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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 | |
ee55703b DN |
69 | *NOTE:* The latter form is just a short-hand of `git checkout topic` |
70 | followed by `git rebase master`. When rebase exits `topic` will | |
71 | remain the checked-out branch. | |
69a60af5 | 72 | |
ff905462 JK |
73 | If the upstream branch already contains a change you have made (e.g., |
74 | because you mailed a patch which was applied upstream), then that commit | |
b1889c36 | 75 | will be skipped. For example, running `git rebase master` on the |
ff905462 JK |
76 | following history (in which A' and A introduce the same set of changes, |
77 | but have different committer information): | |
78 | ||
79 | ------------ | |
80 | A---B---C topic | |
81 | / | |
82 | D---E---A'---F master | |
83 | ------------ | |
84 | ||
85 | will result in: | |
86 | ||
87 | ------------ | |
88 | B'---C' topic | |
89 | / | |
90 | D---E---A'---F master | |
91 | ------------ | |
92 | ||
e52775f4 JN |
93 | Here is how you would transplant a topic branch based on one |
94 | branch to another, to pretend that you forked the topic branch | |
95 | from the latter branch, using `rebase --onto`. | |
69a60af5 | 96 | |
e52775f4 | 97 | First let's assume your 'topic' is based on branch 'next'. |
e2b850b2 | 98 | For example, a feature developed in 'topic' depends on some |
e52775f4 | 99 | functionality which is found in 'next'. |
69a60af5 | 100 | |
031321c6 | 101 | ------------ |
e52775f4 JN |
102 | o---o---o---o---o master |
103 | \ | |
104 | o---o---o---o---o next | |
105 | \ | |
106 | o---o---o topic | |
107 | ------------ | |
108 | ||
e2b850b2 GD |
109 | We want to make 'topic' forked from branch 'master'; for example, |
110 | because the functionality on which 'topic' depends was merged into the | |
111 | more stable 'master' branch. We want our tree to look like this: | |
e52775f4 JN |
112 | |
113 | ------------ | |
114 | o---o---o---o---o master | |
115 | | \ | |
116 | | o'--o'--o' topic | |
117 | \ | |
118 | o---o---o---o---o next | |
031321c6 | 119 | ------------ |
7fc9d69f | 120 | |
e52775f4 JN |
121 | We can get this using the following command: |
122 | ||
b1889c36 | 123 | git rebase --onto master next topic |
e52775f4 JN |
124 | |
125 | ||
126 | Another example of --onto option is to rebase part of a | |
127 | branch. If we have the following situation: | |
128 | ||
129 | ------------ | |
130 | H---I---J topicB | |
131 | / | |
132 | E---F---G topicA | |
133 | / | |
134 | A---B---C---D master | |
135 | ------------ | |
136 | ||
137 | then the command | |
138 | ||
b1889c36 | 139 | git rebase --onto master topicA topicB |
e52775f4 JN |
140 | |
141 | would result in: | |
142 | ||
143 | ------------ | |
144 | H'--I'--J' topicB | |
145 | / | |
146 | | E---F---G topicA | |
147 | |/ | |
148 | A---B---C---D master | |
149 | ------------ | |
150 | ||
151 | This is useful when topicB does not depend on topicA. | |
152 | ||
ea81fcc5 SP |
153 | A range of commits could also be removed with rebase. If we have |
154 | the following situation: | |
155 | ||
156 | ------------ | |
157 | E---F---G---H---I---J topicA | |
158 | ------------ | |
159 | ||
160 | then the command | |
161 | ||
b1889c36 | 162 | git rebase --onto topicA~5 topicA~3 topicA |
ea81fcc5 SP |
163 | |
164 | would result in the removal of commits F and G: | |
165 | ||
166 | ------------ | |
167 | E---H'---I'---J' topicA | |
168 | ------------ | |
169 | ||
170 | This is useful if F and G were flawed in some way, or should not be | |
171 | part of topicA. Note that the argument to --onto and the <upstream> | |
172 | parameter can be any valid commit-ish. | |
173 | ||
0b444cdb TR |
174 | In case of conflict, 'git rebase' will stop at the first problematic commit |
