Doc/checkout: checking out using @{-N} can lead to detached state
[git/git.git] / Documentation / git-checkout.txt
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1git-checkout(1)
2===============
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3
4NAME
5----
c4ac525c 6git-checkout - Switch branches or restore working tree files
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7
8SYNOPSIS
9--------
71bb1033 10[verse]
76cfadfc 11'git checkout' [-q] [-f] [-m] [<branch>]
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12'git checkout' [-q] [-f] [-m] --detach [<branch>]
13'git checkout' [-q] [-f] [-m] [--detach] <commit>
02ac9837 14'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]
eac5a401 15'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
a31538e2 16'git checkout' [-p|--patch] [<tree-ish>] [--] [<paths>...]
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17
18DESCRIPTION
19-----------
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20Updates files in the working tree to match the version in the index
21or the specified tree. If no paths are given, 'git checkout' will
22also update `HEAD` to set the specified branch as the current
76cfadfc 23branch.
4aaa7027 24
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25'git checkout' <branch>::
26 To prepare for working on <branch>, switch to it by updating
27 the index and the files in the working tree, and by pointing
28 HEAD at the branch. Local modifications to the files in the
29 working tree are kept, so that they can be committed to the
30 <branch>.
31+
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32If <branch> is not found but there does exist a tracking branch in
33exactly one remote (call it <remote>) with a matching name, treat as
34equivalent to
35+
36------------
37$ git checkout -b <branch> --track <remote>/<branch>
38------------
39+
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40You could omit <branch>, in which case the command degenerates to
41"check out the current branch", which is a glorified no-op with a
42rather expensive side-effects to show only the tracking information,
43if exists, for the current branch.
44
02ac9837 45'git checkout' -b|-B <new_branch> [<start point>]::
4aaa7027 46
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47 Specifying `-b` causes a new branch to be created as if
48 linkgit:git-branch[1] were called and then checked out. In
49 this case you can use the `--track` or `--no-track` options,
50 which will be passed to 'git branch'. As a convenience,
51 `--track` without `-b` implies branch creation; see the
52 description of `--track` below.
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53+
54If `-B` is given, <new_branch> is created if it doesn't exist; otherwise, it
55is reset. This is the transactional equivalent of
56+
57------------
58$ git branch -f <branch> [<start point>]
59$ git checkout <branch>
60------------
61+
62that is to say, the branch is not reset/created unless "git checkout" is
63successful.
bb0ceb62 64
e1cdf633 65'git checkout' --detach [<branch>]::
26776c97 66'git checkout' [--detach] <commit>::
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67
68 Prepare to work on top of <commit>, by detaching HEAD at it
69 (see "DETACHED HEAD" section), and updating the index and the
70 files in the working tree. Local modifications to the files
71 in the working tree are kept, so that the resulting working
72 tree will be the state recorded in the commit plus the local
73 modifications.
74+
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75When the <commit> argument is a branch name, the `--detach` option can
76be used to detach HEAD at the tip of the branch (`git checkout
77<branch>` would check out that branch without detaching HEAD).
78+
79Omitting <branch> detaches HEAD at the tip of the current branch.
e1cdf633 80
a31538e2 81'git checkout' [-p|--patch] [<tree-ish>] [--] <pathspec>...::
4aaa7027 82
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83 When <paths> or `--patch` are given, 'git checkout' does *not*
84 switch branches. It updates the named paths in the working tree
85 from the index file or from a named <tree-ish> (most often a
86 commit). In this case, the `-b` and `--track` options are
87 meaningless and giving either of them results in an error. The
88 <tree-ish> argument can be used to specify a specific tree-ish
89 (i.e. commit, tag or tree) to update the index for the given
90 paths before updating the working tree.
c5b41519 91+
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92'git checkout' with <paths> or `--patch` is used to restore modified or
93deleted paths to their original contents from the index or replace paths
94with the contents from a named <tree-ish> (most often a commit-ish).
