rebase: teach rebase --keep-base
[git/git.git] / Documentation / git-rebase.txt
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1git-rebase(1)
2=============
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3
4NAME
5----
b385085b 6git-rebase - Reapply commits on top of another base tip
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7
8SYNOPSIS
9--------
e448ff87 10[verse]
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11'git rebase' [-i | --interactive] [<options>] [--exec <cmd>]
12 [--onto <newbase> | --keep-base] [<upstream> [<branch>]]
de613050 13'git rebase' [-i | --interactive] [<options>] [--exec <cmd>] [--onto <newbase>]
be496621 14 --root [<branch>]
437591a9 15'git rebase' (--continue | --skip | --abort | --quit | --edit-todo | --show-current-patch)
031321c6 16
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17DESCRIPTION
18-----------
0b444cdb 19If <branch> is specified, 'git rebase' will perform an automatic
328c6cb8 20`git switch <branch>` before doing anything else. Otherwise
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21it remains on the current branch.
22
15a147e6 23If <upstream> is not specified, the upstream configured in
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24branch.<name>.remote and branch.<name>.merge options will be used (see
25linkgit:git-config[1] for details) and the `--fork-point` option is
26assumed. If you are currently not on any branch or if the current
27branch does not have a configured upstream, the rebase will abort.
15a147e6 28
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29All changes made by commits in the current branch but that are not
30in <upstream> are saved to a temporary area. This is the same set
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31of commits that would be shown by `git log <upstream>..HEAD`; or by
32`git log 'fork_point'..HEAD`, if `--fork-point` is active (see the
33description on `--fork-point` below); or by `git log HEAD`, if the
34`--root` option is specified.
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35
36The current branch is reset to <upstream>, or <newbase> if the
37--onto option was supplied. This has the exact same effect as
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38`git reset --hard <upstream>` (or <newbase>). ORIG_HEAD is set
39to point at the tip of the branch before the reset.
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40
41The commits that were previously saved into the temporary area are
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42then reapplied to the current branch, one by one, in order. Note that
43any commits in HEAD which introduce the same textual changes as a commit
44in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream
45with a different commit message or timestamp will be skipped).
69a60af5 46
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47It is possible that a merge failure will prevent this process from being
48completely automatic. You will have to resolve any such merge failure
cc120056 49and run `git rebase --continue`. Another option is to bypass the commit
5960bc9d 50that caused the merge failure with `git rebase --skip`. To check out the
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51original <branch> and remove the .git/rebase-apply working files, use the
52command `git rebase --abort` instead.
031321c6 53
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54Assume the following history exists and the current branch is "topic":
55
031321c6 56------------
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57 A---B---C topic
58 /
59 D---E---F---G master
031321c6 60------------
69a60af5 61
228382ae 62From this point, the result of either of the following commands:
69a60af5 63
031321c6 64
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65 git rebase master
66 git rebase master topic
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67
68would be:
69
031321c6 70------------
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71 A'--B'--C' topic
72 /
73 D---E---F---G master
031321c6 74------------
69a60af5 75
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76*NOTE:* The latter form is just a short-hand of `git checkout topic`
77followed by `git rebase master`. When rebase exits `topic` will
78remain the checked-out branch.
69a60af5 79
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80If the upstream branch already contains a change you have made (e.g.,
81because you mailed a patch which was applied upstream), then that commit
b1889c36 82will be skipped. For example, running `git rebase master` on the
e08bc7a9 83following history (in which `A'` and `A` introduce the same set of changes,
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84but have different committer information):
85
86------------
87 A---B---C topic
88 /
89 D---E---A'---F master
90------------
91
92will result in:
93
94------------
95 B'---C' topic
96 /
97 D---E---A'---F master
98------------
99
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100Here is how you would transplant a topic branch based on one
101branch to another, to pretend that you forked the topic branch
102from the latter branch, using `rebase --onto`.
69a60af5 103
e52775f4 104First let's assume your 'topic' is based on branch 'next'.
e2b850b2 105For example, a feature developed in 'topic' depends on some
e52775f4 106functionality which is found in 'next'.