175 | and leave conflict markers in the tree. You can use 'git diff' to locate | |
031321c6 SE |
176 | the markers (<<<<<<) and make edits to resolve the conflict. For each |
177 | file you edit, you need to tell git that the conflict has been resolved, | |
178 | typically this would be done with | |
179 | ||
180 | ||
d7f078b8 | 181 | git add <filename> |
031321c6 SE |
182 | |
183 | ||
184 | After resolving the conflict manually and updating the index with the | |
185 | desired resolution, you can continue the rebasing process with | |
186 | ||
187 | ||
188 | git rebase --continue | |
8978d043 | 189 | |
8978d043 | 190 | |
0b444cdb | 191 | Alternatively, you can undo the 'git rebase' with |
8978d043 | 192 | |
031321c6 SE |
193 | |
194 | git rebase --abort | |
8978d043 | 195 | |
a9c3821c TAV |
196 | CONFIGURATION |
197 | ------------- | |
198 | ||
199 | rebase.stat:: | |
200 | Whether to show a diffstat of what changed upstream since the last | |
201 | rebase. False by default. | |
202 | ||
dd1e5b31 HV |
203 | rebase.autosquash:: |
204 | If set to true enable '--autosquash' option by default. | |
205 | ||
7fc9d69f JH |
206 | OPTIONS |
207 | ------- | |
69a60af5 CW |
208 | <newbase>:: |
209 | Starting point at which to create the new commits. If the | |
210 | --onto option is not specified, the starting point is | |
ea81fcc5 SP |
211 | <upstream>. May be any valid commit, and not just an |
212 | existing branch name. | |
873c3472 | 213 | + |
b9190e79 | 214 | As a special case, you may use "A\...B" as a shortcut for the |
873c3472 MG |
215 | merge base of A and B if there is exactly one merge base. You can |
216 | leave out at most one of A and B, in which case it defaults to HEAD. | |
69a60af5 | 217 | |
52a22d1e | 218 | <upstream>:: |
ea81fcc5 SP |
219 | Upstream branch to compare against. May be any valid commit, |
220 | not just an existing branch name. | |
7fc9d69f | 221 | |
228382ae | 222 | <branch>:: |
52a22d1e | 223 | Working branch; defaults to HEAD. |
7fc9d69f | 224 | |
031321c6 SE |
225 | --continue:: |
226 | Restart the rebasing process after having resolved a merge conflict. | |
227 | ||
228 | --abort:: | |
229 | Restore the original branch and abort the rebase operation. | |
230 | ||
58634dbf EW |
231 | --skip:: |
232 | Restart the rebasing process by skipping the current patch. | |
58634dbf | 233 | |
3240240f SB |
234 | -m:: |
235 | --merge:: | |
58634dbf EW |
236 | Use merging strategies to rebase. When the recursive (default) merge |
237 | strategy is used, this allows rebase to be aware of renames on the | |
238 | upstream side. | |
31ddd1ee TR |
239 | + |
240 | Note that a rebase merge works by replaying each commit from the working | |
241 | branch on top of the <upstream> branch. Because of this, when a merge | |
242 | conflict happens, the side reported as 'ours' is the so-far rebased | |
243 | series, starting with <upstream>, and 'theirs' is the working branch. In | |
244 | other words, the sides are swapped. | |
58634dbf | 245 | |
3240240f SB |
246 | -s <strategy>:: |
247 | --strategy=<strategy>:: | |
06f39190 | 248 | Use the given merge strategy. |
0b444cdb | 249 | If there is no `-s` option 'git merge-recursive' is used |
31ddd1ee TR |
250 | instead. This implies --merge. |
251 | + | |
0b444cdb | 252 | Because 'git rebase' replays each commit from the working branch |
31ddd1ee TR |
253 | on top of the <upstream> branch using the given strategy, using |
254 | the 'ours' strategy simply discards all patches from the <branch>, | |
255 | which makes little sense. | |
58634dbf | 256 | |
93ce190c ML |
257 | -X <strategy-option>:: |
258 | --strategy-option=<strategy-option>:: | |
259 | Pass the <strategy-option> through to the merge strategy. | |
