Documentation / git-rebase.txton commit Fix typos / spelling in comments (3ea3c21)
   1git-rebase(1)
   2=============
   3
   4NAME
   5----
   6git-rebase - Forward-port local commits to the updated upstream head
   7
   8SYNOPSIS
   9--------
  10[verse]
  11'git rebase' [-i | --interactive] [options] [--onto <newbase>]
  12        <upstream> [<branch>]
  13'git rebase' [-i | --interactive] [options] --onto <newbase>
  14        --root [<branch>]
  15
  16'git rebase' --continue | --skip | --abort
  17
  18DESCRIPTION
  19-----------
  20If <branch> is specified, 'git-rebase' will perform an automatic
  21`git checkout <branch>` before doing anything else.  Otherwise
  22it remains on the current branch.
  23
  24All changes made by commits in the current branch but that are not
  25in <upstream> are saved to a temporary area.  This is the same set
  26of commits that would be shown by `git log <upstream>..HEAD` (or
  27`git log HEAD`, if --root is specified).
  28
  29The current branch is reset to <upstream>, or <newbase> if the
  30--onto option was supplied.  This has the exact same effect as
  31`git reset --hard <upstream>` (or <newbase>).  ORIG_HEAD is set
  32to point at the tip of the branch before the reset.
  33
  34The commits that were previously saved into the temporary area are
  35then reapplied to the current branch, one by one, in order. Note that
  36any commits in HEAD which introduce the same textual changes as a commit
  37in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream
  38with a different commit message or timestamp will be skipped).
  39
  40It is possible that a merge failure will prevent this process from being
  41completely automatic.  You will have to resolve any such merge failure
  42and run `git rebase --continue`.  Another option is to bypass the commit
  43that caused the merge failure with `git rebase --skip`.  To restore the
  44original <branch> and remove the .git/rebase-apply working files, use the
  45command `git rebase --abort` instead.
  46
  47Assume the following history exists and the current branch is "topic":
  48
  49------------
  50          A---B---C topic
  51         /
  52    D---E---F---G master
  53------------
  54
  55From this point, the result of either of the following commands:
  56
  57
  58    git rebase master
  59    git rebase master topic
  60
  61would be:
  62
  63------------
  64                  A'--B'--C' topic
  65                 /
  66    D---E---F---G master
  67------------
  68
  69The latter form is just a short-hand of `git checkout topic`
  70followed by `git rebase master`.
  71
  72If the upstream branch already contains a change you have made (e.g.,
  73because you mailed a patch which was applied upstream), then that commit
  74will be skipped. For example, running `git rebase master` on the
  75following history (in which A' and A introduce the same set of changes,
  76but have different committer information):
  77
  78------------
  79          A---B---C topic
  80         /
  81    D---E---A'---F master
  82------------
  83
  84will result in:
  85
  86------------
  87                   B'---C' topic
  88                  /
  89    D---E---A'---F master
  90------------
  91
  92Here is how you would transplant a topic branch based on one
  93branch to another, to pretend that you forked the topic branch
  94from the latter branch, using `rebase --onto`.
  95
  96First let's assume your 'topic' is based on branch 'next'.
  97For example, a feature developed in 'topic' depends on some
  98functionality which is found in 'next'.
  99
 100------------
 101    o---o---o---o---o  master
 102         \
 103          o---o---o---o---o  next
 104                           \
 105                            o---o---o  topic
 106------------
 107
 108We want to make 'topic' forked from branch 'master'; for example,
 109because the functionality on which 'topic' depends was merged into the
 110more stable 'master' branch. We want our tree to look like this:
 111
 112------------
 113    o---o---o---o---o  master
 114        |            \
 115        |             o'--o'--o'  topic
 116         \
 117          o---o---o---o---o  next
 118------------
 119
 120We can get this using the following command:
 121
 122    git rebase --onto master next topic
 123
 124
 125Another example of --onto option is to rebase part of a
 126branch.  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
 136then the command
 137
 138    git rebase --onto master topicA topicB
 139
 140would result in:
 141
 142------------
 143                 H'--I'--J'  topicB
 144                /
 145                | E---F---G  topicA
 146                |/
 147    A---B---C---D  master
 148------------
 149
 150This is useful when topicB does not depend on topicA.
 151
 152A range of commits could also be removed with rebase.  If we have
 153the following situation:
 154
 155------------
 156    E---F---G---H---I---J  topicA
 157------------
 158
 159then the command
 160
 161    git rebase --onto topicA~5 topicA~3 topicA
 162
 163would result in the removal of commits F and G:
 164
 165------------
 166    E---H'---I'---J'  topicA
 167------------
 168
 169This is useful if F and G were flawed in some way, or should not be
 170part of topicA.  Note that the argument to --onto and the <upstream>
 171parameter can be any valid commit-ish.