69a60af5 107
031321c6 108------------
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109 o---o---o---o---o master
110 \
111 o---o---o---o---o next
112 \
113 o---o---o topic
114------------
115
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116We want to make 'topic' forked from branch 'master'; for example,
117because the functionality on which 'topic' depends was merged into the
118more stable 'master' branch. We want our tree to look like this:
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119
120------------
121 o---o---o---o---o master
122 | \
123 | o'--o'--o' topic
124 \
125 o---o---o---o---o next
031321c6 126------------
7fc9d69f 127
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128We can get this using the following command:
129
b1889c36 130 git rebase --onto master next topic
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131
132
133Another example of --onto option is to rebase part of a
134branch. If we have the following situation:
135
136------------
137 H---I---J topicB
138 /
139 E---F---G topicA
140 /
141 A---B---C---D master
142------------
143
144then the command
145
b1889c36 146 git rebase --onto master topicA topicB
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147
148would result in:
149
150------------
151 H'--I'--J' topicB
152 /
153 | E---F---G topicA
154 |/
155 A---B---C---D master
156------------
157
158This is useful when topicB does not depend on topicA.
159
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160A range of commits could also be removed with rebase. If we have
161the following situation:
162
163------------
164 E---F---G---H---I---J topicA
165------------
166
167then the command
168
b1889c36 169 git rebase --onto topicA~5 topicA~3 topicA
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170
171would result in the removal of commits F and G:
172
173------------
174 E---H'---I'---J' topicA
175------------
176
177This is useful if F and G were flawed in some way, or should not be
178part of topicA. Note that the argument to --onto and the <upstream>
179parameter can be any valid commit-ish.
180
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181In case of conflict, 'git rebase' will stop at the first problematic commit
182and leave conflict markers in the tree. You can use 'git diff' to locate
031321c6 183the markers (<<<<<<) and make edits to resolve the conflict. For each
2de9b711 184file you edit, you need to tell Git that the conflict has been resolved,
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185typically this would be done with
186
187
d7f078b8 188 git add <filename>
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189
190
191After resolving the conflict manually and updating the index with the
192desired resolution, you can continue the rebasing process with
193
194
195 git rebase --continue
8978d043 196
8978d043 197
0b444cdb 198Alternatively, you can undo the 'git rebase' with
8978d043 199
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200
201 git rebase --abort
8978d043 202
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203CONFIGURATION
204-------------
205
c7245900 206include::config/rebase.txt[]
16cf51c7 207
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208OPTIONS
209-------
c2145384 210--onto <newbase>::
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211 Starting point at which to create the new commits. If the
212 --onto option is not specified, the starting point is
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213 <upstream>. May be any valid commit, and not just an
214 existing branch name.
873c3472 215+
b9190e79 216As a special case, you may use "A\...B" as a shortcut for the
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217merge base of A and B if there is exactly one merge base. You can
218leave out at most one of A and B, in which case it defaults to HEAD.
69a60af5 219
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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+
226This option is useful in the case where one is developing a feature on
227top of an upstream branch. While the feature is being worked on, the
228upstream branch may advance and it may not be the best idea to keep
229rebasing on top of the upstream but to keep the base commit as-is.
230+
231Although both this option and --fork-point find the merge base between
232<upstream> and <branch>, this option uses the merge base as the _starting
233point_ on which new commits will be created, whereas --fork-point uses
234the merge base to determine the _set of commits_ which will be rebased.
235+
236See also INCOMPATIBLE OPTIONS below.
237
52a22d1e 238<upstream>::
ea81fcc5 239 Upstream branch to compare against. May be any valid commit,
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240 not just an existing branch name. Defaults to the configured
241 upstream for the current branch.
7fc9d69f 242
228382ae 243<branch>::
52a22d1e 244 Working branch; defaults to HEAD.
7fc9d69f 245
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246--continue::
247 Restart the rebasing process after having resolved a merge conflict.
248
249--abort::
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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.
031321c6 255
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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
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261--keep-empty::
262 Keep the commits that do not change anything from its
263 parents in the result.
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264+
265See also INCOMPATIBLE OPTIONS below.
90e1818f 266
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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.
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271+
272See also INCOMPATIBLE OPTIONS below.
a6c612b5 273
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274--skip::
275 Restart the rebasing process by skipping the current patch.
58634dbf 276
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277--edit-todo::
278 Edit the todo list during an interactive rebase.
279
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280--show-current-patch::
281 Show the current patch in an interactive rebase or when rebase
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282 is stopped because of conflicts. This is the equivalent of
283 `git show REBASE_HEAD`.
