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215a7ad1 JH |
1 | git-rebase(1) |
2 | ============= | |
7fc9d69f JH |
3 | |
4 | NAME | |
5 | ---- | |
c3f0baac | 6 | git-rebase - Forward-port local commits to the updated upstream head |
7fc9d69f JH |
7 | |
8 | SYNOPSIS | |
9 | -------- | |
e448ff87 | 10 | [verse] |
be496621 TR |
11 | 'git rebase' [-i | --interactive] [options] [--onto <newbase>] |
12 | <upstream> [<branch>] | |
13 | 'git rebase' [-i | --interactive] [options] --onto <newbase> | |
14 | --root [<branch>] | |
15 | ||
b1889c36 | 16 | 'git rebase' --continue | --skip | --abort |
031321c6 | 17 | |
7fc9d69f JH |
18 | DESCRIPTION |
19 | ----------- | |
0b444cdb | 20 | If <branch> is specified, 'git rebase' will perform an automatic |
5ca2db53 SP |
21 | `git checkout <branch>` before doing anything else. Otherwise |
22 | it remains on the current branch. | |
23 | ||
24 | All changes made by commits in the current branch but that are not | |
25 | in <upstream> are saved to a temporary area. This is the same set | |
be496621 TR |
26 | of commits that would be shown by `git log <upstream>..HEAD` (or |
27 | `git log HEAD`, if --root is specified). | |
5ca2db53 SP |
28 | |
29 | The current branch is reset to <upstream>, or <newbase> if the | |
30 | --onto option was supplied. This has the exact same effect as | |
9869099b BG |
31 | `git reset --hard <upstream>` (or <newbase>). ORIG_HEAD is set |
32 | to point at the tip of the branch before the reset. | |
5ca2db53 SP |
33 | |
34 | The commits that were previously saved into the temporary area are | |
ff905462 JK |
35 | then reapplied to the current branch, one by one, in order. Note that |
36 | any commits in HEAD which introduce the same textual changes as a commit | |
37 | in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream | |
38 | with a different commit message or timestamp will be skipped). | |
69a60af5 | 39 | |
031321c6 SE |
40 | It is possible that a merge failure will prevent this process from being |
41 | completely automatic. You will have to resolve any such merge failure | |
cc120056 SE |
42 | and run `git rebase --continue`. Another option is to bypass the commit |
43 | that caused the merge failure with `git rebase --skip`. To restore the | |
51ef1daa JS |
44 | original <branch> and remove the .git/rebase-apply working files, use the |
45 | command `git rebase --abort` instead. | |
031321c6 | 46 | |
69a60af5 CW |
47 | Assume the following history exists and the current branch is "topic": |
48 | ||
031321c6 | 49 | ------------ |
69a60af5 CW |
50 | A---B---C topic |
51 | / | |
52 | D---E---F---G master | |
031321c6 | 53 | ------------ |
69a60af5 | 54 | |
228382ae | 55 | From this point, the result of either of the following commands: |
69a60af5 | 56 | |
031321c6 | 57 | |
b1889c36 JN |
58 | git rebase master |
59 | git rebase master topic | |
69a60af5 CW |
60 | |
61 | would be: | |
62 | ||
031321c6 | 63 | ------------ |
69a60af5 CW |
64 | A'--B'--C' topic |
65 | / | |
66 | D---E---F---G master | |
031321c6 | 67 | ------------ |
69a60af5 | 68 | |
e52775f4 JN |
69 | The latter form is just a short-hand of `git checkout topic` |
70 | followed by `git rebase master`. | |
69a60af5 | 71 | |
ff905462 JK |
72 | If the upstream branch already contains a change you have made (e.g., |
73 | because you mailed a patch which was applied upstream), then that commit | |
b1889c36 | 74 | will be skipped. For example, running `git rebase master` on the |
ff905462 JK |
75 | following history (in which A' and A introduce the same set of changes, |
76 | but have different committer information): | |
77 | ||
78 | ------------ | |
79 | A---B---C topic | |
80 | / | |
81 | D---E---A'---F master | |
82 | ------------ | |
83 | ||
84 | will result in: | |
85 | ||
