Merge branch 'js/attach'
[git/git.git] / Documentation / git-checkout.txt
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1git-checkout(1)
2===============
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3
4NAME
5----
7bd7f280 6git-checkout - Checkout and switch to a branch
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7
8SYNOPSIS
9--------
71bb1033 10[verse]
6124aee5 11'git-checkout' [-q] [-f] [-b <new_branch> [-l]] [-m] [<branch>]
84a978f1 12'git-checkout' [<tree-ish>] <paths>...
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13
14DESCRIPTION
15-----------
4aaa7027 16
71bb1033 17When <paths> are not given, this command switches branches by
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18updating the index and working tree to reflect the specified
19branch, <branch>, and updating HEAD to be <branch> or, if
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20specified, <new_branch>. Using -b will cause <new_branch> to
21be created.
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22
23When <paths> are given, this command does *not* switch
24branches. It updates the named paths in the working tree from
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25the index file (i.e. it runs `git-checkout-index -f -u`), or a
26named commit. In
4aaa7027 27this case, `-f` and `-b` options are meaningless and giving
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28either of them results in an error. <tree-ish> argument can be
29used to specify a specific tree-ish (i.e. commit, tag or tree)
30to update the index for the given paths before updating the
31working tree.
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33
34OPTIONS
35-------
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NP
36-q::
37 Quiet, supress feedback messages.
38
0270f7c5 39-f::
71bb1033 40 Force a re-read of everything.
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41
42-b::
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43 Create a new branch named <new_branch> and start it at
44 <branch>. The new branch name must pass all checks defined
45 by gitlink:git-check-ref-format[1]. Some of these checks
46 may restrict the characters allowed in a branch name.
7fc9d69f 47
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48-l::
49 Create the new branch's ref log. This activates recording of
50 all changes to made the branch ref, enabling use of date
51 based sha1 expressions such as "<branchname>@{yesterday}".
52
1be0659e 53-m::
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54 If you have local modifications to one or more files that
55 are different between the current branch and the branch to
56 which you are switching, the command refuses to switch
57 branches in order to preserve your modifications in context.
58 However, with this option, a three-way merge between the current
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59 branch, your working tree contents, and the new branch
60 is done, and you will be on the new branch.
61+
62When a merge conflict happens, the index entries for conflicting
63paths are left unmerged, and you need to resolve the conflicts
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64and mark the resolved paths with `git add` (or `git rm` if the merge
65should result in deletion of the path).
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67<new_branch>::
68 Name for the new branch.
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70<branch>::
71 Branch to checkout; may be any object ID that resolves to a
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72 commit. Defaults to HEAD.
73+
74When this parameter names a non-branch (but still a valid commit object),
75your HEAD becomes 'detached'.
76
77
78Detached HEAD
79-------------
80
81It is sometimes useful to be able to 'checkout' a commit that is
82not at the tip of one of your branches. The most obvious
83example is to check out the commit at a tagged official release
84point, like this:
85
86------------
87$ git checkout v2.6.18
88------------
89
90Earlier versions of git did not allow this and asked you to
91create a temporary branch using `-b` option, but starting from
92version 1.5.0, the above command 'detaches' your HEAD from the
93current branch and directly point at the commit named by the tag
94(`v2.6.18` in the above example).
95
96You can use usual git commands while in this state. You can use
97`git-reset --hard $othercommit` to further move around, for
98example. You can make changes and create a new commit on top of
99a detached HEAD. You can even create a merge by using `git
100merge $othercommit`.
101
102The state you are in while your HEAD is detached is not recorded
103by any branch (which is natural --- you are not on any branch).
104What this means is that you can discard your temporary commits
105and merges by switching back to an existing branch (e.g. `git
106checkout master`), and a later `git prune` or `git gc` would
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107garbage-collect them. If you did this by mistake, you can ask
108the reflog for HEAD where you were, e.g.
109
110------------
111$ git log -g -2 HEAD
112------------
7fc9d69f 113
4aaa7027 114
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115EXAMPLES
116--------
4aaa7027 117
1be0659e 118. The following sequence checks out the `master` branch, reverts
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119the `Makefile` to two revisions back, deletes hello.c by
120mistake, and gets it back from the index.
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4aaa7027 122------------
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123$ git checkout master <1>
124$ git checkout master~2 Makefile <2>
4aaa7027 125$ rm -f hello.c
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126$ git checkout hello.c <3>
127------------
128+
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129<1> switch branch
130<2> take out a file out of other commit
48aeecdc 131<3> restore hello.c from HEAD of current branch
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133If you have an unfortunate branch that is named `hello.c`, this
134step would be confused as an instruction to switch to that branch.
135You should instead write:
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137------------
138$ git checkout -- hello.c
139------------
140
1be0659e 141. After working in a wrong branch, switching to the correct
71bb1033 142branch would be done using:
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143+
144------------
145$ git checkout mytopic
146------------
147+
148However, your "wrong" branch and correct "mytopic" branch may
149differ in files that you have locally modified, in which case,
150the above checkout would fail like this:
151+
152------------
153$ git checkout mytopic
154fatal: Entry 'frotz' not uptodate. Cannot merge.
155------------
156+
157You can give the `-m` flag to the command, which would try a
158three-way merge:
159+
160------------
161$ git checkout -m mytopic
162Auto-merging frotz
163------------
164+
165After this three-way merge, the local modifications are _not_
166registered in your index file, so `git diff` would show you what
167changes you made since the tip of the new branch.
168
169. When a merge conflict happens during switching branches with
170the `-m` option, you would see something like this:
171+
172------------
173$ git checkout -m mytopic
174Auto-merging frotz
175merge: warning: conflicts during merge
176ERROR: Merge conflict in frotz
177fatal: merge program failed
178------------
179+
180At this point, `git diff` shows the changes cleanly merged as in
181the previous example, as well as the changes in the conflicted
182files. Edit and resolve the conflict and mark it resolved with
d7f078b8 183`git add` as usual:
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184+
185------------
186$ edit frotz
d7f078b8 187$ git add frotz
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188------------
189
4aaa7027 190
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191Author
192------
193Written by Linus Torvalds <torvalds@osdl.org>
194
195Documentation
196--------------
197Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
198
199GIT
200---
a7154e91 201Part of the gitlink:git[7] suite
7fc9d69f 202