66335298 284
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285-m::
286--merge::
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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.
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290+
291Note that a rebase merge works by replaying each commit from the working
292branch on top of the <upstream> branch. Because of this, when a merge
293conflict happens, the side reported as 'ours' is the so-far rebased
294series, starting with <upstream>, and 'theirs' is the working branch. In
295other words, the sides are swapped.
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296+
297See also INCOMPATIBLE OPTIONS below.
58634dbf 298
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299-s <strategy>::
300--strategy=<strategy>::
06f39190 301 Use the given merge strategy.
0b444cdb 302 If there is no `-s` option 'git merge-recursive' is used
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303 instead. This implies --merge.
304+
0b444cdb 305Because 'git rebase' replays each commit from the working branch
31ddd1ee 306on top of the <upstream> branch using the given strategy, using
5dacd4ab 307the 'ours' strategy simply empties all patches from the <branch>,
31ddd1ee 308which makes little sense.
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309+
310See also INCOMPATIBLE OPTIONS below.
58634dbf 311
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312-X <strategy-option>::
313--strategy-option=<strategy-option>::
314 Pass the <strategy-option> through to the merge strategy.
6cf378f0 315 This implies `--merge` and, if no strategy has been
93ce190c 316 specified, `-s recursive`. Note the reversal of 'ours' and
edfbbf7e 317 'theirs' as noted above for the `-m` option.
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318+
319See also INCOMPATIBLE OPTIONS below.
93ce190c 320
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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
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326-S[<keyid>]::
327--gpg-sign[=<keyid>]::
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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.
3ee5e540 331
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332-q::
333--quiet::
334 Be quiet. Implies --no-stat.
335
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336-v::
337--verbose::
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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.
b758789c 347
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348--no-verify::
349 This option bypasses the pre-rebase hook. See also linkgit:githooks[5].
350
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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
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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.
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360+
361See also INCOMPATIBLE OPTIONS below.
67dad687 362
983f464f 363--no-ff::
5e75d56f 364--force-rebase::
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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.
b4995494 369+
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370You may find this helpful after reverting a topic branch merge, as this option
371recreates the topic branch with fresh commits so it can be remerged
372successfully without needing to "revert the reversion" (see the
373link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for
374details).
5e75d56f 375
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376--fork-point::
377--no-fork-point::
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378 Use reflog to find a better common ancestor between <upstream>
379 and <branch> when calculating which commits have been
380 introduced by <branch>.
ad8261d2 381+
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382When --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'
386ends up being empty, the <upstream> will be used as a fallback.
387+
388If either <upstream> or --root is given on the command line, then the
389default is `--no-fork-point`, otherwise the default is `--fork-point`.
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390+
391If your branch was based on <upstream> but <upstream> was rewound and
392your branch contains commits which were dropped, this option can be used
393with `--keep-base` in order to drop those commits from your branch.
ad8261d2 394
86c91f91 395--ignore-whitespace::
749485f6 396--whitespace=<option>::
0b444cdb 397 These flag are passed to the 'git apply' program
5162e697 398 (see linkgit:git-apply[1]) that applies the patch.
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399+
400See also INCOMPATIBLE OPTIONS below.
059f446d 401
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402--committer-date-is-author-date::
403--ignore-date::
0b444cdb 404 These flags are passed to 'git am' to easily change the dates
570ccad3 405 of the rebased commits (see linkgit:git-am[1]).
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406+
407See also INCOMPATIBLE OPTIONS below.
570ccad3 408
9f79524a 409--signoff::
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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
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412 picked, edited or reworded will have the trailer added.
413+
414See also INCOMPATIBLE OPTIONS below.
9f79524a 415
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416-i::
417--interactive::
1b1dce4b 418 Make a list of the commits which are about to be rebased. Let the
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419 user edit that list before rebasing. This mode can also be used to
420 split commits (see SPLITTING COMMITS below).
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421+
422The commit list format can be changed by setting the configuration option
423rebase.instructionFormat. A customized instruction format will automatically
424have the long commit hash prepended to the format.
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425+
426See also INCOMPATIBLE OPTIONS below.