86 | ------------ | |
87 | B'---C' topic | |
88 | / | |
89 | D---E---A'---F master | |
90 | ------------ | |
91 | ||
e52775f4 JN |
92 | Here is how you would transplant a topic branch based on one |
93 | branch to another, to pretend that you forked the topic branch | |
94 | from the latter branch, using `rebase --onto`. | |
69a60af5 | 95 | |
e52775f4 | 96 | First let's assume your 'topic' is based on branch 'next'. |
e2b850b2 | 97 | For example, a feature developed in 'topic' depends on some |
e52775f4 | 98 | functionality which is found in 'next'. |
69a60af5 | 99 | |
031321c6 | 100 | ------------ |
e52775f4 JN |
101 | o---o---o---o---o master |
102 | \ | |
103 | o---o---o---o---o next | |
104 | \ | |
105 | o---o---o topic | |
106 | ------------ | |
107 | ||
e2b850b2 GD |
108 | We want to make 'topic' forked from branch 'master'; for example, |
109 | because the functionality on which 'topic' depends was merged into the | |
110 | more stable 'master' branch. We want our tree to look like this: | |
e52775f4 JN |
111 | |
112 | ------------ | |
113 | o---o---o---o---o master | |
114 | | \ | |
115 | | o'--o'--o' topic | |
116 | \ | |
117 | o---o---o---o---o next | |
031321c6 | 118 | ------------ |
7fc9d69f | 119 | |
e52775f4 JN |
120 | We can get this using the following command: |
121 | ||
b1889c36 | 122 | git rebase --onto master next topic |
e52775f4 JN |
123 | |
124 | ||
125 | Another example of --onto option is to rebase part of a | |
126 | branch. If we have the following situation: | |
127 | ||
128 | ------------ | |
129 | H---I---J topicB | |
130 | / | |
131 | E---F---G topicA | |
132 | / | |
133 | A---B---C---D master | |
134 | ------------ | |
135 | ||
136 | then the command | |
137 | ||
b1889c36 | 138 | git rebase --onto master topicA topicB |
e52775f4 JN |
139 | |
140 | would result in: | |
141 | ||
142 | ------------ | |
143 | H'--I'--J' topicB | |
144 | / | |
145 | | E---F---G topicA | |
146 | |/ | |
147 | A---B---C---D master | |
148 | ------------ | |
149 | ||
150 | This is useful when topicB does not depend on topicA. | |
151 | ||
ea81fcc5 SP |
152 | A range of commits could also be removed with rebase. If we have |
153 | the following situation: | |
154 | ||
155 | ------------ | |
156 | E---F---G---H---I---J topicA | |
157 | ------------ | |
158 | ||
159 | then the command | |
160 | ||
b1889c36 | 161 | git rebase --onto topicA~5 topicA~3 topicA |
ea81fcc5 SP |
162 | |
163 | would result in the removal of commits F and G: | |
164 | ||
165 | ------------ | |
166 | E---H'---I'---J' topicA | |
167 | ------------ | |
168 | ||
169 | This is useful if F and G were flawed in some way, or should not be | |
170 | part of topicA. Note that the argument to --onto and the <upstream> | |
171 | parameter can be any valid commit-ish. | |
172 | ||
0b444cdb TR |
173 | In case of conflict, 'git rebase' will stop at the first problematic commit |
174 | and leave conflict markers in the tree. You can use 'git diff' to locate | |
031321c6 SE |
175 | the markers (<<<<<<) and make edits to resolve the conflict. For each |
176 | file you edit, you need to tell git that the conflict has been resolved, | |
177 | typically this would be done with | |
178 | ||
179 | ||
d7f078b8 | 180 | git add <filename> |
031321c6 SE |
181 | |
182 | ||
183 | After resolving the conflict manually and updating the index with the | |
184 | desired resolution, you can continue the rebasing process with | |
185 | ||
186 | ||
187 | git rebase --continue | |
8978d043 | 188 | |
8978d043 | 189 | |
0b444cdb | 190 | Alternatively, you can undo the 'git rebase' with |
8978d043 | 191 | |
031321c6 SE |
192 | |
193 | git rebase --abort | |
8978d043 | 194 | |
a9c3821c TAV |
195 | CONFIGURATION |
196 | ------------- | |
197 | ||
198 | rebase.stat:: | |