 172
 173In case of conflict, 'git-rebase' will stop at the first problematic commit
 174and leave conflict markers in the tree.  You can use 'git-diff' to locate
 175the markers (<<<<<<) and make edits to resolve the conflict.  For each
 176file you edit, you need to tell git that the conflict has been resolved,
 177typically this would be done with
 178
 179
 180    git add <filename>
 181
 182
 183After resolving the conflict manually and updating the index with the
 184desired resolution, you can continue the rebasing process with
 185
 186
 187    git rebase --continue
 188
 189
 190Alternatively, you can undo the 'git-rebase' with
 191
 192
 193    git rebase --abort
 194
 195CONFIGURATION
 196-------------
 197
 198rebase.stat::
 199        Whether to show a diffstat of what changed upstream since the last
 200        rebase. False by default.
 201
 202OPTIONS
 203-------
 204<newbase>::
 205        Starting point at which to create the new commits. If the
 206        --onto option is not specified, the starting point is
 207        <upstream>.  May be any valid commit, and not just an
 208        existing branch name.
 209
 210<upstream>::
 211        Upstream branch to compare against.  May be any valid commit,
 212        not just an existing branch name.
 213
 214<branch>::
 215        Working branch; defaults to HEAD.
 216
 217--continue::
 218        Restart the rebasing process after having resolved a merge conflict.
 219
 220--abort::
 221        Restore the original branch and abort the rebase operation.
 222
 223--skip::
 224        Restart the rebasing process by skipping the current patch.
 225
 226-m::
 227--merge::
 228        Use merging strategies to rebase.  When the recursive (default) merge
 229        strategy is used, this allows rebase to be aware of renames on the
 230        upstream side.
 231
 232-s <strategy>::
 233--strategy=<strategy>::
 234        Use the given merge strategy; can be supplied more than
 235        once to specify them in the order they should be tried.
 236        If there is no `-s` option, a built-in list of strategies
 237        is used instead ('git-merge-recursive' when merging a single
 238        head, 'git-merge-octopus' otherwise).  This implies --merge.
 239
 240-v::
 241--verbose::
 242        Be verbose. Implies --stat.
 243
 244--stat::
 245        Show a diffstat of what changed upstream since the last rebase. The
 246        diffstat is also controlled by the configuration option rebase.stat.
 247
 248-n::
 249--no-stat::
 250        Do not show a diffstat as part of the rebase process.
 251
 252--no-verify::
 253        This option bypasses the pre-rebase hook.  See also linkgit:githooks[5].
 254
 255-C<n>::
 256        Ensure at least <n> lines of surrounding context match before
 257        and after each change.  When fewer lines of surrounding
 258        context exist they all must match.  By default no context is
 259        ever ignored.
 260
 261-f::
 262--force-rebase::
 263        Force the rebase even if the current branch is a descendant
 264        of the commit you are rebasing onto.  Normally the command will
 265        exit with the message "Current branch is up to date" in such a
 266        situation.
 267
 268--whitespace=<option>::
 269        This flag is passed to the 'git-apply' program
 270        (see linkgit:git-apply[1]) that applies the patch.
 271        Incompatible with the --interactive option.
 272
 273--committer-date-is-author-date::
 274--ignore-date::
 275        These flags are passed to 'git-am' to easily change the dates
 276        of the rebased commits (see linkgit:git-am[1]).
 277
 278-i::
 279--interactive::
 280        Make a list of the commits which are about to be rebased.  Let the
 281        user edit that list before rebasing.  This mode can also be used to
 282        split commits (see SPLITTING COMMITS below).
 283
 284-p::
 285--preserve-merges::
 286        Instead of ignoring merges, try to recreate them.
 287
 288--root::
 289        Rebase all commits reachable from <branch>, instead of
 290        limiting them with an <upstream>.  This allows you to rebase
 291        the root commit(s) on a branch.  Must be used with --onto, and
 292        will skip changes already contained in <newbase> (instead of
 293        <upstream>).  When used together with --preserve-merges, 'all'
 294        root commits will be rewritten to have <newbase> as parent
 295        instead.
 296
 297include::merge-strategies.txt[]
 298
 299NOTES
 300-----
 301
 302You should understand the implications of using 'git-rebase' on a
 303repository that you share.  See also RECOVERING FROM UPSTREAM REBASE
 304below.