1b1dce4b 427
8f6aed71 428-r::
7543f6f4 429--rebase-merges[=(rebase-cousins|no-rebase-cousins)]::
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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+
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438By default, or when `no-rebase-cousins` was specified, commits which do not
439have `<upstream>` as direct ancestor will keep their original branch point,
dbf47215 440i.e. commits that would be excluded by linkgit:git-log[1]'s
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441`--ancestry-path` option will keep their original ancestry by default. If
442the `rebase-cousins` mode is turned on, such commits are instead rebased
443onto `<upstream>` (or `<onto>`, if specified).
444+
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445The `--rebase-merges` mode is similar in spirit to the deprecated
446`--preserve-merges`, but in contrast to that option works well in interactive
447rebases: commits can be reordered, inserted and dropped at will.
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448+
449It is currently only possible to recreate the merge commits using the
450`recursive` merge strategy; Different merge strategies can be used only via
451explicit `exec git merge -s <strategy> [...]` commands.
25cff9f1 452+
5dacd4ab 453See also REBASING MERGES and INCOMPATIBLE OPTIONS below.
8f6aed71 454
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455-p::
456--preserve-merges::
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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.
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461+
462This uses the `--interactive` machinery internally, but combining it
463with the `--interactive` option explicitly is generally not a good
464idea unless you know what you are doing (see BUGS below).
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465+
466See also INCOMPATIBLE OPTIONS below.
cddb42d2 467
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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
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472 commands. Any command that fails will interrupt the rebase,
473 with exit code 1.
c2145384 474+
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475You may execute several commands by either using one instance of `--exec`
476with several commands:
477+
478 git rebase -i --exec "cmd1 && cmd2 && ..."
479+
480or by giving more than one `--exec`:
481+
482 git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
483+
484If `--autosquash` is used, "exec" lines will not be appended for
485the intermediate commits, and will only appear at the end of each
486squash/fixup series.
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487+
488This uses the `--interactive` machinery internally, but it can be run
489without an explicit `--interactive`.
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490+
491See also INCOMPATIBLE OPTIONS below.
f09c9b8c 492
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493--root::
494 Rebase all commits reachable from <branch>, instead of
495 limiting them with an <upstream>. This allows you to rebase
df5df20c 496 the root commit(s) on a branch. When used with --onto, it
be496621 497 will skip changes already contained in <newbase> (instead of
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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
be496621 501 instead.
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502+
503See also INCOMPATIBLE OPTIONS below.
be496621 504
f59baa50 505--autosquash::
dd1e5b31 506--no-autosquash::
f59baa50 507 When the commit log message begins with "squash! ..." (or
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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].
f59baa50 517+
bcf9626a 518If the `--autosquash` option is enabled by default using the
da0005b8 519configuration variable `rebase.autoSquash`, this option can be
dd1e5b31 520used to override and disable this setting.
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521+
522See also INCOMPATIBLE OPTIONS below.
b4995494 523
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524--autostash::
525--no-autostash::
e01db917 526 Automatically create a temporary stash entry before the operation
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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
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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
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537INCOMPATIBLE OPTIONS
538--------------------
539
68aa495b 540The following options:
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541
542 * --committer-date-is-author-date
543 * --ignore-date
544 * --whitespace
545 * --ignore-whitespace
546 * -C
547
68aa495b 548are incompatible with the following options:
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549
550 * --merge
551 * --strategy
552 * --strategy-option
553 * --allow-empty-message
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554 * --[no-]autosquash
555 * --rebase-merges
556 * --preserve-merges
557 * --interactive
558 * --exec
559 * --keep-empty
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560 * --edit-todo
561 * --root when used in combination with --onto
562
68aa495b 563In addition, the following pairs of options are incompatible:
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564
565 * --preserve-merges and --interactive
566 * --preserve-merges and --signoff
567 * --preserve-merges and --rebase-merges
568 * --rebase-merges and --strategy
569 * --rebase-merges and --strategy-option
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570 * --keep-base and --onto
571 * --keep-base and --root
5dacd4ab 572
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573BEHAVIORAL DIFFERENCES
574-----------------------
575
6fcbad87 576There are some subtle differences how the backends behave.
0661e49a 577
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578Empty commits
579~~~~~~~~~~~~~
0661e49a 580
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581The am backend drops any "empty" commits, regardless of whether the
582commit started empty (had no changes relative to its parent to
583start with) or ended empty (all changes were already applied
584upstream in other commits).
0661e49a 585
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586The interactive backend drops commits by default that
587started empty and halts if it hits a commit that ended up empty.