199 | Whether to show a diffstat of what changed upstream since the last | |
200 | rebase. False by default. | |
201 | ||
dd1e5b31 HV |
202 | rebase.autosquash:: |
203 | If set to true enable '--autosquash' option by default. | |
204 | ||
7fc9d69f JH |
205 | OPTIONS |
206 | ------- | |
69a60af5 CW |
207 | <newbase>:: |
208 | Starting point at which to create the new commits. If the | |
209 | --onto option is not specified, the starting point is | |
ea81fcc5 SP |
210 | <upstream>. May be any valid commit, and not just an |
211 | existing branch name. | |
873c3472 | 212 | + |
b9190e79 | 213 | As a special case, you may use "A\...B" as a shortcut for the |
873c3472 MG |
214 | merge base of A and B if there is exactly one merge base. You can |
215 | leave out at most one of A and B, in which case it defaults to HEAD. | |
69a60af5 | 216 | |
52a22d1e | 217 | <upstream>:: |
ea81fcc5 SP |
218 | Upstream branch to compare against. May be any valid commit, |
219 | not just an existing branch name. | |
7fc9d69f | 220 | |
228382ae | 221 | <branch>:: |
52a22d1e | 222 | Working branch; defaults to HEAD. |
7fc9d69f | 223 | |
031321c6 SE |
224 | --continue:: |
225 | Restart the rebasing process after having resolved a merge conflict. | |
226 | ||
227 | --abort:: | |
228 | Restore the original branch and abort the rebase operation. | |
229 | ||
58634dbf EW |
230 | --skip:: |
231 | Restart the rebasing process by skipping the current patch. | |
58634dbf | 232 | |
3240240f SB |
233 | -m:: |
234 | --merge:: | |
58634dbf EW |
235 | Use merging strategies to rebase. When the recursive (default) merge |
236 | strategy is used, this allows rebase to be aware of renames on the | |
237 | upstream side. | |
31ddd1ee TR |
238 | + |
239 | Note that a rebase merge works by replaying each commit from the working | |
240 | branch on top of the <upstream> branch. Because of this, when a merge | |
241 | conflict happens, the side reported as 'ours' is the so-far rebased | |
242 | series, starting with <upstream>, and 'theirs' is the working branch. In | |
243 | other words, the sides are swapped. | |
58634dbf | 244 | |
3240240f SB |
245 | -s <strategy>:: |
246 | --strategy=<strategy>:: | |
06f39190 | 247 | Use the given merge strategy. |
0b444cdb | 248 | If there is no `-s` option 'git merge-recursive' is used |
31ddd1ee TR |
249 | instead. This implies --merge. |
250 | + | |
0b444cdb | 251 | Because 'git rebase' replays each commit from the working branch |
31ddd1ee TR |
252 | on top of the <upstream> branch using the given strategy, using |
253 | the 'ours' strategy simply discards all patches from the <branch>, | |
254 | which makes little sense. | |
58634dbf | 255 | |
93ce190c ML |
256 | -X <strategy-option>:: |
257 | --strategy-option=<strategy-option>:: | |
258 | Pass the <strategy-option> through to the merge strategy. | |
259 | This implies `\--merge` and, if no strategy has been | |
260 | specified, `-s recursive`. Note the reversal of 'ours' and | |
261 | 'theirs' as noted in above for the `-m` option. | |
262 | ||
0e987a12 SB |
263 | -q:: |
264 | --quiet:: | |
265 | Be quiet. Implies --no-stat. | |
266 | ||
3240240f SB |
267 | -v:: |
268 | --verbose:: | |
a9c3821c TAV |
269 | Be verbose. Implies --stat. |
270 | ||
271 | --stat:: | |
272 | Show a diffstat of what changed upstream since the last rebase. The | |
273 | diffstat is also controlled by the configuration option rebase.stat. | |
274 | ||
275 | -n:: | |
276 | --no-stat:: | |
277 | Do not show a diffstat as part of the rebase process. | |
b758789c | 278 | |
fd631d58 NS |
279 | --no-verify:: |
280 | This option bypasses the pre-rebase hook. See also linkgit:githooks[5]. | |
281 | ||
7baf9c4b MZ |
282 | --verify:: |
283 | Allows the pre-rebase hook to run, which is the default. This option can | |
