Documentation / git-checkout.txton commit receive-pack: allow using --strict mode for unpacking objects (20dc001)
   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 linkgit:git-check-ref-format[1].  Some of these checks
  48        may restrict the characters allowed in a branch name.
  49
  50--track::
  51        When creating a new branch, set up configuration so that git-pull
  52        will automatically retrieve data from the start point, which must be
  53        a branch. Use this if you always pull from the same upstream branch
  54        into the new branch, and if you don't want to use "git pull
  55        <repository> <refspec>" explicitly. This behavior is the default
  56        when the start point is a remote branch. Set the
  57        branch.autosetupmerge configuration variable to `false` if you want
  58        git-checkout and git-branch to always behave as if '--no-track' were
  59        given. Set it to `always` if you want this behavior when the
  60        start-point is either a local or remote branch.
  61
  62--no-track::
  63        Ignore the branch.autosetupmerge configuration variable.
  64
  65-l::
  66        Create the new branch's reflog.  This activates recording of
  67        all changes made to the branch ref, enabling use of date
  68        based sha1 expressions such as "<branchname>@\{yesterday}".
  69
  70-m::
  71        If you have local modifications to one or more files that
  72        are different between the current branch and the branch to
  73        which you are switching, the command refuses to switch
  74        branches in order to preserve your modifications in context.
  75        However, with this option, a three-way merge between the current
  76        branch, your working tree contents, and the new branch
  77        is done, and you will be on the new branch.
  78+
  79When a merge conflict happens, the index entries for conflicting
  80paths are left unmerged, and you need to resolve the conflicts
  81and mark the resolved paths with `git add` (or `git rm` if the merge
  82should result in deletion of the path).
  83
  84<new_branch>::
  85        Name for the new branch.
  86
  87<branch>::
  88        Branch to checkout; may be any object ID that resolves to a
  89        commit.  Defaults to HEAD.
  90+
  91When this parameter names a non-branch (but still a valid commit object),
  92your HEAD becomes 'detached'.
  93
  94
  95Detached HEAD
  96-------------
  97
  98It is sometimes useful to be able to 'checkout' a commit that is
  99not at the tip of one of your branches.  The most obvious
 100example is to check out the commit at a tagged official release
 101point, like this:
 102
 103------------
 104$ git checkout v2.6.18
 105------------
 106
 107Earlier versions of git did not allow this and asked you to
 108create a temporary branch using `-b` option, but starting from
 109version 1.5.0, the above command 'detaches' your HEAD from the
 110current branch and directly point at the commit named by the tag
 111(`v2.6.18` in the above example).
 112
 113You can use usual git commands while in this state.  You can use
 114`git-reset --hard $othercommit` to further move around, for
 115example.  You can make changes and create a new commit on top of
 116a detached HEAD.  You can even create a merge by using `git
 117merge $othercommit`.
 118
 119The state you are in while your HEAD is detached is not recorded
 120by any branch (which is natural --- you are not on any branch).
 121What this means is that you can discard your temporary commits
 122and merges by switching back to an existing branch (e.g. `git
 123checkout master`), and a later `git prune` or `git gc` would
 124garbage-collect them.  If you did this by mistake, you can ask
 125the reflog for HEAD where you were, e.g.
 126
 127------------
 128$ git log -g -2 HEAD
 129------------
 130
 131
 132EXAMPLES
 133--------
 134
 135. The following sequence checks out the `master` branch, reverts
 136the `Makefile` to two revisions back, deletes hello.c by
 137mistake, and gets it back from the index.
 138+
 139------------
 140$ git checkout master             <1>
 141$ git checkout master~2 Makefile  <2>
 142$ rm -f hello.c
 143$ git checkout hello.c            <3>
 144------------
 145+
 146<1> switch branch
 147<2> take out a file out of other commit
 148<3> restore hello.c from HEAD of current branch
 149+
 150If you have an unfortunate branch that is named `hello.c`, this
 151step would be confused as an instruction to switch to that branch.
 152You should instead write:
 153+
 154------------
 155$ git checkout -- hello.c
 156------------
 157
 158. After working in a wrong branch, switching to the correct
 159branch would be done using:
 160+
 161------------
 162$ git checkout mytopic
 163------------
 164+
 165However, your "wrong" branch and correct "mytopic" branch may
 166differ in files that you have locally modified, in which case,
 167the above checkout would fail like this:
 168+
 169------------
 170$ git checkout mytopic
 171fatal: Entry 'frotz' not uptodate. Cannot merge.
 172------------
 173+
 174You can give the `-m` flag to the command, which would try a
 175three-way merge:
 176+
 177------------
 178$ git checkout -m mytopic
 179Auto-merging frotz
 180------------
 181+
 182After this three-way merge, the local modifications are _not_
 183registered in your index file, so `git diff` would show you what
 184changes you made since the tip of the new branch.
 185
 186. When a merge conflict happens during switching branches with
 187the `-m` option, you would see something like this:
 188+
 189------------
 190$ git checkout -m mytopic
 191Auto-merging frotz
 192merge: warning: conflicts during merge
 193ERROR: Merge conflict in frotz
 194fatal: merge program failed
 195------------
 196+
 197At this point, `git diff` shows the changes cleanly merged as in
 198the previous example, as well as the changes in the conflicted
 199files.  Edit and resolve the conflict and mark it resolved with
 200`git add` as usual:
 201+
 202------------
 203$ edit frotz
 204$ git add frotz
 205------------
 206
 207
 208Author
 209------
 210Written by Linus Torvalds <torvalds@osdl.org>
 211
 212Documentation
 213--------------
 214Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
 215
 216GIT
 217---
 218Part of the linkgit:git[7] suite