588The `--keep-empty` option exists for the interactive backend to allow
589it to keep commits that started empty.
0661e49a 590
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591Directory rename detection
592~~~~~~~~~~~~~~~~~~~~~~~~~~
593
a8f5a590
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594Directory rename heuristics are enabled in the merge and interactive
595backends. Due to the lack of accurate tree information, directory
596rename detection is disabled in the am backend.
f59baa50 597
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598include::merge-strategies.txt[]
599
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600NOTES
601-----
90d1c08e 602
0b444cdb 603You should understand the implications of using 'git rebase' on a
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604repository that you share. See also RECOVERING FROM UPSTREAM REBASE
605below.
031321c6 606
467c0197 607When the git-rebase command is run, it will first execute a "pre-rebase"
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608hook if one exists. You can use this hook to do sanity checks and
609reject the rebase if it isn't appropriate. Please see the template
610pre-rebase hook script for an example.
611
702088af 612Upon completion, <branch> will be the current branch.
031321c6 613
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614INTERACTIVE MODE
615----------------
616
617Rebasing interactively means that you have a chance to edit the commits
618which are rebased. You can reorder the commits, and you can
619remove them (weeding out bad or otherwise unwanted patches).
620
621The interactive mode is meant for this type of workflow:
622
6231. have a wonderful idea
6242. hack on the code
6253. prepare a series for submission
6264. submit
627
628where point 2. consists of several instances of
629
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630a) regular use
631
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632 1. finish something worthy of a commit
633 2. commit
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634
635b) independent fixup
636
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637 1. realize that something does not work
638 2. fix that
639 3. commit it
640
641Sometimes the thing fixed in b.2. cannot be amended to the not-quite
642perfect commit it fixes, because that commit is buried deeply in a
643patch series. That is exactly what interactive rebase is for: use it
644after plenty of "a"s and "b"s, by rearranging and editing
645commits, and squashing multiple commits into one.
646
647Start it with the last commit you want to retain as-is:
648
649 git rebase -i <after-this-commit>
650
651An editor will be fired up with all the commits in your current branch
652(ignoring merge commits), which come after the given commit. You can
653reorder the commits in this list to your heart's content, and you can
654remove them. The list looks more or less like this:
655
656-------------------------------------------
657pick deadbee The oneline of this commit
658pick fa1afe1 The oneline of the next commit
659...
660-------------------------------------------
661
0b444cdb 662The oneline descriptions are purely for your pleasure; 'git rebase' will
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663not look at them but at the commit names ("deadbee" and "fa1afe1" in this
664example), so do not delete or edit the names.
665
666By replacing the command "pick" with the command "edit", you can tell
0b444cdb 667'git rebase' to stop after applying that commit, so that you can edit
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668the files and/or the commit message, amend the commit, and continue
669rebasing.
670
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671To interrupt the rebase (just like an "edit" command would do, but without
672cherry-picking any commit first), use the "break" command.
673
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674If you just want to edit the commit message for a commit, replace the
675command "pick" with the command "reword".
676
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677To drop a commit, replace the command "pick" with "drop", or just
678delete the matching line.
679
1b1dce4b 680If you want to fold two or more commits into one, replace the command
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681"pick" for the second and subsequent commits with "squash" or "fixup".
682If the commits had different authors, the folded commit will be
683attributed to the author of the first commit. The suggested commit
684message for the folded commit is the concatenation of the commit
685messages of the first commit and of those with the "squash" command,
686but omits the commit messages of commits with the "fixup" command.
1b1dce4b 687
0b444cdb 688'git rebase' will stop when "pick" has been replaced with "edit" or
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689when a command fails due to merge errors. When you are done editing
690and/or resolving conflicts you can continue with `git rebase --continue`.
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691
692For example, if you want to reorder the last 5 commits, such that what
693was HEAD~4 becomes the new HEAD. To achieve that, you would call
0b444cdb 694'git rebase' like this:
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695
696----------------------
697$ git rebase -i HEAD~5
698----------------------
699
700And move the first patch to the end of the list.