284 | be used to override --no-verify. See also linkgit:githooks[5]. | |
285 | ||
67dad687 MT |
286 | -C<n>:: |
287 | Ensure at least <n> lines of surrounding context match before | |
288 | and after each change. When fewer lines of surrounding | |
289 | context exist they all must match. By default no context is | |
290 | ever ignored. | |
291 | ||
5e75d56f MB |
292 | -f:: |
293 | --force-rebase:: | |
294 | Force the rebase even if the current branch is a descendant | |
b4995494 | 295 | of the commit you are rebasing onto. Normally non-interactive rebase will |
5e75d56f MB |
296 | exit with the message "Current branch is up to date" in such a |
297 | situation. | |
b4995494 MB |
298 | Incompatible with the --interactive option. |
299 | + | |
300 | You may find this (or --no-ff with an interactive rebase) helpful after | |
301 | reverting a topic branch merge, as this option recreates the topic branch with | |
302 | fresh commits so it can be remerged successfully without needing to "revert | |
303 | the reversion" (see the | |
304 | link:howto/revert-a-faulty-merge.txt[revert-a-faulty-merge How-To] for details). | |
5e75d56f | 305 | |
86c91f91 | 306 | --ignore-whitespace:: |
749485f6 | 307 | --whitespace=<option>:: |
0b444cdb | 308 | These flag are passed to the 'git apply' program |
5162e697 | 309 | (see linkgit:git-apply[1]) that applies the patch. |
7fe54385 | 310 | Incompatible with the --interactive option. |
059f446d | 311 | |
570ccad3 MB |
312 | --committer-date-is-author-date:: |
313 | --ignore-date:: | |
0b444cdb | 314 | These flags are passed to 'git am' to easily change the dates |
570ccad3 | 315 | of the rebased commits (see linkgit:git-am[1]). |
56a05720 | 316 | Incompatible with the --interactive option. |
570ccad3 | 317 | |
3240240f SB |
318 | -i:: |
319 | --interactive:: | |
1b1dce4b | 320 | Make a list of the commits which are about to be rebased. Let the |
f0fd889d JS |
321 | user edit that list before rebasing. This mode can also be used to |
322 | split commits (see SPLITTING COMMITS below). | |
1b1dce4b | 323 | |
3240240f SB |
324 | -p:: |
325 | --preserve-merges:: | |
f8cca019 | 326 | Instead of ignoring merges, try to recreate them. |
cddb42d2 JN |
327 | + |
328 | This uses the `--interactive` machinery internally, but combining it | |
329 | with the `--interactive` option explicitly is generally not a good | |
330 | idea unless you know what you are doing (see BUGS below). | |
331 | ||
f09c9b8c | 332 | |
be496621 TR |
333 | --root:: |
334 | Rebase all commits reachable from <branch>, instead of | |
335 | limiting them with an <upstream>. This allows you to rebase | |
336 | the root commit(s) on a branch. Must be used with --onto, and | |
337 | will skip changes already contained in <newbase> (instead of | |
338 | <upstream>). When used together with --preserve-merges, 'all' | |
339 | root commits will be rewritten to have <newbase> as parent | |
340 | instead. | |
341 | ||
f59baa50 | 342 | --autosquash:: |
dd1e5b31 | 343 | --no-autosquash:: |
f59baa50 NS |
344 | When the commit log message begins with "squash! ..." (or |
345 | "fixup! ..."), and there is a commit whose title begins with | |
346 | the same ..., automatically modify the todo list of rebase -i | |
42cfcd20 | 347 | so that the commit marked for squashing comes right after the |
f59baa50 NS |
348 | commit to be modified, and change the action of the moved |
349 | commit from `pick` to `squash` (or `fixup`). | |
350 | + | |
b4995494 | 351 | This option is only valid when the '--interactive' option is used. |
dd1e5b31 HV |
352 | + |
353 | If the '--autosquash' option is enabled by default using the | |
354 | configuration variable `rebase.autosquash`, this option can be | |
355 | used to override and disable this setting. | |
b4995494 MB |
356 | |