260 | This implies `\--merge` and, if no strategy has been | |
261 | specified, `-s recursive`. Note the reversal of 'ours' and | |
262 | 'theirs' as noted in above for the `-m` option. | |
263 | ||
0e987a12 SB |
264 | -q:: |
265 | --quiet:: | |
266 | Be quiet. Implies --no-stat. | |
267 | ||
3240240f SB |
268 | -v:: |
269 | --verbose:: | |
a9c3821c TAV |
270 | Be verbose. Implies --stat. |
271 | ||
272 | --stat:: | |
273 | Show a diffstat of what changed upstream since the last rebase. The | |
274 | diffstat is also controlled by the configuration option rebase.stat. | |
275 | ||
276 | -n:: | |
277 | --no-stat:: | |
278 | Do not show a diffstat as part of the rebase process. | |
b758789c | 279 | |
fd631d58 NS |
280 | --no-verify:: |
281 | This option bypasses the pre-rebase hook. See also linkgit:githooks[5]. | |
282 | ||
7baf9c4b MZ |
283 | --verify:: |
284 | Allows the pre-rebase hook to run, which is the default. This option can | |
285 | be used to override --no-verify. See also linkgit:githooks[5]. | |
286 | ||
67dad687 MT |
287 | -C<n>:: |
288 | Ensure at least <n> lines of surrounding context match before | |
289 | and after each change. When fewer lines of surrounding | |
290 | context exist they all must match. By default no context is | |
291 | ever ignored. | |
292 | ||
5e75d56f MB |
293 | -f:: |
294 | --force-rebase:: | |
295 | Force the rebase even if the current branch is a descendant | |
b4995494 | 296 | of the commit you are rebasing onto. Normally non-interactive rebase will |
5e75d56f MB |
297 | exit with the message "Current branch is up to date" in such a |
298 | situation. | |
b4995494 MB |
299 | Incompatible with the --interactive option. |
300 | + | |
301 | You may find this (or --no-ff with an interactive rebase) helpful after | |
302 | reverting a topic branch merge, as this option recreates the topic branch with | |
303 | fresh commits so it can be remerged successfully without needing to "revert | |
304 | the reversion" (see the | |
305 | link:howto/revert-a-faulty-merge.txt[revert-a-faulty-merge How-To] for details). | |
5e75d56f | 306 | |
86c91f91 | 307 | --ignore-whitespace:: |
749485f6 | 308 | --whitespace=<option>:: |
0b444cdb | 309 | These flag are passed to the 'git apply' program |
5162e697 | 310 | (see linkgit:git-apply[1]) that applies the patch. |
7fe54385 | 311 | Incompatible with the --interactive option. |
059f446d | 312 | |
570ccad3 MB |
313 | --committer-date-is-author-date:: |
314 | --ignore-date:: | |
0b444cdb | 315 | These flags are passed to 'git am' to easily change the dates |
570ccad3 | 316 | of the rebased commits (see linkgit:git-am[1]). |
56a05720 | 317 | Incompatible with the --interactive option. |
570ccad3 | 318 | |
3240240f SB |
319 | -i:: |
320 | --interactive:: | |
1b1dce4b | 321 | Make a list of the commits which are about to be rebased. Let the |
f0fd889d JS |
322 | user edit that list before rebasing. This mode can also be used to |
323 | split commits (see SPLITTING COMMITS below). | |
1b1dce4b | 324 | |
3240240f SB |
325 | -p:: |
326 | --preserve-merges:: | |
f8cca019 | 327 | Instead of ignoring merges, try to recreate them. |
cddb42d2 JN |
328 | + |
329 | This uses the `--interactive` machinery internally, but combining it | |
330 | with the `--interactive` option explicitly is generally not a good | |
331 | idea unless you know what you are doing (see BUGS below). | |
332 | ||
f09c9b8c | 333 | |
be496621 TR |
334 | --root:: |
335 | Rebase all commits reachable from <branch>, instead of | |
336 | limiting them with an <upstream>. This allows you to rebase | |
337 | the root commit(s) on a branch. Must be used with --onto, and | |
338 | will skip changes already contained in <newbase> (instead of | |
339 | <upstream>). When used together with --preserve-merges, 'all' | |
