible to recreate the merge commits using the
450 `recursive` merge strategy; Different merge strategies can be used only via
451 explicit `exec git merge -s <strategy> [...]` commands.
452 +
453 See also REBASING MERGES and INCOMPATIBLE OPTIONS below.
454
455 -p::
456 --preserve-merges::
457 [DEPRECATED: use `--rebase-merges` instead] Recreate merge commits
458 instead of flattening the history by replaying commits a merge commit
459 introduces. Merge conflict resolutions or manual amendments to merge
460 commits are not preserved.
461 +
462 This uses the `--interactive` machinery internally, but combining it
463 with the `--interactive` option explicitly is generally not a good
464 idea unless you know what you are doing (see BUGS below).
465 +
466 See also INCOMPATIBLE OPTIONS below.
467
468 -x <cmd>::
469 --exec <cmd>::
470 Append "exec <cmd>" after each line creating a commit in the
471 final history. <cmd> will be interpreted as one or more shell
472 commands. Any command that fails will interrupt the rebase,
473 with exit code 1.
474 +
475 You may execute several commands by either using one instance of `--exec`
476 with several commands:
477 +
478 git rebase -i --exec "cmd1 && cmd2 && ..."
479 +
480 or by giving more than one `--exec`:
481 +
482 git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
483 +
484 If `--autosquash` is used, "exec" lines will not be appended for
485 the intermediate commits, and will only appear at the end of each
486 squash/fixup series.
487 +
488 This uses the `--interactive` machinery internally, but it can be run
489 without an explicit `--interactive`.
490 +
491 See also INCOMPATIBLE OPTIONS below.
492
493 --root::
494 Rebase all commits reachable from <branch>, instead of
495 limiting them with an <upstream>. This allows you to rebase
496 the root commit(s) on a branch. When used with --onto, it
497 will skip changes already contained in <newbase> (instead of
498 <upstream>) whereas without --onto it will operate on every change.
499 When used together with both --onto and --preserve-merges,
500 'all' root commits will be rewritten to have <newbase> as parent
501 instead.
502 +
503 See also INCOMPATIBLE OPTIONS below.
504
505 --autosquash::
506 --no-autosquash::
507 When the commit log message begins with "squash! ..." (or
508 "fixup! ..."), and there is already a commit in the todo list that
509 matches the same `...`, automatically modify the todo list of rebase
510 -i so that the commit marked for squashing comes right after the
511 commit to be modified, and change the action of the moved commit
512 from `pick` to `squash` (or `fixup`). A commit matches the `...` if
513 the commit subject matches, or if the `...` refers to the commit's
514 hash. As a fall-back, partial matches of the commit subject work,
515 too. The recommended way to create fixup/squash commits is by using
516 the `--fixup`/`--squash` options of linkgit:git-commit[1].
517 +
518 If the `--autosquash` option is enabled by default using the
519 configuration variable `rebase.autoSquash`, this option can be
520 used to override and disable this setting.
521 +
522 See also INCOMPATIBLE OPTIONS below.
523
524 --autostash::
525 --no-autostash::
526 Automatically create a temporary stash entry before the operation
527 begins, and apply it after the operation ends. This means
528 that you can run rebase on a dirty worktree. However, use
529 with care: the final stash application after a successful
530 rebase might result in non-trivial conflicts.
531
532 --reschedule-failed-exec::
533 --no-reschedule-failed-exec::
534 Automatically reschedule `exec` commands that failed. This only makes
535 sense in interactive mode (or when an `--exec` option was provided).
536
537 INCOMPATIBLE OPTIONS
538 --------------------
539
540 The following options:
541
542 * --committer-date-is-author-date
543 * --ignore-date
544 * --whitespace
545 * --ignore-whitespace
546 * -C
547
548 are incompatible with the following options:
549
550 * --merge
551 * --strategy
552 * --strategy-option
553 * --allow-empty-message
554 * --[no-]autosquash
555 * --rebase-merges
556 * --preserve-merges
557 * --interactive
558 * --exec
559 * --keep-empty
560 * --edit-todo
561 * --root when used in combination with --onto
562
563 In addition, the following pairs of options are incompatible:
564
565 * --preserve-merges and --interactive
566 * --preserve-merges and --signoff
567 * --preserve-merges and --rebase-merges
568 * --keep-base and --onto
569 * --keep-base and --root
570
571 BEHAVIORAL DIFFERENCES
572 -----------------------
573
574 There are some subtle differences how the backends behave.
575
576 Empty commits
577 ~~~~~~~~~~~~~
578
579 The am backend drops any "empty" commits, regardless of whether the
580 commit started empty (had no changes relative to its parent to
581 start with) or ended empty (all changes were already applied
582 upstream in other commits).