357 | --no-ff:: | |
358 | With --interactive, cherry-pick all rebased commits instead of | |
359 | fast-forwarding over the unchanged ones. This ensures that the | |
360 | entire history of the rebased branch is composed of new commits. | |
361 | + | |
362 | Without --interactive, this is a synonym for --force-rebase. | |
363 | + | |
364 | You may find this helpful after reverting a topic branch merge, as this option | |
365 | recreates the topic branch with fresh commits so it can be remerged | |
366 | successfully without needing to "revert the reversion" (see the | |
367 | link:howto/revert-a-faulty-merge.txt[revert-a-faulty-merge How-To] for details). | |
f59baa50 | 368 | |
58634dbf EW |
369 | include::merge-strategies.txt[] |
370 | ||
031321c6 SE |
371 | NOTES |
372 | ----- | |
90d1c08e | 373 | |
0b444cdb | 374 | You should understand the implications of using 'git rebase' on a |
90d1c08e TR |
375 | repository that you share. See also RECOVERING FROM UPSTREAM REBASE |
376 | below. | |
031321c6 | 377 | |
467c0197 | 378 | When the git-rebase command is run, it will first execute a "pre-rebase" |
031321c6 SE |
379 | hook if one exists. You can use this hook to do sanity checks and |
380 | reject the rebase if it isn't appropriate. Please see the template | |
381 | pre-rebase hook script for an example. | |
382 | ||
702088af | 383 | Upon completion, <branch> will be the current branch. |
031321c6 | 384 | |
1b1dce4b JS |
385 | INTERACTIVE MODE |
386 | ---------------- | |
387 | ||
388 | Rebasing interactively means that you have a chance to edit the commits | |
389 | which are rebased. You can reorder the commits, and you can | |
390 | remove them (weeding out bad or otherwise unwanted patches). | |
391 | ||
392 | The interactive mode is meant for this type of workflow: | |
393 | ||
394 | 1. have a wonderful idea | |
395 | 2. hack on the code | |
396 | 3. prepare a series for submission | |
397 | 4. submit | |
398 | ||
399 | where point 2. consists of several instances of | |
400 | ||
401 | a. regular use | |
402 | 1. finish something worthy of a commit | |
403 | 2. commit | |
404 | b. independent fixup | |
405 | 1. realize that something does not work | |
406 | 2. fix that | |
407 | 3. commit it | |
408 | ||
409 | Sometimes the thing fixed in b.2. cannot be amended to the not-quite | |
410 | perfect commit it fixes, because that commit is buried deeply in a | |
411 | patch series. That is exactly what interactive rebase is for: use it | |
412 | after plenty of "a"s and "b"s, by rearranging and editing | |
413 | commits, and squashing multiple commits into one. | |
414 | ||
415 | Start it with the last commit you want to retain as-is: | |
416 | ||
417 | git rebase -i <after-this-commit> | |
418 | ||
419 | An editor will be fired up with all the commits in your current branch | |
420 | (ignoring merge commits), which come after the given commit. You can | |
421 | reorder the commits in this list to your heart's content, and you can | |
422 | remove them. The list looks more or less like this: | |
423 | ||
424 | ------------------------------------------- | |
425 | pick deadbee The oneline of this commit | |
426 | pick fa1afe1 The oneline of the next commit | |
427 | ... | |
428 | ------------------------------------------- | |
429 | ||
0b444cdb | 430 | The oneline descriptions are purely for your pleasure; 'git rebase' will |
1b1dce4b JS |
431 | not look at them but at the commit names ("deadbee" and "fa1afe1" in this |
432 | example), so do not delete or edit the names. | |
433 | ||
434 | By replacing the command "pick" with the command "edit", you can tell | |
0b444cdb | 435 | 'git rebase' to stop after applying that commit, so that you can edit |
1b1dce4b JS |
436 | the files and/or the commit message, amend the commit, and continue |