 305
 306When the git-rebase command is run, it will first execute a "pre-rebase"
 307hook if one exists.  You can use this hook to do sanity checks and
 308reject the rebase if it isn't appropriate.  Please see the template
 309pre-rebase hook script for an example.
 310
 311Upon completion, <branch> will be the current branch.
 312
 313INTERACTIVE MODE
 314----------------
 315
 316Rebasing interactively means that you have a chance to edit the commits
 317which are rebased.  You can reorder the commits, and you can
 318remove them (weeding out bad or otherwise unwanted patches).
 319
 320The interactive mode is meant for this type of workflow:
 321
 3221. have a wonderful idea
 3232. hack on the code
 3243. prepare a series for submission
 3254. submit
 326
 327where point 2. consists of several instances of
 328
 329a. regular use
 330 1. finish something worthy of a commit
 331 2. commit
 332b. independent fixup
 333 1. realize that something does not work
 334 2. fix that
 335 3. commit it
 336
 337Sometimes the thing fixed in b.2. cannot be amended to the not-quite
 338perfect commit it fixes, because that commit is buried deeply in a
 339patch series.  That is exactly what interactive rebase is for: use it
 340after plenty of "a"s and "b"s, by rearranging and editing
 341commits, and squashing multiple commits into one.
 342
 343Start it with the last commit you want to retain as-is:
 344
 345        git rebase -i <after-this-commit>
 346
 347An editor will be fired up with all the commits in your current branch
 348(ignoring merge commits), which come after the given commit.  You can
 349reorder the commits in this list to your heart's content, and you can
 350remove them.  The list looks more or less like this:
 351
 352-------------------------------------------
 353pick deadbee The oneline of this commit
 354pick fa1afe1 The oneline of the next commit
 355...
 356-------------------------------------------
 357
 358The oneline descriptions are purely for your pleasure; 'git-rebase' will
 359not look at them but at the commit names ("deadbee" and "fa1afe1" in this
 360example), so do not delete or edit the names.
 361
 362By replacing the command "pick" with the command "edit", you can tell
 363'git-rebase' to stop after applying that commit, so that you can edit
 364the files and/or the commit message, amend the commit, and continue
 365rebasing.
 366
 367If you want to fold two or more commits into one, replace the command
 368"pick" with "squash" for the second and subsequent commit.  If the
 369commits had different authors, it will attribute the squashed commit to
 370the author of the first commit.
 371
 372In both cases, or when a "pick" does not succeed (because of merge
 373errors), the loop will stop to let you fix things, and you can continue
 374the loop with `git rebase --continue`.
 375
 376For example, if you want to reorder the last 5 commits, such that what
 377was HEAD~4 becomes the new HEAD. To achieve that, you would call
 378'git-rebase' like this:
 379
 380----------------------
 381$ git rebase -i HEAD~5
 382----------------------
 383
 384And move the first patch to the end of the list.
 385
 386You might want to preserve merges, if you have a history like this:
 387
 388------------------
 389           X
 390            \
 391         A---M---B
 392        /
 393---o---O---P---Q
 394------------------
 395
 396Suppose you want to rebase the side branch starting at "A" to "Q". Make
 397sure that the current HEAD is "B", and call
 398
 399-----------------------------
 400$ git rebase -i -p --onto Q O
 401-----------------------------
 402
 403
 404SPLITTING COMMITS
 405-----------------
 406
 407In interactive mode, you can mark commits with the action "edit".  However,
 408this does not necessarily mean that 'git-rebase' expects the result of this
 409edit to be exactly one commit.  Indeed, you can undo the commit, or you can
 410add other commits.  This can be used to split a commit into two:
 411
 412- Start an interactive rebase with `git rebase -i <commit>^`, where
 413  <commit> is the commit you want to split.  In fact, any commit range
 414  will do, as long as it contains that commit.
 415
 416- Mark the commit you want to split with the action "edit".
 417
 418- When it comes to editing that commit, execute `git reset HEAD^`.  The
 419  effect is that the HEAD is rewound by one, and the index follows suit.
 420  However, the working tree stays the same.
 421
 422- Now add the changes to the index that you want to have in the first
 423  commit.  You can use `git add` (possibly interactively) or
 424  'git-gui' (or both) to do that.
 425
 426- Commit the now-current index with whatever commit message is appropriate
 427  now.
 428
 429- Repeat the last two steps until your working tree is clean.
 430
 431- Continue the rebase with `git rebase --continue`.
 432
 433If you are not absolutely sure that the intermediate revisions are
 434consistent (they compile, pass the testsuite, etc.) you should use
 435'git-stash' to stash away the not-yet-committed changes
 436after each commit, test, and amend the commit if fixes are necessary.
