Documentation / git-checkout.txton commit gitweb: Update and improve gitweb/README file (61fd255)
   1git-checkout(1)
   2===============
   3
   4NAME
   5----
   6git-checkout - Checkout and switch to a branch
   7
   8SYNOPSIS
   9--------
  10[verse]
  11'git-checkout' [-q] [-f] [[--track | --no-track] -b <new_branch> [-l]] [-m] [<branch>]
  12'git-checkout' [<tree-ish>] <paths>...
  13
  14DESCRIPTION
  15-----------
  16
  17When <paths> are not given, this command switches branches by
  18updating the index and working tree to reflect the specified
  19branch, <branch>, and updating HEAD to be <branch> or, if
  20specified, <new_branch>.  Using -b will cause <new_branch> to
  21be created; in this case you can use the --track or --no-track
  22options, which will be passed to `git branch`.
  23
  24When <paths> are given, this command does *not* switch
  25branches.  It updates the named paths in the working tree from
  26the index file (i.e. it runs `git-checkout-index -f -u`), or
  27from a named commit.  In
  28this case, the `-f` and `-b` options are meaningless and giving
  29either of them results in an error.  <tree-ish> argument can be
  30used to specify a specific tree-ish (i.e. commit, tag or tree)
  31to update the index for the given paths before updating the
  32working tree.
  33
  34
  35OPTIONS
  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 gitlink:git-check-ref-format[1].  Some of these checks
  48        may restrict the characters allowed in a branch name.
  49
  50--track::
  51        When -b is given and a branch is created off a remote branch,
  52        set up configuration so that git-pull will automatically
  53        retrieve data from the remote branch.  Use this if you always
  54        pull from the same remote branch into the new branch, or if you
  55        don't want to use "git pull <repository> <refspec>" explicitly.  Set the
  56        branch.autosetupmerge configuration variable to true if you
  57        want git-checkout and git-branch to always behave as if
  58        '--track' were given.
  59
  60--no-track::
  61        When -b is given and a branch is created off a remote branch,
  62        set up configuration so that git-pull will not retrieve data
  63        from the remote branch, ignoring the branch.autosetupmerge
  64        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+
  80When a merge conflict happens, the index entries for conflicting
  81paths are left unmerged, and you need to resolve the conflicts
  82and mark the resolved paths with `git add` (or `git rm` if the merge
  83should 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+
  92When this parameter names a non-branch (but still a valid commit object),
  93your HEAD becomes 'detached'.
  94
  95
  96Detached HEAD
  97-------------
  98
  99It is sometimes useful to be able to 'checkout' a commit that is
 100not at the tip of one of your branches.  The most obvious
 101example is to check out the commit at a tagged official release
 102point, like this:
 103
 104------------
 105$ git checkout v2.6.18
 106------------
 107
 108Earlier versions of git did not allow this and asked you to
 109create a temporary branch using `-b` option, but starting from
 110version 1.5.0, the above command 'detaches' your HEAD from the
 111current branch and directly point at the commit named by the tag
 112(`v2.6.18` in the above example).
 113
 114You can use usual git commands while in this state.  You can use
 115`git-reset --hard $othercommit` to further move around, for
 116example.  You can make changes and create a new commit on top of
 117a detached HEAD.  You can even create a merge by using `git
 118merge $othercommit`.
 119
 120The state you are in while your HEAD is detached is not recorded
 121by any branch (which is natural --- you are not on any branch).
 122What this means is that you can discard your temporary commits
 123and merges by switching back to an existing branch (e.g. `git
 124checkout master`), and a later `git prune` or `git gc` would
 125garbage-collect them.  If you did this by mistake, you can ask
 126the reflog for HEAD where you were, e.g.
 127
 128------------
 129$ git log -g -2 HEAD
 130------------
 131
 132
 133EXAMPLES
 134--------
 135
 136. The following sequence checks out the `master` branch, reverts
 137the `Makefile` to two revisions back, deletes hello.c by
 138mistake, 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+
 151If you have an unfortunate branch that is named `hello.c`, this
 152step would be confused as an instruction to switch to that branch.
 153You should instead write:
 154+
 155------------
 156$ git checkout -- hello.c
 157------------
 158
 159. After working in a wrong branch, switching to the correct
 160branch would be done using:
 161+
 162------------
 163$ git checkout mytopic
 164------------
 165+
 166However, your "wrong" branch and correct "mytopic" branch may
 167differ in files that you have locally modified, in which case,
 168the above checkout would fail like this:
 169+
 170------------
 171$ git checkout mytopic
 172fatal: Entry 'frotz' not uptodate. Cannot merge.
 173------------
 174+
 175You can give the `-m` flag to the command, which would try a
 176three-way merge:
 177+
 178------------
 179$ git checkout -m mytopic
 180Auto-merging frotz
 181------------
 182+
 183After this three-way merge, the local modifications are _not_
 184registered in your index file, so `git diff` would show you what
 185changes you made since the tip of the new branch.
 186
 187. When a merge conflict happens during switching branches with
 188the `-m` option, you would see something like this:
 189+
 190------------
 191$ git checkout -m mytopic
 192Auto-merging frotz
 193merge: warning: conflicts during merge
 194ERROR: Merge conflict in frotz
 195fatal: merge program failed
 196------------
 197+
 198At this point, `git diff` shows the changes cleanly merged as in
 199the previous example, as well as the changes in the conflicted
 200files.  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
 209Author
 210------
 211Written by Linus Torvalds <torvalds@osdl.org>
 212
 213Documentation
 214--------------
 215Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
 216
 217GIT
 218---
 219Part of the gitlink:git[7] suite