583
584 The interactive backend drops commits by default that
585 started empty and halts if it hits a commit that ended up empty.
586 The `--keep-empty` option exists for the interactive backend to allow
587 it to keep commits that started empty.
588
589 Directory rename detection
590 ~~~~~~~~~~~~~~~~~~~~~~~~~~
591
592 Directory rename heuristics are enabled in the merge and interactive
593 backends. Due to the lack of accurate tree information, directory
594 rename detection is disabled in the am backend.
595
596 include::merge-strategies.txt[]
597
598 NOTES
599 -----
600
601 You should understand the implications of using 'git rebase' on a
602 repository that you share. See also RECOVERING FROM UPSTREAM REBASE
603 below.
604
605 When the git-rebase command is run, it will first execute a "pre-rebase"
606 hook if one exists. You can use this hook to do sanity checks and
607 reject the rebase if it isn't appropriate. Please see the template
608 pre-rebase hook script for an example.
609
610 Upon completion, <branch> will be the current branch.
611
612 INTERACTIVE MODE
613 ----------------
614
615 Rebasing interactively means that you have a chance to edit the commits
616 which are rebased. You can reorder the commits, and you can
617 remove them (weeding out bad or otherwise unwanted patches).
618
619 The interactive mode is meant for this type of workflow:
620
621 1. have a wonderful idea
622 2. hack on the code
623 3. prepare a series for submission
624 4. submit
625
626 where point 2. consists of several instances of
627
628 a) regular use
629
630 1. finish something worthy of a commit
631 2. commit
632
633 b) independent fixup
634
635 1. realize that something does not work
636 2. fix that
637 3. commit it
638
639 Sometimes the thing fixed in b.2. cannot be amended to the not-quite
640 perfect commit it fixes, because that commit is buried deeply in a
641 patch series. That is exactly what interactive rebase is for: use it
642 after plenty of "a"s and "b"s, by rearranging and editing
643 commits, and squashing multiple commits into one.
644
645 Start it with the last commit you want to retain as-is:
646
647 git rebase -i <after-this-commit>
648
649 An editor will be fired up with all the commits in your current branch
650 (ignoring merge commits), which come after the given commit. You can
651 reorder the commits in this list to your heart's content, and you can
652 remove them. The list looks more or less like this:
653
654 -------------------------------------------
655 pick deadbee The oneline of this commit
656 pick fa1afe1 The oneline of the next commit
657 ...
658 -------------------------------------------
659
660 The oneline descriptions are purely for your pleasure; 'git rebase' will
661 not look at them but at the commit names ("deadbee" and "fa1afe1" in this
662 example), so do not delete or edit the names.
663
664 By replacing the command "pick" with the command "edit", you can tell
665 'git rebase' to stop after applying that commit, so that you can edit
666 the files and/or the commit message, amend the commit, and continue
667 rebasing.
668
669 To interrupt the rebase (just like an "edit" command would do, but without
670 cherry-picking any commit first), use the "break" command.
671
672 If you just want to edit the commit message for a commit, replace the
673 command "pick" with the command "reword".
674
675 To drop a commit, replace the command "pick" with "drop", or just
676 delete the matching line.
677
678 If you want to fold two or more commits into one, replace the command
679 "pick" for the second and subsequent commits with "squash" or "fixup".
680 If the commits had different authors, the folded commit will be
681 attributed to the author of the first commit. The suggested commit
682 message for the folded commit is the concatenation of the commit
683 messages of the first commit and of those with the "squash" command,
684 but omits the commit messages of commits with the "fixup" command.
685
686 'git rebase' will stop when "pick" has been replaced with "edit" or
687 when a command fails due to merge errors. When you are done editing
688 and/or resolving conflicts you can continue with `git rebase --continue`.