340 | root commits will be rewritten to have <newbase> as parent | |
341 | instead. | |
342 | ||
f59baa50 | 343 | --autosquash:: |
dd1e5b31 | 344 | --no-autosquash:: |
f59baa50 NS |
345 | When the commit log message begins with "squash! ..." (or |
346 | "fixup! ..."), and there is a commit whose title begins with | |
347 | the same ..., automatically modify the todo list of rebase -i | |
42cfcd20 | 348 | so that the commit marked for squashing comes right after the |
f59baa50 NS |
349 | commit to be modified, and change the action of the moved |
350 | commit from `pick` to `squash` (or `fixup`). | |
351 | + | |
b4995494 | 352 | This option is only valid when the '--interactive' option is used. |
dd1e5b31 HV |
353 | + |
354 | If the '--autosquash' option is enabled by default using the | |
355 | configuration variable `rebase.autosquash`, this option can be | |
356 | used to override and disable this setting. | |
b4995494 MB |
357 | |
358 | --no-ff:: | |
359 | With --interactive, cherry-pick all rebased commits instead of | |
360 | fast-forwarding over the unchanged ones. This ensures that the | |
361 | entire history of the rebased branch is composed of new commits. | |
362 | + | |
363 | Without --interactive, this is a synonym for --force-rebase. | |
364 | + | |
365 | You may find this helpful after reverting a topic branch merge, as this option | |
366 | recreates the topic branch with fresh commits so it can be remerged | |
367 | successfully without needing to "revert the reversion" (see the | |
368 | link:howto/revert-a-faulty-merge.txt[revert-a-faulty-merge How-To] for details). | |
f59baa50 | 369 | |
58634dbf EW |
370 | include::merge-strategies.txt[] |
371 | ||
031321c6 SE |
372 | NOTES |
373 | ----- | |
90d1c08e | 374 | |
0b444cdb | 375 | You should understand the implications of using 'git rebase' on a |
90d1c08e TR |
376 | repository that you share. See also RECOVERING FROM UPSTREAM REBASE |
377 | below. | |
031321c6 | 378 | |
467c0197 | 379 | When the git-rebase command is run, it will first execute a "pre-rebase" |
031321c6 SE |
380 | hook if one exists. You can use this hook to do sanity checks and |
381 | reject the rebase if it isn't appropriate. Please see the template | |
382 | pre-rebase hook script for an example. | |
383 | ||
702088af | 384 | Upon completion, <branch> will be the current branch. |
031321c6 | 385 | |
1b1dce4b JS |
386 | INTERACTIVE MODE |
387 | ---------------- | |
388 | ||
389 | Rebasing interactively means that you have a chance to edit the commits | |
390 | which are rebased. You can reorder the commits, and you can | |
391 | remove them (weeding out bad or otherwise unwanted patches). | |
392 | ||
393 | The interactive mode is meant for this type of workflow: | |
394 | ||
395 | 1. have a wonderful idea | |
396 | 2. hack on the code | |
397 | 3. prepare a series for submission | |
398 | 4. submit | |
399 | ||
400 | where point 2. consists of several instances of | |
401 | ||
402 | a. regular use | |
403 | 1. finish something worthy of a commit | |
404 | 2. commit | |
405 | b. independent fixup | |
406 | 1. realize that something does not work | |
407 | 2. fix that | |
408 | 3. commit it | |
409 | ||
410 | Sometimes the thing fixed in b.2. cannot be amended to the not-quite | |
411 | perfect commit it fixes, because that commit is buried deeply in a | |
412 | patch series. That is exactly what interactive rebase is for: use it | |
413 | after plenty of "a"s and "b"s, by rearranging and editing | |
414 | commits, and squashing multiple commits into one. | |
415 | ||
416 | Start it with the last commit you want to retain as-is: | |
417 | ||
418 | git rebase -i <after-this-commit> | |
419 | ||
420 | An editor will be fired up with all the commits in your current branch | |