95+
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96The index may contain unmerged entries because of a previous failed merge.
97By default, if you try to check out such an entry from the index, the
db941099 98checkout operation will fail and nothing will be checked out.
b831deda 99Using `-f` will ignore these unmerged entries. The contents from a
38901a48 100specific side of the merge can be checked out of the index by
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101using `--ours` or `--theirs`. With `-m`, changes made to the working tree
102file can be discarded to re-create the original conflicted merge result.
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103
104OPTIONS
105-------
6124aee5 106-q::
f7aec129 107--quiet::
2be7fcb4 108 Quiet, suppress feedback messages.
6124aee5 109
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110--[no-]progress::
111 Progress status is reported on the standard error stream
112 by default when it is attached to a terminal, unless `--quiet`
113 is specified. This flag enables progress reporting even if not
114 attached to a terminal, regardless of `--quiet`.
115
0270f7c5 116-f::
f7aec129 117--force::
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118 When switching branches, proceed even if the index or the
119 working tree differs from HEAD. This is used to throw away
120 local changes.
121+
122When checking out paths from the index, do not fail upon unmerged
123entries; instead, unmerged entries are ignored.
0270f7c5 124
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125--ours::
126--theirs::
127 When checking out paths from the index, check out stage #2
128 ('ours') or #3 ('theirs') for unmerged paths.
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130Note that during `git rebase` and `git pull --rebase`, 'ours' and
131'theirs' may appear swapped; `--ours` gives the version from the
132branch the changes are rebased onto, while `--theirs` gives the
133version from the branch that holds your work that is being rebased.
134+
135This is because `rebase` is used in a workflow that treats the
136history at the remote as the shared canonical one, and treats the
137work done on the branch you are rebasing as the third-party work to
138be integrated, and you are temporarily assuming the role of the
139keeper of the canonical history during the rebase. As the keeper of
140the canonical history, you need to view the history from the remote
141as `ours` (i.e. "our shared canonical history"), while what you did
142on your side branch as `theirs` (i.e. "one contributor's work on top
143of it").
0270f7c5 144
45aaf031 145-b <new_branch>::
2b1f4247 146 Create a new branch named <new_branch> and start it at
76cfadfc 147 <start_point>; see linkgit:git-branch[1] for details.
7fc9d69f 148
45aaf031 149-B <new_branch>::
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150 Creates the branch <new_branch> and start it at <start_point>;
151 if it already exists, then reset it to <start_point>. This is
152 equivalent to running "git branch" with "-f"; see
153 linkgit:git-branch[1] for details.
154
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155-t::
156--track::
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157 When creating a new branch, set up "upstream" configuration. See
158 "--track" in linkgit:git-branch[1] for details.
bb0ceb62 159+
23f8239b 160If no `-b` option is given, the name of the new branch will be
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161derived from the remote-tracking branch, by looking at the local part of
162the refspec configured for the corresponding remote, and then stripping
163the initial part up to the "*".
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164This would tell us to use "hack" as the local branch when branching
165off of "origin/hack" (or "remotes/origin/hack", or even
166"refs/remotes/origin/hack"). If the given name has no slash, or the above
167guessing results in an empty name, the guessing is aborted. You can
23f8239b 168explicitly give a name with `-b` in such a case.
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169
170--no-track::
167d7445 171 Do not set up "upstream" configuration, even if the
da0005b8 172 branch.autoSetupMerge configuration variable is true.
0746d19a 173
969d326d 174-l::
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175 Create the new branch's reflog; see linkgit:git-branch[1] for
176 details.
969d326d 177
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178--detach::
179 Rather than checking out a branch to work on it, check out a
180 commit for inspection and discardable experiments.
181 This is the default behavior of "git checkout <commit>" when
182 <commit> is not a branch name. See the "DETACHED HEAD" section
183 below for details.
