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