421 | (ignoring merge commits), which come after the given commit. You can | |
422 | reorder the commits in this list to your heart's content, and you can | |
423 | remove them. The list looks more or less like this: | |
424 | ||
425 | ------------------------------------------- | |
426 | pick deadbee The oneline of this commit | |
427 | pick fa1afe1 The oneline of the next commit | |
428 | ... | |
429 | ------------------------------------------- | |
430 | ||
0b444cdb | 431 | The oneline descriptions are purely for your pleasure; 'git rebase' will |
1b1dce4b JS |
432 | not look at them but at the commit names ("deadbee" and "fa1afe1" in this |
433 | example), so do not delete or edit the names. | |
434 | ||
435 | By replacing the command "pick" with the command "edit", you can tell | |
0b444cdb | 436 | 'git rebase' to stop after applying that commit, so that you can edit |
1b1dce4b JS |
437 | the files and/or the commit message, amend the commit, and continue |
438 | rebasing. | |
439 | ||
6741aa6c BG |
440 | If you just want to edit the commit message for a commit, replace the |
441 | command "pick" with the command "reword". | |
442 | ||
1b1dce4b | 443 | If you want to fold two or more commits into one, replace the command |
0205e72f MH |
444 | "pick" for the second and subsequent commits with "squash" or "fixup". |
445 | If the commits had different authors, the folded commit will be | |
446 | attributed to the author of the first commit. The suggested commit | |
447 | message for the folded commit is the concatenation of the commit | |
448 | messages of the first commit and of those with the "squash" command, | |
449 | but omits the commit messages of commits with the "fixup" command. | |
1b1dce4b | 450 | |
0b444cdb | 451 | 'git rebase' will stop when "pick" has been replaced with "edit" or |
6741aa6c BG |
452 | when a command fails due to merge errors. When you are done editing |
453 | and/or resolving conflicts you can continue with `git rebase --continue`. | |
1b1dce4b JS |
454 | |
455 | For example, if you want to reorder the last 5 commits, such that what | |
456 | was HEAD~4 becomes the new HEAD. To achieve that, you would call | |
0b444cdb | 457 | 'git rebase' like this: |
1b1dce4b JS |
458 | |
459 | ---------------------- | |
460 | $ git rebase -i HEAD~5 | |
461 | ---------------------- | |
462 | ||
463 | And move the first patch to the end of the list. | |
464 | ||
f09c9b8c JS |
465 | You might want to preserve merges, if you have a history like this: |
466 | ||
467 | ------------------ | |
468 | X | |
469 | \ | |
470 | A---M---B | |
471 | / | |
472 | ---o---O---P---Q | |
473 | ------------------ | |
474 | ||
475 | Suppose you want to rebase the side branch starting at "A" to "Q". Make | |
476 | sure that the current HEAD is "B", and call | |
477 | ||
478 | ----------------------------- | |
479 | $ git rebase -i -p --onto Q O | |
480 | ----------------------------- | |
481 | ||
cd035b1c MM |
482 | Reordering and editing commits usually creates untested intermediate |
483 | steps. You may want to check that your history editing did not break | |
484 | anything by running a test, or at least recompiling at intermediate | |
485 | points in history by using the "exec" command (shortcut "x"). You may | |
486 | do so by creating a todo list like this one: | |
487 | ||
488 | ------------------------------------------- | |
489 | pick deadbee Implement feature XXX | |
490 | fixup f1a5c00 Fix to feature XXX | |
491 | exec make | |
492 | pick c0ffeee The oneline of the next commit | |
493 | edit deadbab The oneline of the commit after | |
494 | exec cd subdir; make test | |
495 | ... | |
496 | ------------------------------------------- | |
497 | ||