184
45aaf031 185--orphan <new_branch>::
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186 Create a new 'orphan' branch, named <new_branch>, started from
187 <start_point> and switch to it. The first commit made on this
188 new branch will have no parents and it will be the root of a new
189 history totally disconnected from all the other branches and
190 commits.
9db5ebf4 191+
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192The index and the working tree are adjusted as if you had previously run
193"git checkout <start_point>". This allows you to start a new history
194that records a set of paths similar to <start_point> by easily running
195"git commit -a" to make the root commit.
9db5ebf4 196+
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197This can be useful when you want to publish the tree from a commit
198without exposing its full history. You might want to do this to publish
199an open source branch of a project whose current tree is "clean", but
200whose full history contains proprietary or otherwise encumbered bits of
201code.
202+
203If you want to start a disconnected history that records a set of paths
204that is totally different from the one of <start_point>, then you should
205clear the index and the working tree right after creating the orphan
206branch by running "git rm -rf ." from the top level of the working tree.
207Afterwards you will be ready to prepare your new files, repopulating the
208working tree, by copying them from elsewhere, extracting a tarball, etc.
9db5ebf4 209
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210--ignore-skip-worktree-bits::
211 In sparse checkout mode, `git checkout -- <paths>` would
212 update only entries matched by <paths> and sparse patterns
213 in $GIT_DIR/info/sparse-checkout. This option ignores
214 the sparse patterns and adds back any files in <paths>.
215
1be0659e 216-m::
eac5a401 217--merge::
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218 When switching branches,
219 if you have local modifications to one or more files that
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220 are different between the current branch and the branch to
221 which you are switching, the command refuses to switch
222 branches in order to preserve your modifications in context.
223 However, with this option, a three-way merge between the current
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224 branch, your working tree contents, and the new branch
225 is done, and you will be on the new branch.
226+
227When a merge conflict happens, the index entries for conflicting
228paths are left unmerged, and you need to resolve the conflicts
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229and mark the resolved paths with `git add` (or `git rm` if the merge
230should result in deletion of the path).
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231+
232When checking out paths from the index, this option lets you recreate
233the conflicted merge in the specified paths.
1be0659e 234
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235--conflict=<style>::
236 The same as --merge option above, but changes the way the
237 conflicting hunks are presented, overriding the
da0005b8 238 merge.conflictStyle configuration variable. Possible values are
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239 "merge" (default) and "diff3" (in addition to what is shown by
240 "merge" style, shows the original contents).
1be0659e 241
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242-p::
243--patch::
244 Interactively select hunks in the difference between the
245 <tree-ish> (or the index, if unspecified) and the working
246 tree. The chosen hunks are then applied in reverse to the
247 working tree (and if a <tree-ish> was specified, the index).
248+
249This means that you can use `git checkout -p` to selectively discard
a31538e2 250edits from your current working tree. See the ``Interactive Mode''
6cf378f0 251section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
4f353658 252
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253--ignore-other-worktrees::
254 `git checkout` refuses when the wanted ref is already checked
255 out by another worktree. This option makes it check the ref
256 out anyway. In other words, the ref can be held by more than one
257 worktree.
258
0270f7c5 259<branch>::
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260 Branch to checkout; if it refers to a branch (i.e., a name that,
261 when prepended with "refs/heads/", is a valid ref), then that
262 branch is checked out. Otherwise, if it refers to a valid
263 commit, your HEAD becomes "detached" and you are no longer on
264 any branch (see below for details).
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266You can use the `"@{-N}"` syntax to refer to the N-th last
267branch/commit checked out using "git checkout" operation. You may
268also specify `-` which is synonymous to `"@{-1}`.
873c3472 269+
75ce1495 270As a special case, you may use `"A...B"` as a shortcut for the
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271merge base of `A` and `B` if there is exactly one merge base. You can
272leave out at most one of `A` and `B`, in which case it defaults to `HEAD`.