701
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702You might want to recreate merge commits, e.g. if you have a history
703like this:
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704
705------------------
706 X
707 \
708 A---M---B
709 /
710---o---O---P---Q
711------------------
712
713Suppose you want to rebase the side branch starting at "A" to "Q". Make
714sure that the current HEAD is "B", and call
715
716-----------------------------
7948b49a 717$ git rebase -i -r --onto Q O
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718-----------------------------
719
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720Reordering and editing commits usually creates untested intermediate
721steps. You may want to check that your history editing did not break
722anything by running a test, or at least recompiling at intermediate
723points in history by using the "exec" command (shortcut "x"). You may
724do so by creating a todo list like this one:
725
726-------------------------------------------
727pick deadbee Implement feature XXX
728fixup f1a5c00 Fix to feature XXX
729exec make
730pick c0ffeee The oneline of the next commit
731edit deadbab The oneline of the commit after
732exec cd subdir; make test
733...
734-------------------------------------------
735
736The interactive rebase will stop when a command fails (i.e. exits with
737non-0 status) to give you an opportunity to fix the problem. You can
738continue with `git rebase --continue`.
739
740The "exec" command launches the command in a shell (the one specified
741in `$SHELL`, or the default shell if `$SHELL` is not set), so you can
742use shell features (like "cd", ">", ";" ...). The command is run from
743the root of the working tree.
f0fd889d 744
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745----------------------------------
746$ git rebase -i --exec "make test"
747----------------------------------
748
749This command lets you check that intermediate commits are compilable.
750The todo list becomes like that:
751
752--------------------
753pick 5928aea one
754exec make test
755pick 04d0fda two
756exec make test
757pick ba46169 three
758exec make test
759pick f4593f9 four
760exec make test
761--------------------
762
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763SPLITTING COMMITS
764-----------------
765
766In interactive mode, you can mark commits with the action "edit". However,
0b444cdb 767this does not necessarily mean that 'git rebase' expects the result of this
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768edit to be exactly one commit. Indeed, you can undo the commit, or you can
769add other commits. This can be used to split a commit into two:
770
483bc4f0 771- Start an interactive rebase with `git rebase -i <commit>^`, where
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772 <commit> is the commit you want to split. In fact, any commit range
773 will do, as long as it contains that commit.
774
775- Mark the commit you want to split with the action "edit".
776
483bc4f0 777- When it comes to editing that commit, execute `git reset HEAD^`. The
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778 effect is that the HEAD is rewound by one, and the index follows suit.
779 However, the working tree stays the same.
780
781- Now add the changes to the index that you want to have in the first
483bc4f0 782 commit. You can use `git add` (possibly interactively) or
0b444cdb 783 'git gui' (or both) to do that.
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784
785- Commit the now-current index with whatever commit message is appropriate
786 now.
787
788- Repeat the last two steps until your working tree is clean.
789
483bc4f0 790- Continue the rebase with `git rebase --continue`.
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791
792If you are not absolutely sure that the intermediate revisions are
793consistent (they compile, pass the testsuite, etc.) you should use
0b444cdb 794'git stash' to stash away the not-yet-committed changes
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795after each commit, test, and amend the commit if fixes are necessary.
796
797
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798RECOVERING FROM UPSTREAM REBASE
799-------------------------------
800
801Rebasing (or any other form of rewriting) a branch that others have
802based work on is a bad idea: anyone downstream of it is forced to
803manually fix their history. This section explains how to do the fix
804from the downstream's point of view. The real fix, however, would be
805to avoid rebasing the upstream in the first place.
806
807To illustrate, suppose you are in a situation where someone develops a
808'subsystem' branch, and you are working on a 'topic' that is dependent
809on this 'subsystem'. You might end up with a history like the
810following:
811
812------------
01826066 813 o---o---o---o---o---o---o---o master
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814 \
815 o---o---o---o---o subsystem
816 \
817 *---*---* topic
818------------
819
820If 'subsystem' is rebased against 'master', the following happens:
821
822------------
823 o---o---o---o---o---o---o---o master
824 \ \
825 o---o---o---o---o o'--o'--o'--o'--o' subsystem
826 \
827 *---*---* topic
828------------
829
830If you now continue development as usual, and eventually merge 'topic'
831to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
832
833------------
834 o---o---o---o---o---o---o---o master
835 \ \
836 o---o---o---o---o o'--o'--o'--o'--o'--M subsystem
837 \ /
838 *---*---*-..........-*--* topic
839------------
840
841Such duplicates are generally frowned upon because they clutter up
842history, making it harder to follow. To clean things up, you need to
843transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
844rebase 'topic'. This becomes a ripple effect: anyone downstream from
845'topic' is forced to rebase too, and so on!
