mailinfo: tests for RFC2047 examples
[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] [[--track | --no-track] -b <new_branch> [-l]] [-m] [<branch>]
12 'git checkout' [<tree-ish>] [--] <paths>...
13
14 DESCRIPTION
15 -----------
16
17 When <paths> are not given, this command switches branches by
18 updating the index and working tree to reflect the specified
19 branch, <branch>, and updating HEAD to be <branch> or, if
20 specified, <new_branch>. Using -b will cause <new_branch> to
21 be created; in this case you can use the --track or --no-track
22 options, which will be passed to `git branch`.
23
24 When <paths> are given, this command does *not* switch
25 branches. It updates the named paths in the working tree from
26 the index file (i.e. it runs `git checkout-index -f -u`), or
27 from a named commit. In
28 this case, the `-f` and `-b` options are meaningless and giving
29 either of them results in an error. <tree-ish> argument can be
30 used to specify a specific tree-ish (i.e. commit, tag or tree)
31 to update the index for the given paths before updating the
32 working tree.
33
34
35 OPTIONS
36 -------
37 -q::
38 Quiet, suppress feedback messages.
39
40 -f::
41 Proceed even if the index or the working tree differs
42 from HEAD. This is used to throw away local changes.
43
44 -b::
45 Create a new branch named <new_branch> and start it at
46 <branch>. The new branch name must pass all checks defined
47 by linkgit:git-check-ref-format[1]. Some of these checks
48 may restrict the characters allowed in a branch name.
49
50 -t::
51 --track::
52 When creating a new branch, set up configuration so that 'git-pull'
53 will automatically retrieve data from the start point, which must be
54 a branch. Use this if you always pull from the same upstream branch
55 into the new branch, and if you don't want to use "git pull
56 <repository> <refspec>" explicitly. This behavior is the default
57 when the start point is a remote branch. Set the
58 branch.autosetupmerge configuration variable to `false` if you want
59 'git-checkout' and 'git-branch' to always behave as if '--no-track' were
60 given. Set it to `always` if you want this behavior when the
61 start-point is either a local or remote branch.
62
63 --no-track::
64 Ignore the branch.autosetupmerge configuration variable.
65
66 -l::
67 Create the new branch's reflog. This activates recording of
68 all changes made to the branch ref, enabling use of date
69 based sha1 expressions such as "<branchname>@\{yesterday}".
70
71 -m::
72 If you have local modifications to one or more files that
73 are different between the current branch and the branch to
74 which you are switching, the command refuses to switch
75 branches in order to preserve your modifications in context.
76 However, with this option, a three-way merge between the current
77 branch, your working tree contents, and the new branch
78 is done, and you will be on the new branch.
79 +
80 When a merge conflict happens, the index entries for conflicting
81 paths are left unmerged, and you need to resolve the conflicts
82 and mark the resolved paths with `git add` (or `git rm` if the merge
83 should result in deletion of the path).
84
85 <new_branch>::
86 Name for the new branch.
87
88 <branch>::
89 Branch to checkout; may be any object ID that resolves to a
90 commit. Defaults to HEAD.
91 +
92 When this parameter names a non-branch (but still a valid commit object),
93 your HEAD becomes 'detached'.
94
95
96 Detached HEAD
97 -------------
98
99 It is sometimes useful to be able to 'checkout' a commit that is
100 not at the tip of one of your branches. The most obvious
101 example is to check out the commit at a tagged official release
102 point, like this:
103
104 ------------
105 $ git checkout v2.6.18
106 ------------
107
108 Earlier versions of git did not allow this and asked you to
109 create a temporary branch using `-b` option, but starting from
110 version 1.5.0, the above command 'detaches' your HEAD from the
111 current branch and directly point at the commit named by the tag
112 (`v2.6.18` in the above example).
113
114 You can use usual git commands while in this state. You can use
115 `git reset --hard $othercommit` to further move around, for
116 example. You can make changes and create a new commit on top of
117 a detached HEAD. You can even create a merge by using `git
118 merge $othercommit`.
119
120 The state you are in while your HEAD is detached is not recorded
121 by any branch (which is natural --- you are not on any branch).
122 What this means is that you can discard your temporary commits
123 and merges by switching back to an existing branch (e.g. `git
124 checkout master`), and a later `git prune` or `git gc` would
125 garbage-collect them. If you did this by mistake, you can ask
126 the reflog for HEAD where you were, e.g.
127
128 ------------
129 $ git log -g -2 HEAD
130 ------------
131
132
133 EXAMPLES
134 --------
135
136 . The following sequence checks out the `master` branch, reverts
137 the `Makefile` to two revisions back, deletes hello.c by
138 mistake, and gets it back from the index.
139 +
140 ------------
141 $ git checkout master <1>
142 $ git checkout master~2 Makefile <2>
143 $ rm -f hello.c
144 $ git checkout hello.c <3>
145 ------------
146 +
147 <1> switch branch
148 <2> take out a file out of other commit
149 <3> restore hello.c from HEAD of current branch
150 +
151 If you have an unfortunate branch that is named `hello.c`, this
152 step would be confused as an instruction to switch to that branch.
153 You should instead write:
154 +
155 ------------
156 $ git checkout -- hello.c
157 ------------
158
159 . After working in a wrong branch, switching to the correct
160 branch would be done using:
161 +
162 ------------
163 $ git checkout mytopic
164 ------------
165 +
166 However, your "wrong" branch and correct "mytopic" branch may
167 differ in files that you have locally modified, in which case,
168 the above checkout would fail like this:
169 +
170 ------------
171 $ git checkout mytopic
172 fatal: Entry 'frotz' not uptodate. Cannot merge.
173 ------------
174 +
175 You can give the `-m` flag to the command, which would try a
176 three-way merge:
177 +
178 ------------
179 $ git checkout -m mytopic
180 Auto-merging frotz
181 ------------
182 +
183 After this three-way merge, the local modifications are _not_
184 registered in your index file, so `git diff` would show you what
185 changes you made since the tip of the new branch.
186
187 . When a merge conflict happens during switching branches with
188 the `-m` option, you would see something like this:
189 +
190 ------------
191 $ git checkout -m mytopic
192 Auto-merging frotz
193 merge: warning: conflicts during merge
194 ERROR: Merge conflict in frotz
195 fatal: merge program failed
196 ------------
197 +
198 At this point, `git diff` shows the changes cleanly merged as in
199 the previous example, as well as the changes in the conflicted
200 files. Edit and resolve the conflict and mark it resolved with
201 `git add` as usual:
202 +
203 ------------
204 $ edit frotz
205 $ git add frotz
206 ------------
207
208
209 Author
210 ------
211 Written by Linus Torvalds <torvalds@osdl.org>
212
213 Documentation
214 --------------
215 Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
216
217 GIT
218 ---
219 Part of the linkgit:git[1] suite