689
690 For example, if you want to reorder the last 5 commits, such that what
691 was HEAD~4 becomes the new HEAD. To achieve that, you would call
692 'git rebase' like this:
693
694 ----------------------
695 $ git rebase -i HEAD~5
696 ----------------------
697
698 And move the first patch to the end of the list.
699
700 You might want to recreate merge commits, e.g. if you have a history
701 like this:
702
703 ------------------
704 X
705 \
706 A---M---B
707 /
708 ---o---O---P---Q
709 ------------------
710
711 Suppose you want to rebase the side branch starting at "A" to "Q". Make
712 sure that the current HEAD is "B", and call
713
714 -----------------------------
715 $ git rebase -i -r --onto Q O
716 -----------------------------
717
718 Reordering and editing commits usually creates untested intermediate
719 steps. You may want to check that your history editing did not break
720 anything by running a test, or at least recompiling at intermediate
721 points in history by using the "exec" command (shortcut "x"). You may
722 do so by creating a todo list like this one:
723
724 -------------------------------------------
725 pick deadbee Implement feature XXX
726 fixup f1a5c00 Fix to feature XXX
727 exec make
728 pick c0ffeee The oneline of the next commit
729 edit deadbab The oneline of the commit after
730 exec cd subdir; make test
731 ...
732 -------------------------------------------
733
734 The interactive rebase will stop when a command fails (i.e. exits with
735 non-0 status) to give you an opportunity to fix the problem. You can
736 continue with `git rebase --continue`.
737
738 The "exec" command launches the command in a shell (the one specified
739 in `$SHELL`, or the default shell if `$SHELL` is not set), so you can
740 use shell features (like "cd", ">", ";" ...). The command is run from
741 the root of the working tree.
742
743 ----------------------------------
744 $ git rebase -i --exec "make test"
745 ----------------------------------
746
747 This command lets you check that intermediate commits are compilable.
748 The todo list becomes like that:
749
750 --------------------
751 pick 5928aea one
752 exec make test
753 pick 04d0fda two
754 exec make test
755 pick ba46169 three
756 exec make test
757 pick f4593f9 four
758 exec make test
759 --------------------
760
761 SPLITTING COMMITS
762 -----------------
763
764 In interactive mode, you can mark commits with the action "edit". However,
765 this does not necessarily mean that 'git rebase' expects the result of this
766 edit to be exactly one commit. Indeed, you can undo the commit, or you can
767 add other commits. This can be used to split a commit into two:
768
769 - Start an interactive rebase with `git rebase -i <commit>^`, where
770 <commit> is the commit you want to split. In fact, any commit range
771 will do, as long as it contains that commit.
772
773 - Mark the commit you want to split with the action "edit".
774
775 - When it comes to editing that commit, execute `git reset HEAD^`. The
776 effect is that the HEAD is rewound by one, and the index follows suit.
777 However, the working tree stays the same.
778
779 - Now add the changes to the index that you want to have in the first
780 commit. You can use `git add` (possibly interactively) or
781 'git gui' (or both) to do that.
782
783 - Commit the now-current index with whatever commit message is appropriate
784 now.
785
786 - Repeat the last two steps until your working tree is clean.
787
788 - Continue the rebase with `git rebase --continue`.
789
790 If you are not absolutely sure that the intermediate revisions are
791 consistent (they compile, pass the testsuite, etc.) you should use
792 'git stash' to stash away the not-yet-committed changes
793 after each commit, test, and amend the commit if fixes are necessary.
794
795
796 RECOVERING FROM UPSTREAM REBASE
797 -------------------------------
798
799 Rebasing (or any other form of rewriting) a branch that others have
800 based work on is a bad idea: anyone downstream of it is forced to
801 manually fix their history. This section explains how to do the fix
802 from the downstream's point of view. The real fix, however, would be
803 to avoid rebasing the upstream in the first place.
804
805 To illustrate, suppose you are in a situation where someone develops a
806 'subsystem' branch, and you are working on a 'topic' that is dependent
807 on this 'subsystem'. You might end up with a history like the
808 following:
809
810 ------------
811 o---o---o---o---o---o---o---o master
812 \
813 o---o---o---o---o subsystem
814 \
815 *---*---* topic
816 ------------
817
818 If 'subsystem' is rebased against 'master', the following happens:
819
820 ------------
821 o---o---o---o---o---o---o---o master
822 \ \
823 o---o---o---o---o o'--o'--o'--o'--o' subsystem
824 \
825 *---*---* topic
826 ------------
827
828 If you now continue development as usual, and eventually merge 'topic'
829 to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
830
831 ------------
832 o---o---o---o---o---o---o---o master
833 \ \
834 o---o---o---o---o o'--o'--o'--o'--o'--M subsystem
835 \ /
836 *---*---*-..........-*--* topic
837 ------------
838
839 Such duplicates are generally frowned upon because they clutter up
840 history, making it harder to follow. To clean things up, you need to
841 transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
842 rebase 'topic'. This becomes a ripple effect: anyone downstream from
843 'topic' is forced to rebase too, and so on!