437 | rebasing. | |
438 | ||
6741aa6c BG |
439 | If you just want to edit the commit message for a commit, replace the |
440 | command "pick" with the command "reword". | |
441 | ||
1b1dce4b | 442 | If you want to fold two or more commits into one, replace the command |
0205e72f MH |
443 | "pick" for the second and subsequent commits with "squash" or "fixup". |
444 | If the commits had different authors, the folded commit will be | |
445 | attributed to the author of the first commit. The suggested commit | |
446 | message for the folded commit is the concatenation of the commit | |
447 | messages of the first commit and of those with the "squash" command, | |
448 | but omits the commit messages of commits with the "fixup" command. | |
1b1dce4b | 449 | |
0b444cdb | 450 | 'git rebase' will stop when "pick" has been replaced with "edit" or |
6741aa6c BG |
451 | when a command fails due to merge errors. When you are done editing |
452 | and/or resolving conflicts you can continue with `git rebase --continue`. | |
1b1dce4b JS |
453 | |
454 | For example, if you want to reorder the last 5 commits, such that what | |
455 | was HEAD~4 becomes the new HEAD. To achieve that, you would call | |
0b444cdb | 456 | 'git rebase' like this: |
1b1dce4b JS |
457 | |
458 | ---------------------- | |
459 | $ git rebase -i HEAD~5 | |
460 | ---------------------- | |
461 | ||
462 | And move the first patch to the end of the list. | |
463 | ||
f09c9b8c JS |
464 | You might want to preserve merges, if you have a history like this: |
465 | ||
466 | ------------------ | |
467 | X | |
468 | \ | |
469 | A---M---B | |
470 | / | |
471 | ---o---O---P---Q | |
472 | ------------------ | |
473 | ||
474 | Suppose you want to rebase the side branch starting at "A" to "Q". Make | |
475 | sure that the current HEAD is "B", and call | |
476 | ||
477 | ----------------------------- | |
478 | $ git rebase -i -p --onto Q O | |
479 | ----------------------------- | |
480 | ||
cd035b1c MM |
481 | Reordering and editing commits usually creates untested intermediate |
482 | steps. You may want to check that your history editing did not break | |
483 | anything by running a test, or at least recompiling at intermediate | |
484 | points in history by using the "exec" command (shortcut "x"). You may | |
485 | do so by creating a todo list like this one: | |
486 | ||
487 | ------------------------------------------- | |
488 | pick deadbee Implement feature XXX | |
489 | fixup f1a5c00 Fix to feature XXX | |
490 | exec make | |
491 | pick c0ffeee The oneline of the next commit | |
492 | edit deadbab The oneline of the commit after | |
493 | exec cd subdir; make test | |
494 | ... | |
495 | ------------------------------------------- | |
496 | ||
497 | The interactive rebase will stop when a command fails (i.e. exits with | |
498 | non-0 status) to give you an opportunity to fix the problem. You can | |
499 | continue with `git rebase --continue`. | |
500 | ||
501 | The "exec" command launches the command in a shell (the one specified | |
502 | in `$SHELL`, or the default shell if `$SHELL` is not set), so you can | |
503 | use shell features (like "cd", ">", ";" ...). The command is run from | |
504 | the root of the working tree. | |
f0fd889d JS |
505 | |
506 | SPLITTING COMMITS | |
507 | ----------------- | |
508 | ||
509 | In interactive mode, you can mark commits with the action "edit". However, | |
0b444cdb | 510 | this does not necessarily mean that 'git rebase' expects the result of this |
f0fd889d JS |
511 | edit to be exactly one commit. Indeed, you can undo the commit, or you can |
512 | add other commits. This can be used to split a commit into two: | |
513 | ||
483bc4f0 | 514 | - Start an interactive rebase with `git rebase -i <commit>^`, where |