5e1a2e8c 273
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274<new_branch>::
275 Name for the new branch.
276
277<start_point>::
278 The name of a commit at which to start the new branch; see
279 linkgit:git-branch[1] for details. Defaults to HEAD.
280
281<tree-ish>::
282 Tree to checkout from (when paths are given). If not specified,
283 the index will be used.
284
285
5e1a2e8c 286
32669671 287DETACHED HEAD
5e1a2e8c 288-------------
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289HEAD normally refers to a named branch (e.g. 'master'). Meanwhile, each
290branch refers to a specific commit. Let's look at a repo with three
291commits, one of them tagged, and with branch 'master' checked out:
5e1a2e8c 292
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293------------
294 HEAD (refers to branch 'master')
295 |
296 v
297a---b---c branch 'master' (refers to commit 'c')
298 ^
299 |
300 tag 'v2.0' (refers to commit 'b')
301------------
302
303When a commit is created in this state, the branch is updated to refer to
304the new commit. Specifically, 'git commit' creates a new commit 'd', whose
305parent is commit 'c', and then updates branch 'master' to refer to new
306commit 'd'. HEAD still refers to branch 'master' and so indirectly now refers
307to commit 'd':
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308
309------------
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310$ edit; git add; git commit
311
312 HEAD (refers to branch 'master')
313 |
314 v
315a---b---c---d branch 'master' (refers to commit 'd')
316 ^
317 |
318 tag 'v2.0' (refers to commit 'b')
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319------------
320
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321It is sometimes useful to be able to checkout a commit that is not at
322the tip of any named branch, or even to create a new commit that is not
323referenced by a named branch. Let's look at what happens when we
324checkout commit 'b' (here we show two ways this may be done):
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325
326------------
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327$ git checkout v2.0 # or
328$ git checkout master^^
329
330 HEAD (refers to commit 'b')
331 |
332 v
333a---b---c---d branch 'master' (refers to commit 'd')
334 ^
335 |
336 tag 'v2.0' (refers to commit 'b')
337------------
5e1a2e8c 338
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339Notice that regardless of which checkout command we use, HEAD now refers
340directly to commit 'b'. This is known as being in detached HEAD state.
341It means simply that HEAD refers to a specific commit, as opposed to
342referring to a named branch. Let's see what happens when we create a commit:
cec8d146 343
cec8d146 344------------
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345$ edit; git add; git commit
346
347 HEAD (refers to commit 'e')
348 |
349 v
350 e
351 /
352a---b---c---d branch 'master' (refers to commit 'd')
353 ^
354 |
355 tag 'v2.0' (refers to commit 'b')
cec8d146 356------------
7fc9d69f 357
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358There is now a new commit 'e', but it is referenced only by HEAD. We can
359of course add yet another commit in this state:
7fc9d69f 360
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361------------
362$ edit; git add; git commit
363
364 HEAD (refers to commit 'f')
365 |
366 v
367 e---f
368 /
369a---b---c---d branch 'master' (refers to commit 'd')
370 ^
371 |
372 tag 'v2.0' (refers to commit 'b')
373------------
374
2de9b711 375In fact, we can perform all the normal Git operations. But, let's look
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376at what happens when we then checkout master:
377
378------------
379$ git checkout master
380
381 HEAD (refers to branch 'master')
382 e---f |
383 / v
384a---b---c---d branch 'master' (refers to commit 'd')
385 ^
386 |
387 tag 'v2.0' (refers to commit 'b')
388------------
389
390It is important to realize that at this point nothing refers to commit
391'f'. Eventually commit 'f' (and by extension commit 'e') will be deleted
2de9b711 392by the routine Git garbage collection process, unless we create a reference
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393before that happens. If we have not yet moved away from commit 'f',
394any of these will create a reference to it:
395
396------------
397$ git checkout -b foo <1>
398$ git branch foo <2>
399$ git tag foo <3>
400------------
401
402<1> creates a new branch 'foo', which refers to commit 'f', and then
403updates HEAD to refer to branch 'foo'. In other words, we'll no longer
404be in detached HEAD state after this command.