846
847There are two kinds of fixes, discussed in the following subsections:
848
849Easy case: The changes are literally the same.::
850
851 This happens if the 'subsystem' rebase was a simple rebase and
852 had no conflicts.
853
854Hard case: The changes are not the same.::
855
856 This happens if the 'subsystem' rebase had conflicts, or used
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857 `--interactive` to omit, edit, squash, or fixup commits; or
858 if the upstream used one of `commit --amend`, `reset`, or
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859 `filter-branch`.
860
861
862The easy case
863~~~~~~~~~~~~~
864
865Only works if the changes (patch IDs based on the diff contents) on
866'subsystem' are literally the same before and after the rebase
867'subsystem' did.
868
0b444cdb 869In that case, the fix is easy because 'git rebase' knows to skip
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870changes that are already present in the new upstream. So if you say
871(assuming you're on 'topic')
872------------
873 $ git rebase subsystem
874------------
875you will end up with the fixed history
876------------
877 o---o---o---o---o---o---o---o master
878 \
879 o'--o'--o'--o'--o' subsystem
880 \
881 *---*---* topic
882------------
883
884
885The hard case
886~~~~~~~~~~~~~
887
888Things get more complicated if the 'subsystem' changes do not exactly
889correspond to the ones before the rebase.
890
891NOTE: While an "easy case recovery" sometimes appears to be successful
892 even in the hard case, it may have unintended consequences. For
893 example, a commit that was removed via `git rebase
6cf378f0 894 --interactive` will be **resurrected**!
90d1c08e 895
0b444cdb 896The idea is to manually tell 'git rebase' "where the old 'subsystem'
414d924b 897ended and your 'topic' began", that is, what the old merge base
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898between them was. You will have to find a way to name the last commit
899of the old 'subsystem', for example:
900
0b444cdb 901* With the 'subsystem' reflog: after 'git fetch', the old tip of
6cf378f0 902 'subsystem' is at `subsystem@{1}`. Subsequent fetches will
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903 increase the number. (See linkgit:git-reflog[1].)
904
905* Relative to the tip of 'topic': knowing that your 'topic' has three
906 commits, the old tip of 'subsystem' must be `topic~3`.
907
908You can then transplant the old `subsystem..topic` to the new tip by
909saying (for the reflog case, and assuming you are on 'topic' already):
910------------
911 $ git rebase --onto subsystem subsystem@{1}
912------------
913
914The ripple effect of a "hard case" recovery is especially bad:
915'everyone' downstream from 'topic' will now have to perform a "hard
916case" recovery too!
917
25cff9f1 918REBASING MERGES
81d395cc 919---------------
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920
921The interactive rebase command was originally designed to handle
922individual patch series. As such, it makes sense to exclude merge
923commits from the todo list, as the developer may have merged the
924then-current `master` while working on the branch, only to rebase
925all the commits onto `master` eventually (skipping the merge
926commits).
927
928However, there are legitimate reasons why a developer may want to
929recreate merge commits: to keep the branch structure (or "commit
930topology") when working on multiple, inter-related branches.
931
932In the following example, the developer works on a topic branch that
933refactors the way buttons are defined, and on another topic branch
934that uses that refactoring to implement a "Report a bug" button. The
935output of `git log --graph --format=%s -5` may look like this:
936
937------------
938* Merge branch 'report-a-bug'
939|\
940| * Add the feedback button
941* | Merge branch 'refactor-button'
942|\ \
943| |/
944| * Use the Button class for all buttons
945| * Extract a generic Button class from the DownloadButton one
946------------
947
948The developer might want to rebase those commits to a newer `master`
949while keeping the branch topology, for example when the first topic
950branch is expected to be integrated into `master` much earlier than the
951second one, say, to resolve merge conflicts with changes to the
952DownloadButton class that made it into `master`.
953
954This rebase can be performed using the `--rebase-merges` option.
955It will generate a todo list looking like this:
956
957------------
958label onto
959
960# Branch: refactor-button
961reset onto
962pick 123456 Extract a generic Button class from the DownloadButton one
963pick 654321 Use the Button class for all buttons
964label refactor-button
965
966# Branch: report-a-bug
967reset refactor-button # Use the Button class for all buttons
968pick abcdef Add the feedback button
969label report-a-bug
970
971reset onto
972merge -C a1b2c3 refactor-button # Merge 'refactor-button'
973merge -C 6f5e4d report-a-bug # Merge 'report-a-bug'
974------------
975
976In contrast to a regular interactive rebase, there are `label`, `reset`
977and `merge` commands in addition to `pick` ones.