f0fd889d JS |
515 | <commit> is the commit you want to split. In fact, any commit range |
516 | will do, as long as it contains that commit. | |
517 | ||
518 | - Mark the commit you want to split with the action "edit". | |
519 | ||
483bc4f0 | 520 | - When it comes to editing that commit, execute `git reset HEAD^`. The |
f0fd889d JS |
521 | effect is that the HEAD is rewound by one, and the index follows suit. |
522 | However, the working tree stays the same. | |
523 | ||
524 | - Now add the changes to the index that you want to have in the first | |
483bc4f0 | 525 | commit. You can use `git add` (possibly interactively) or |
0b444cdb | 526 | 'git gui' (or both) to do that. |
f0fd889d JS |
527 | |
528 | - Commit the now-current index with whatever commit message is appropriate | |
529 | now. | |
530 | ||
531 | - Repeat the last two steps until your working tree is clean. | |
532 | ||
483bc4f0 | 533 | - Continue the rebase with `git rebase --continue`. |
f0fd889d JS |
534 | |
535 | If you are not absolutely sure that the intermediate revisions are | |
536 | consistent (they compile, pass the testsuite, etc.) you should use | |
0b444cdb | 537 | 'git stash' to stash away the not-yet-committed changes |
f0fd889d JS |
538 | after each commit, test, and amend the commit if fixes are necessary. |
539 | ||
540 | ||
90d1c08e TR |
541 | RECOVERING FROM UPSTREAM REBASE |
542 | ------------------------------- | |
543 | ||
544 | Rebasing (or any other form of rewriting) a branch that others have | |
545 | based work on is a bad idea: anyone downstream of it is forced to | |
546 | manually fix their history. This section explains how to do the fix | |
547 | from the downstream's point of view. The real fix, however, would be | |
548 | to avoid rebasing the upstream in the first place. | |
549 | ||
550 | To illustrate, suppose you are in a situation where someone develops a | |
551 | 'subsystem' branch, and you are working on a 'topic' that is dependent | |
552 | on this 'subsystem'. You might end up with a history like the | |
553 | following: | |
554 | ||
555 | ------------ | |
556 | o---o---o---o---o---o---o---o---o master | |
557 | \ | |
558 | o---o---o---o---o subsystem | |
559 | \ | |
560 | *---*---* topic | |
561 | ------------ | |
562 | ||
563 | If 'subsystem' is rebased against 'master', the following happens: | |
564 | ||
565 | ------------ | |
566 | o---o---o---o---o---o---o---o master | |
567 | \ \ | |
568 | o---o---o---o---o o'--o'--o'--o'--o' subsystem | |
569 | \ | |
570 | *---*---* topic | |
571 | ------------ | |
572 | ||
573 | If you now continue development as usual, and eventually merge 'topic' | |
574 | to 'subsystem', the commits from 'subsystem' will remain duplicated forever: | |
575 | ||
576 | ------------ | |
577 | o---o---o---o---o---o---o---o master | |
578 | \ \ | |
579 | o---o---o---o---o o'--o'--o'--o'--o'--M subsystem | |
580 | \ / | |
581 | *---*---*-..........-*--* topic | |
582 | ------------ | |
583 | ||
584 | Such duplicates are generally frowned upon because they clutter up | |
585 | history, making it harder to follow. To clean things up, you need to | |
586 | transplant the commits on 'topic' to the new 'subsystem' tip, i.e., | |
587 | rebase 'topic'. This becomes a ripple effect: anyone downstream from | |
588 | 'topic' is forced to rebase too, and so on! | |
589 | ||
590 | There are two kinds of fixes, discussed in the following subsections: | |
591 | ||
592 | Easy case: The changes are literally the same.:: | |
593 | ||
594 | This happens if the 'subsystem' rebase was a simple rebase and | |
595 | had no conflicts. | |
596 | ||
597 | Hard case: The changes are not the same.:: | |
598 | ||
599 | This happens if the 'subsystem' rebase had conflicts, or used | |
0205e72f MH |