405
406<2> similarly creates a new branch 'foo', which refers to commit 'f',
407but leaves HEAD detached.
408
409<3> creates a new tag 'foo', which refers to commit 'f',
410leaving HEAD detached.
411
412If we have moved away from commit 'f', then we must first recover its object
413name (typically by using git reflog), and then we can create a reference to
414it. For example, to see the last two commits to which HEAD referred, we
415can use either of these commands:
416
417------------
418$ git reflog -2 HEAD # or
419$ git log -g -2 HEAD
420------------
4aaa7027 421
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422ARGUMENT DISAMBIGUATION
423-----------------------
424
425When there is only one argument given and it is not `--` (e.g. "git
426checkout abc"), and when the argument is both a valid `<tree-ish>`
427(e.g. a branch "abc" exists) and a valid `<pathspec>` (e.g. a file
428or a directory whose name is "abc" exists), Git would usually ask
429you to disambiguate. Because checking out a branch is so common an
430operation, however, "git checkout abc" takes "abc" as a `<tree-ish>`
431in such a situation. Use `git checkout -- <pathspec>` if you want
432to checkout these paths out of the index.
433
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434EXAMPLES
435--------
4aaa7027 436
1be0659e 437. The following sequence checks out the `master` branch, reverts
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438the `Makefile` to two revisions back, deletes hello.c by
439mistake, and gets it back from the index.
1be0659e 440+
4aaa7027 441------------
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442$ git checkout master <1>
443$ git checkout master~2 Makefile <2>
4aaa7027 444$ rm -f hello.c
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445$ git checkout hello.c <3>
446------------
447+
1e2ccd3a 448<1> switch branch
c7cb12b8 449<2> take a file out of another commit
ce8936c3 450<3> restore hello.c from the index
1be0659e 451+
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452If you want to check out _all_ C source files out of the index,
453you can say
454+
455------------
456$ git checkout -- '*.c'
457------------
458+
459Note the quotes around `*.c`. The file `hello.c` will also be
460checked out, even though it is no longer in the working tree,
461because the file globbing is used to match entries in the index
462(not in the working tree by the shell).
463+
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464If you have an unfortunate branch that is named `hello.c`, this
465step would be confused as an instruction to switch to that branch.
466You should instead write:
1be0659e 467+
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468------------
469$ git checkout -- hello.c
470------------
471
c7cb12b8 472. After working in the wrong branch, switching to the correct
71bb1033 473branch would be done using:
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474+
475------------
476$ git checkout mytopic
477------------
478+
479However, your "wrong" branch and correct "mytopic" branch may
c7cb12b8 480differ in files that you have modified locally, in which case
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481the above checkout would fail like this:
482+
483------------
484$ git checkout mytopic
142183d0 485error: You have local changes to 'frotz'; not switching branches.
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486------------
487+
488You can give the `-m` flag to the command, which would try a
489three-way merge:
490+
491------------
492$ git checkout -m mytopic
493Auto-merging frotz
494------------
495+
496After this three-way merge, the local modifications are _not_
497registered in your index file, so `git diff` would show you what
498changes you made since the tip of the new branch.
499
500. When a merge conflict happens during switching branches with
501the `-m` option, you would see something like this:
502+
503------------
504$ git checkout -m mytopic
505Auto-merging frotz
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506ERROR: Merge conflict in frotz
507fatal: merge program failed
508------------
509+
510At this point, `git diff` shows the changes cleanly merged as in
511the previous example, as well as the changes in the conflicted
512files. Edit and resolve the conflict and mark it resolved with
d7f078b8 513`git add` as usual:
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514+
515------------
516$ edit frotz
d7f078b8 517$ git add frotz
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518------------
519
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520GIT
521---
9e1f0a85 522Part of the linkgit:git[1] suite