 437
 438
 439RECOVERING FROM UPSTREAM REBASE
 440-------------------------------
 441
 442Rebasing (or any other form of rewriting) a branch that others have
 443based work on is a bad idea: anyone downstream of it is forced to
 444manually fix their history.  This section explains how to do the fix
 445from the downstream's point of view.  The real fix, however, would be
 446to avoid rebasing the upstream in the first place.
 447
 448To illustrate, suppose you are in a situation where someone develops a
 449'subsystem' branch, and you are working on a 'topic' that is dependent
 450on this 'subsystem'.  You might end up with a history like the
 451following:
 452
 453------------
 454    o---o---o---o---o---o---o---o---o  master
 455         \
 456          o---o---o---o---o  subsystem
 457                           \
 458                            *---*---*  topic
 459------------
 460
 461If 'subsystem' is rebased against 'master', the following happens:
 462
 463------------
 464    o---o---o---o---o---o---o---o  master
 465         \                       \
 466          o---o---o---o---o       o'--o'--o'--o'--o'  subsystem
 467                           \
 468                            *---*---*  topic
 469------------
 470
 471If you now continue development as usual, and eventually merge 'topic'
 472to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
 473
 474------------
 475    o---o---o---o---o---o---o---o  master
 476         \                       \
 477          o---o---o---o---o       o'--o'--o'--o'--o'--M  subsystem
 478                           \                         /
 479                            *---*---*-..........-*--*  topic
 480------------
 481
 482Such duplicates are generally frowned upon because they clutter up
 483history, making it harder to follow.  To clean things up, you need to
 484transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
 485rebase 'topic'.  This becomes a ripple effect: anyone downstream from
 486'topic' is forced to rebase too, and so on!
 487
 488There are two kinds of fixes, discussed in the following subsections:
 489
 490Easy case: The changes are literally the same.::
 491
 492        This happens if the 'subsystem' rebase was a simple rebase and
 493        had no conflicts.
 494
 495Hard case: The changes are not the same.::
 496
 497        This happens if the 'subsystem' rebase had conflicts, or used
 498        `\--interactive` to omit, edit, or squash commits; or if the
 499        upstream used one of `commit \--amend`, `reset`, or
 500        `filter-branch`.
 501
 502
 503The easy case
 504~~~~~~~~~~~~~
 505
 506Only works if the changes (patch IDs based on the diff contents) on
 507'subsystem' are literally the same before and after the rebase
 508'subsystem' did.
 509
 510In that case, the fix is easy because 'git-rebase' knows to skip
 511changes that are already present in the new upstream.  So if you say
 512(assuming you're on 'topic')
 513------------
 514    $ git rebase subsystem
 515------------
 516you will end up with the fixed history
 517------------
 518    o---o---o---o---o---o---o---o  master
 519                                 \
 520                                  o'--o'--o'--o'--o'  subsystem
 521                                                   \
 522                                                    *---*---*  topic
 523------------
 524
 525
 526The hard case
 527~~~~~~~~~~~~~
 528
 529Things get more complicated if the 'subsystem' changes do not exactly
 530correspond to the ones before the rebase.
 531
 532NOTE: While an "easy case recovery" sometimes appears to be successful
 533      even in the hard case, it may have unintended consequences.  For
 534      example, a commit that was removed via `git rebase
 535      \--interactive` will be **resurrected**!
 536
 537The idea is to manually tell 'git-rebase' "where the old 'subsystem'
 538ended and your 'topic' began", that is, what the old merge-base
 539between them was.  You will have to find a way to name the last commit
 540of the old 'subsystem', for example:
 541
 542* With the 'subsystem' reflog: after 'git-fetch', the old tip of
 543  'subsystem' is at `subsystem@\{1}`.  Subsequent fetches will
 544  increase the number.  (See linkgit:git-reflog[1].)
 545
 546* Relative to the tip of 'topic': knowing that your 'topic' has three
 547  commits, the old tip of 'subsystem' must be `topic~3`.
 548
 549You can then transplant the old `subsystem..topic` to the new tip by
 550saying (for the reflog case, and assuming you are on 'topic' already):
 551------------
 552    $ git rebase --onto subsystem subsystem@{1}
 553------------
 554
 555The ripple effect of a "hard case" recovery is especially bad:
 556'everyone' downstream from 'topic' will now have to perform a "hard
 557case" recovery too!
 558
 559
 560Authors
 561------
 562Written by Junio C Hamano <gitster@pobox.com> and
 563Johannes E. Schindelin <johannes.schindelin@gmx.de>
 564
 565Documentation
 566--------------
 567Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
 568
 569GIT
 570---
 571Part of the linkgit:git[1] suite