600 | `\--interactive` to omit, edit, squash, or fixup commits; or |
601 | if the upstream used one of `commit \--amend`, `reset`, or | |
90d1c08e TR |
602 | `filter-branch`. |
603 | ||
604 | ||
605 | The easy case | |
606 | ~~~~~~~~~~~~~ | |
607 | ||
608 | Only works if the changes (patch IDs based on the diff contents) on | |
609 | 'subsystem' are literally the same before and after the rebase | |
610 | 'subsystem' did. | |
611 | ||
0b444cdb | 612 | In that case, the fix is easy because 'git rebase' knows to skip |
90d1c08e TR |
613 | changes that are already present in the new upstream. So if you say |
614 | (assuming you're on 'topic') | |
615 | ------------ | |
616 | $ git rebase subsystem | |
617 | ------------ | |
618 | you will end up with the fixed history | |
619 | ------------ | |
620 | o---o---o---o---o---o---o---o master | |
621 | \ | |
622 | o'--o'--o'--o'--o' subsystem | |
623 | \ | |
624 | *---*---* topic | |
625 | ------------ | |
626 | ||
627 | ||
628 | The hard case | |
629 | ~~~~~~~~~~~~~ | |
630 | ||
631 | Things get more complicated if the 'subsystem' changes do not exactly | |
632 | correspond to the ones before the rebase. | |
633 | ||
634 | NOTE: While an "easy case recovery" sometimes appears to be successful | |
635 | even in the hard case, it may have unintended consequences. For | |
636 | example, a commit that was removed via `git rebase | |
637 | \--interactive` will be **resurrected**! | |
638 | ||
0b444cdb | 639 | The idea is to manually tell 'git rebase' "where the old 'subsystem' |
90d1c08e TR |
640 | ended and your 'topic' began", that is, what the old merge-base |
641 | between them was. You will have to find a way to name the last commit | |
642 | of the old 'subsystem', for example: | |
643 | ||
0b444cdb | 644 | * With the 'subsystem' reflog: after 'git fetch', the old tip of |
90d1c08e TR |
645 | 'subsystem' is at `subsystem@\{1}`. Subsequent fetches will |
646 | increase the number. (See linkgit:git-reflog[1].) | |
647 | ||
648 | * Relative to the tip of 'topic': knowing that your 'topic' has three | |
649 | commits, the old tip of 'subsystem' must be `topic~3`. | |
650 | ||
651 | You can then transplant the old `subsystem..topic` to the new tip by | |
652 | saying (for the reflog case, and assuming you are on 'topic' already): | |
653 | ------------ | |
654 | $ git rebase --onto subsystem subsystem@{1} | |
655 | ------------ | |
656 | ||
657 | The ripple effect of a "hard case" recovery is especially bad: | |
658 | 'everyone' downstream from 'topic' will now have to perform a "hard | |
659 | case" recovery too! | |
660 | ||
661 | ||
cddb42d2 JN |
662 | BUGS |
663 | ---- | |
664 | The todo list presented by `--preserve-merges --interactive` does not | |
665 | represent the topology of the revision graph. Editing commits and | |
666 | rewording their commit messages should work fine, but attempts to | |
667 | reorder commits tend to produce counterintuitive results. | |
668 | ||
669 | For example, an attempt to rearrange | |
670 | ------------ | |
671 | 1 --- 2 --- 3 --- 4 --- 5 | |
672 | ------------ | |
673 | to | |
674 | ------------ | |
675 | 1 --- 2 --- 4 --- 3 --- 5 | |
676 | ------------ | |
677 | by moving the "pick 4" line will result in the following history: | |
678 | ------------ | |
679 | 3 | |
680 | / | |
681 | 1 --- 2 --- 4 --- 5 | |
682 | ------------ | |
683 | ||
1b1dce4b | 684 | Authors |
7fc9d69f | 685 | ------ |
59eb68aa | 686 | Written by Junio C Hamano <gitster@pobox.com> and |
1b1dce4b | 687 | Johannes E. Schindelin <johannes.schindelin@gmx.de> |
7fc9d69f JH |
688 | |
689 | Documentation | |
690 | -------------- | |
691 | Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>. | |
692 | ||
693 | GIT | |
694 | --- | |
9e1f0a85 | 695 | Part of the linkgit:git[1] suite |