844
845 There are two kinds of fixes, discussed in the following subsections:
846
847 Easy case: The changes are literally the same.::
848
849 This happens if the 'subsystem' rebase was a simple rebase and
850 had no conflicts.
851
852 Hard case: The changes are not the same.::
853
854 This happens if the 'subsystem' rebase had conflicts, or used
855 `--interactive` to omit, edit, squash, or fixup commits; or
856 if the upstream used one of `commit --amend`, `reset`, or
857 a full history rewriting command like
858 https://github.com/newren/git-filter-repo[`filter-repo`].
859
860
861 The easy case
862 ~~~~~~~~~~~~~
863
864 Only works if the changes (patch IDs based on the diff contents) on
865 'subsystem' are literally the same before and after the rebase
866 'subsystem' did.
867
868 In that case, the fix is easy because 'git rebase' knows to skip
869 changes that are already present in the new upstream. So if you say
870 (assuming you're on 'topic')
871 ------------
872 $ git rebase subsystem
873 ------------
874 you will end up with the fixed history
875 ------------
876 o---o---o---o---o---o---o---o master
877 \
878 o'--o'--o'--o'--o' subsystem
879 \
880 *---*---* topic
881 ------------
882
883
884 The hard case
885 ~~~~~~~~~~~~~
886
887 Things get more complicated if the 'subsystem' changes do not exactly
888 correspond to the ones before the rebase.
889
890 NOTE: While an "easy case recovery" sometimes appears to be successful
891 even in the hard case, it may have unintended consequences. For
892 example, a commit that was removed via `git rebase
893 --interactive` will be **resurrected**!
894
895 The idea is to manually tell 'git rebase' "where the old 'subsystem'
896 ended and your 'topic' began", that is, what the old merge base
897 between them was. You will have to find a way to name the last commit
898 of the old 'subsystem', for example:
899
900 * With the 'subsystem' reflog: after 'git fetch', the old tip of
901 'subsystem' is at `subsystem@{1}`. Subsequent fetches will
902 increase the number. (See linkgit:git-reflog[1].)
903
904 * Relative to the tip of 'topic': knowing that your 'topic' has three
905 commits, the old tip of 'subsystem' must be `topic~3`.
906
907 You can then transplant the old `subsystem..topic` to the new tip by
908 saying (for the reflog case, and assuming you are on 'topic' already):
909 ------------
910 $ git rebase --onto subsystem subsystem@{1}
911 ------------
912
913 The ripple effect of a "hard case" recovery is especially bad:
914 'everyone' downstream from 'topic' will now have to perform a "hard
915 case" recovery too!
916
917 REBASING MERGES
918 ---------------
919
920 The interactive rebase command was originally designed to handle
921 individual patch series. As such, it makes sense to exclude merge
922 commits from the todo list, as the developer may have merged the
923 then-current `master` while working on the branch, only to rebase
924 all the commits onto `master` eventually (skipping the merge
925 commits).
926
927 However, there are legitimate reasons why a developer may want to
928 recreate merge commits: to keep the branch structure (or "commit
929 topology") when working on multiple, inter-related branches.
930
931 In the following example, the developer works on a topic branch that
932 refactors the way buttons are defined, and on another topic branch
933 that uses that refactoring to implement a "Report a bug" button. The
934 output of `git log --graph --format=%s -5` may look like this:
935
936 ------------
937 * Merge branch 'report-a-bug'
938 |\
939 | * Add the feedback button
940 * | Merge branch 'refactor-button'
941 |\ \
942 | |/
943 | * Use the Button class for all buttons
944 | * Extract a generic Button class from the DownloadButton one
945 ------------
946
947 The developer might want to rebase those commits to a newer `master`
948 while keeping the branch topology, for example when the first topic
949 branch is expected to be integrated into `master` much earlier than the
950 second one, say, to resolve merge conflicts with changes to the
951 DownloadButton class that made it into `master`.
952
953 This rebase can be performed using the `--rebase-merges` option.
954 It will generate a todo list looking like this:
955
956 ------------
957 label onto
958
959 # Branch: refactor-button
960 reset onto
961 pick 123456 Extract a generic Button class from the DownloadButton one
962 pick 654321 Use the Button class for all buttons
963 label refactor-button
964
965 # Branch: report-a-bug
966 reset refactor-button # Use the Button class for all buttons
967 pick abcdef Add the feedback button
968 label report-a-bug
969
970 reset onto
971 merge -C a1b2c3 refactor-button # Merge 'refactor-button'
972 merge -C 6f5e4d report-a-bug # Merge 'report-a-bug'
973 ------------
974
975 In contrast to a regular interactive rebase, there are `label`, `reset`
976 and `merge` commands in addition to `pick` ones.