978
979The `label` command associates a label with the current HEAD when that
980command is executed. These labels are created as worktree-local refs
981(`refs/rewritten/<label>`) that will be deleted when the rebase
982finishes. That way, rebase operations in multiple worktrees linked to
983the same repository do not interfere with one another. If the `label`
984command fails, it is rescheduled immediately, with a helpful message how
985to proceed.
986
987The `reset` command resets the HEAD, index and worktree to the specified
ad0b8f95 988revision. It is similar to an `exec git reset --hard <label>`, but
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989refuses to overwrite untracked files. If the `reset` command fails, it is
990rescheduled immediately, with a helpful message how to edit the todo list
991(this typically happens when a `reset` command was inserted into the todo
992list manually and contains a typo).
993
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994The `merge` command will merge the specified revision(s) into whatever
995is HEAD at that time. With `-C <original-commit>`, the commit message of
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996the specified merge commit will be used. When the `-C` is changed to
997a lower-case `-c`, the message will be opened in an editor after a
998successful merge so that the user can edit the message.
999
1000If a `merge` command fails for any reason other than merge conflicts (i.e.
1001when the merge operation did not even start), it is rescheduled immediately.
1002
1003At this time, the `merge` command will *always* use the `recursive`
caafecfc 1004merge strategy for regular merges, and `octopus` for octopus merges,
57e9dcaa 1005with no way to choose a different one. To work around
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1006this, an `exec` command can be used to call `git merge` explicitly,
1007using the fact that the labels are worktree-local refs (the ref
1008`refs/rewritten/onto` would correspond to the label `onto`, for example).
1009
1010Note: the first command (`label onto`) labels the revision onto which
1011the commits are rebased; The name `onto` is just a convention, as a nod
1012to the `--onto` option.
1013
1014It is also possible to introduce completely new merge commits from scratch
1015by adding a command of the form `merge <merge-head>`. This form will
1016generate a tentative commit message and always open an editor to let the
1017user edit it. This can be useful e.g. when a topic branch turns out to
1018address more than a single concern and wants to be split into two or
1019even more topic branches. Consider this todo list:
1020
1021------------
1022pick 192837 Switch from GNU Makefiles to CMake
1023pick 5a6c7e Document the switch to CMake
1024pick 918273 Fix detection of OpenSSL in CMake
1025pick afbecd http: add support for TLS v1.3
1026pick fdbaec Fix detection of cURL in CMake on Windows
1027------------
1028
1029The one commit in this list that is not related to CMake may very well
1030have been motivated by working on fixing all those bugs introduced by
1031switching to CMake, but it addresses a different concern. To split this
1032branch into two topic branches, the todo list could be edited like this:
1033
1034------------
1035label onto
1036
1037pick afbecd http: add support for TLS v1.3
1038label tlsv1.3
1039
1040reset onto
1041pick 192837 Switch from GNU Makefiles to CMake
1042pick 918273 Fix detection of OpenSSL in CMake
1043pick fdbaec Fix detection of cURL in CMake on Windows
1044pick 5a6c7e Document the switch to CMake
1045label cmake
1046
1047reset onto
1048merge tlsv1.3
1049merge cmake
1050------------
1051
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1052BUGS
1053----
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1054The todo list presented by the deprecated `--preserve-merges --interactive`
1055does not represent the topology of the revision graph (use `--rebase-merges`
1056instead). Editing commits and rewording their commit messages should work
1057fine, but attempts to reorder commits tend to produce counterintuitive results.
1058Use `--rebase-merges` in such scenarios instead.
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1059
1060For example, an attempt to rearrange
1061------------
10621 --- 2 --- 3 --- 4 --- 5
1063------------
1064to
1065------------
10661 --- 2 --- 4 --- 3 --- 5
1067------------
1068by moving the "pick 4" line will result in the following history:
1069------------
1070 3
1071 /
10721 --- 2 --- 4 --- 5
1073------------
1074
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1075GIT
1076---
9e1f0a85 1077Part of the linkgit:git[1] suite