498 | The interactive rebase will stop when a command fails (i.e. exits with | |
499 | non-0 status) to give you an opportunity to fix the problem. You can | |
500 | continue with `git rebase --continue`. | |
501 | ||
502 | The "exec" command launches the command in a shell (the one specified | |
503 | in `$SHELL`, or the default shell if `$SHELL` is not set), so you can | |
504 | use shell features (like "cd", ">", ";" ...). The command is run from | |
505 | the root of the working tree. | |
f0fd889d JS |
506 | |
507 | SPLITTING COMMITS | |
508 | ----------------- | |
509 | ||
510 | In interactive mode, you can mark commits with the action "edit". However, | |
0b444cdb | 511 | this does not necessarily mean that 'git rebase' expects the result of this |
f0fd889d JS |
512 | edit to be exactly one commit. Indeed, you can undo the commit, or you can |
513 | add other commits. This can be used to split a commit into two: | |
514 | ||
483bc4f0 | 515 | - Start an interactive rebase with `git rebase -i <commit>^`, where |
f0fd889d JS |
516 | <commit> is the commit you want to split. In fact, any commit range |
517 | will do, as long as it contains that commit. | |
518 | ||
519 | - Mark the commit you want to split with the action "edit". | |
520 | ||
483bc4f0 | 521 | - When it comes to editing that commit, execute `git reset HEAD^`. The |
f0fd889d JS |
522 | effect is that the HEAD is rewound by one, and the index follows suit. |
523 | However, the working tree stays the same. | |
524 | ||
525 | - Now add the changes to the index that you want to have in the first | |
483bc4f0 | 526 | commit. You can use `git add` (possibly interactively) or |
0b444cdb | 527 | 'git gui' (or both) to do that. |
f0fd889d JS |
528 | |
529 | - Commit the now-current index with whatever commit message is appropriate | |
530 | now. | |
531 | ||
532 | - Repeat the last two steps until your working tree is clean. | |
533 | ||
483bc4f0 | 534 | - Continue the rebase with `git rebase --continue`. |
f0fd889d JS |
535 | |
536 | If you are not absolutely sure that the intermediate revisions are | |
537 | consistent (they compile, pass the testsuite, etc.) you should use | |
0b444cdb | 538 | 'git stash' to stash away the not-yet-committed changes |
f0fd889d JS |
539 | after each commit, test, and amend the commit if fixes are necessary. |
540 | ||
541 | ||
90d1c08e TR |
542 | RECOVERING FROM UPSTREAM REBASE |
543 | ------------------------------- | |
544 | ||
545 | Rebasing (or any other form of rewriting) a branch that others have | |
546 | based work on is a bad idea: anyone downstream of it is forced to | |
547 | manually fix their history. This section explains how to do the fix | |
548 | from the downstream's point of view. The real fix, however, would be | |
549 | to avoid rebasing the upstream in the first place. | |
550 | ||
551 | To illustrate, suppose you are in a situation where someone develops a | |
552 | 'subsystem' branch, and you are working on a 'topic' that is dependent | |
553 | on this 'subsystem'. You might end up with a history like the | |
554 | following: | |
555 | ||
556 | ------------ | |
557 | o---o---o---o---o---o---o---o---o master | |
558 | \ | |
559 | o---o---o---o---o subsystem | |
560 | \ | |
561 | *---*---* topic | |
562 | ------------ | |
563 | ||
564 | If 'subsystem' is rebased against 'master', the following happens: | |
565 | ||
566 | ------------ | |
567 | o---o---o---o---o---o---o---o master | |
568 | \ \ | |
569 | o---o---o---o---o o'--o'--o'--o'--o' subsystem | |
570 | \ | |
571 | *---*---* topic | |
572 | ------------ | |
573 | ||
574 | If you now continue development as usual, and eventually merge 'topic' | |
575 | to 'subsystem', the commits from 'subsystem' will remain duplicated forever: | |
576 | ||