977
978 The `label` command associates a label with the current HEAD when that
979 command is executed. These labels are created as worktree-local refs
980 (`refs/rewritten/<label>`) that will be deleted when the rebase
981 finishes. That way, rebase operations in multiple worktrees linked to
982 the same repository do not interfere with one another. If the `label`
983 command fails, it is rescheduled immediately, with a helpful message how
984 to proceed.
985
986 The `reset` command resets the HEAD, index and worktree to the specified
987 revision. It is similar to an `exec git reset --hard <label>`, but
988 refuses to overwrite untracked files. If the `reset` command fails, it is
989 rescheduled immediately, with a helpful message how to edit the todo list
990 (this typically happens when a `reset` command was inserted into the todo
991 list manually and contains a typo).
992
993 The `merge` command will merge the specified revision(s) into whatever
994 is HEAD at that time. With `-C <original-commit>`, the commit message of
995 the specified merge commit will be used. When the `-C` is changed to
996 a lower-case `-c`, the message will be opened in an editor after a
997 successful merge so that the user can edit the message.
998
999 If a `merge` command fails for any reason other than merge conflicts (i.e.
1000 when the merge operation did not even start), it is rescheduled immediately.
1001
1002 At this time, the `merge` command will *always* use the `recursive`
1003 merge strategy for regular merges, and `octopus` for octopus merges,
1004 with no way to choose a different one. To work around
1005 this, an `exec` command can be used to call `git merge` explicitly,
1006 using the fact that the labels are worktree-local refs (the ref
1007 `refs/rewritten/onto` would correspond to the label `onto`, for example).
1008
1009 Note: the first command (`label onto`) labels the revision onto which
1010 the commits are rebased; The name `onto` is just a convention, as a nod
1011 to the `--onto` option.
1012
1013 It is also possible to introduce completely new merge commits from scratch
1014 by adding a command of the form `merge <merge-head>`. This form will
1015 generate a tentative commit message and always open an editor to let the
1016 user edit it. This can be useful e.g. when a topic branch turns out to
1017 address more than a single concern and wants to be split into two or
1018 even more topic branches. Consider this todo list:
1019
1020 ------------
1021 pick 192837 Switch from GNU Makefiles to CMake
1022 pick 5a6c7e Document the switch to CMake
1023 pick 918273 Fix detection of OpenSSL in CMake
1024 pick afbecd http: add support for TLS v1.3
1025 pick fdbaec Fix detection of cURL in CMake on Windows
1026 ------------
1027
1028 The one commit in this list that is not related to CMake may very well
1029 have been motivated by working on fixing all those bugs introduced by
1030 switching to CMake, but it addresses a different concern. To split this
1031 branch into two topic branches, the todo list could be edited like this:
1032
1033 ------------
1034 label onto
1035
1036 pick afbecd http: add support for TLS v1.3
1037 label tlsv1.3
1038
1039 reset onto
1040 pick 192837 Switch from GNU Makefiles to CMake
1041 pick 918273 Fix detection of OpenSSL in CMake
1042 pick fdbaec Fix detection of cURL in CMake on Windows
1043 pick 5a6c7e Document the switch to CMake
1044 label cmake
1045
1046 reset onto
1047 merge tlsv1.3
1048 merge cmake
1049 ------------
1050
1051 BUGS
1052 ----
1053 The todo list presented by the deprecated `--preserve-merges --interactive`
1054 does not represent the topology of the revision graph (use `--rebase-merges`
1055 instead). Editing commits and rewording their commit messages should work
1056 fine, but attempts to reorder commits tend to produce counterintuitive results.
1057 Use `--rebase-merges` in such scenarios instead.
1058
1059 For example, an attempt to rearrange
1060 ------------
1061 1 --- 2 --- 3 --- 4 --- 5
1062 ------------
1063 to
1064 ------------
1065 1 --- 2 --- 4 --- 3 --- 5
1066 ------------
1067 by moving the "pick 4" line will result in the following history:
1068 ------------
1069 3
1070 /
1071 1 --- 2 --- 4 --- 5
1072 ------------
1073
1074 GIT
1075 ---
1076 Part of the linkgit:git[1] suite