577 | ------------ | |
578 | o---o---o---o---o---o---o---o master | |
579 | \ \ | |
580 | o---o---o---o---o o'--o'--o'--o'--o'--M subsystem | |
581 | \ / | |
582 | *---*---*-..........-*--* topic | |
583 | ------------ | |
584 | ||
585 | Such duplicates are generally frowned upon because they clutter up | |
586 | history, making it harder to follow. To clean things up, you need to | |
587 | transplant the commits on 'topic' to the new 'subsystem' tip, i.e., | |
588 | rebase 'topic'. This becomes a ripple effect: anyone downstream from | |
589 | 'topic' is forced to rebase too, and so on! | |
590 | ||
591 | There are two kinds of fixes, discussed in the following subsections: | |
592 | ||
593 | Easy case: The changes are literally the same.:: | |
594 | ||
595 | This happens if the 'subsystem' rebase was a simple rebase and | |
596 | had no conflicts. | |
597 | ||
598 | Hard case: The changes are not the same.:: | |
599 | ||
600 | This happens if the 'subsystem' rebase had conflicts, or used | |
0205e72f MH |
601 | `\--interactive` to omit, edit, squash, or fixup commits; or |
602 | if the upstream used one of `commit \--amend`, `reset`, or | |
90d1c08e TR |
603 | `filter-branch`. |
604 | ||
605 | ||
606 | The easy case | |
607 | ~~~~~~~~~~~~~ | |
608 | ||
609 | Only works if the changes (patch IDs based on the diff contents) on | |
610 | 'subsystem' are literally the same before and after the rebase | |
611 | 'subsystem' did. | |
612 | ||
0b444cdb | 613 | In that case, the fix is easy because 'git rebase' knows to skip |
90d1c08e TR |
614 | changes that are already present in the new upstream. So if you say |
615 | (assuming you're on 'topic') | |
616 | ------------ | |
617 | $ git rebase subsystem | |
618 | ------------ | |
619 | you will end up with the fixed history | |
620 | ------------ | |
621 | o---o---o---o---o---o---o---o master | |
622 | \ | |
623 | o'--o'--o'--o'--o' subsystem | |
624 | \ | |
625 | *---*---* topic | |
626 | ------------ | |
627 | ||
628 | ||
629 | The hard case | |
630 | ~~~~~~~~~~~~~ | |
631 | ||
632 | Things get more complicated if the 'subsystem' changes do not exactly | |
633 | correspond to the ones before the rebase. | |
634 | ||
635 | NOTE: While an "easy case recovery" sometimes appears to be successful | |
636 | even in the hard case, it may have unintended consequences. For | |
637 | example, a commit that was removed via `git rebase | |
638 | \--interactive` will be **resurrected**! | |
639 | ||
0b444cdb | 640 | The idea is to manually tell 'git rebase' "where the old 'subsystem' |
90d1c08e TR |
641 | ended and your 'topic' began", that is, what the old merge-base |
642 | between them was. You will have to find a way to name the last commit | |
643 | of the old 'subsystem', for example: | |
644 | ||
0b444cdb | 645 | * With the 'subsystem' reflog: after 'git fetch', the old tip of |
90d1c08e TR |
646 | 'subsystem' is at `subsystem@\{1}`. Subsequent fetches will |
647 | increase the number. (See linkgit:git-reflog[1].) | |
648 | ||
649 | * Relative to the tip of 'topic': knowing that your 'topic' has three | |
650 | commits, the old tip of 'subsystem' must be `topic~3`. | |
651 | ||
652 | You can then transplant the old `subsystem..topic` to the new tip by | |
653 | saying (for the reflog case, and assuming you are on 'topic' already): | |
654 | ------------ | |
655 | $ git rebase --onto subsystem subsystem@{1} | |
656 | ------------ | |
657 | ||
658 | The ripple effect of a "hard case" recovery is especially bad: | |
659 | 'everyone' downstream from 'topic' will now have to perform a "hard | |
660 | case" recovery too! | |
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 | ||
7fc9d69f JH |
684 | GIT |
685 | --- | |
9e1f0a85 | 686 | Part of the linkgit:git[1] suite |