SYNOPSIS
--------
[verse]
-'git checkout' [-q] [-f] [[--track | --no-track] -b <new_branch> [-l]] [-m] [<branch>]
+'git checkout' [-q] [-f] [-m] [<branch>]
+'git checkout' [-q] [-f] [-m] [--detach] [<commit>]
+'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]
'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
+'git checkout' [-p|--patch] [<tree-ish>] [--] [<paths>...]
DESCRIPTION
-----------
+Updates files in the working tree to match the version in the index
+or the specified tree. If no paths are given, 'git checkout' will
+also update `HEAD` to set the specified branch as the current
+branch.
-When <paths> are not given, this command switches branches by
-updating the index and working tree to reflect the specified
-branch, <branch>, and updating HEAD to be <branch> or, if
-specified, <new_branch>. Using -b will cause <new_branch> to
-be created; in this case you can use the --track or --no-track
-options, which will be passed to `git branch`.
-
-When <paths> are given, this command does *not* switch
-branches. It updates the named paths in the working tree from
-the index file, or from a named commit. In
-this case, the `-b` options is meaningless and giving
-either of them results in an error. <tree-ish> argument can be
-used to specify a specific tree-ish (i.e. commit, tag or tree)
-to update the index for the given paths before updating the
-working tree.
-
-The index may contain unmerged entries after a failed merge. By
-default, if you try to check out such an entry from the index, the
+'git checkout' [<branch>]::
+'git checkout' -b|-B <new_branch> [<start point>]::
+'git checkout' [--detach] [<commit>]::
+
+ This form switches branches by updating the index, working
+ tree, and HEAD to reflect the specified branch or commit.
++
+If `-b` is given, a new branch is created as if linkgit:git-branch[1]
+were called and then checked out; in this case you can
+use the `--track` or `--no-track` options, which will be passed to
+'git branch'. As a convenience, `--track` without `-b` implies branch
+creation; see the description of `--track` below.
++
+If `-B` is given, <new_branch> is created if it doesn't exist; otherwise, it
+is reset. This is the transactional equivalent of
++
+------------
+$ git branch -f <branch> [<start point>]
+$ git checkout <branch>
+------------
++
+that is to say, the branch is not reset/created unless "git checkout" is
+successful.
+
+'git checkout' [-p|--patch] [<tree-ish>] [--] <pathspec>...::
+
+ When <paths> or `--patch` are given, 'git checkout' does *not*
+ switch branches. It updates the named paths in the working tree
+ from the index file or from a named <tree-ish> (most often a
+ commit). In this case, the `-b` and `--track` options are
+ meaningless and giving either of them results in an error. The
+ <tree-ish> argument can be used to specify a specific tree-ish
+ (i.e. commit, tag or tree) to update the index for the given
+ paths before updating the working tree.
++
+The index may contain unmerged entries because of a previous failed merge.
+By default, if you try to check out such an entry from the index, the
checkout operation will fail and nothing will be checked out.
-Using -f will ignore these unmerged entries. The contents from a
+Using `-f` will ignore these unmerged entries. The contents from a
specific side of the merge can be checked out of the index by
-using --ours or --theirs. With -m, changes made to the working tree
-file can be discarded to recreate the original conflicted merge result.
+using `--ours` or `--theirs`. With `-m`, changes made to the working tree
+file can be discarded to re-create the original conflicted merge result.
OPTIONS
-------
-q::
+--quiet::
Quiet, suppress feedback messages.
-f::
+--force::
When switching branches, proceed even if the index or the
working tree differs from HEAD. This is used to throw away
local changes.
-b::
Create a new branch named <new_branch> and start it at
- <branch>. The new branch name must pass all checks defined
- by linkgit:git-check-ref-format[1]. Some of these checks
- may restrict the characters allowed in a branch name.
+ <start_point>; see linkgit:git-branch[1] for details.
+
+-B::
+ Creates the branch <new_branch> and start it at <start_point>;
+ if it already exists, then reset it to <start_point>. This is
+ equivalent to running "git branch" with "-f"; see
+ linkgit:git-branch[1] for details.
-t::
--track::
- When creating a new branch, set up configuration so that 'git-pull'
- will automatically retrieve data from the start point, which must be
- a branch. Use this if you always pull from the same upstream branch
- into the new branch, and if you don't want to use "git pull
- <repository> <refspec>" explicitly. This behavior is the default
- when the start point is a remote branch. Set the
- branch.autosetupmerge configuration variable to `false` if you want
- 'git-checkout' and 'git-branch' to always behave as if '--no-track' were
- given. Set it to `always` if you want this behavior when the
- start-point is either a local or remote branch.
+ When creating a new branch, set up "upstream" configuration. See
+ "--track" in linkgit:git-branch[1] for details.
++
+If no '-b' option is given, the name of the new branch will be
+derived from the remote-tracking branch. If "remotes/" or "refs/remotes/"
+is prefixed it is stripped away, and then the part up to the
+next slash (which would be the nickname of the remote) is removed.
+This would tell us to use "hack" as the local branch when branching
+off of "origin/hack" (or "remotes/origin/hack", or even
+"refs/remotes/origin/hack"). If the given name has no slash, or the above
+guessing results in an empty name, the guessing is aborted. You can
+explicitly give a name with '-b' in such a case.
--no-track::
- Ignore the branch.autosetupmerge configuration variable.
+ Do not set up "upstream" configuration, even if the
+ branch.autosetupmerge configuration variable is true.
-l::
- Create the new branch's reflog. This activates recording of
- all changes made to the branch ref, enabling use of date
- based sha1 expressions such as "<branchname>@\{yesterday}".
+ Create the new branch's reflog; see linkgit:git-branch[1] for
+ details.
+
+--detach::
+ Rather than checking out a branch to work on it, check out a
+ commit for inspection and discardable experiments.
+ This is the default behavior of "git checkout <commit>" when
+ <commit> is not a branch name. See the "DETACHED HEAD" section
+ below for details.
+
+--orphan::
+ Create a new 'orphan' branch, named <new_branch>, started from
+ <start_point> and switch to it. The first commit made on this
+ new branch will have no parents and it will be the root of a new
+ history totally disconnected from all the other branches and
+ commits.
++
+The index and the working tree are adjusted as if you had previously run
+"git checkout <start_point>". This allows you to start a new history
+that records a set of paths similar to <start_point> by easily running
+"git commit -a" to make the root commit.
++
+This can be useful when you want to publish the tree from a commit
+without exposing its full history. You might want to do this to publish
+an open source branch of a project whose current tree is "clean", but
+whose full history contains proprietary or otherwise encumbered bits of
+code.
++
+If you want to start a disconnected history that records a set of paths
+that is totally different from the one of <start_point>, then you should
+clear the index and the working tree right after creating the orphan
+branch by running "git rm -rf ." from the top level of the working tree.
+Afterwards you will be ready to prepare your new files, repopulating the
+working tree, by copying them from elsewhere, extracting a tarball, etc.
-m::
--merge::
"merge" (default) and "diff3" (in addition to what is shown by
"merge" style, shows the original contents).
-<new_branch>::
- Name for the new branch.
+-p::
+--patch::
+ Interactively select hunks in the difference between the
+ <tree-ish> (or the index, if unspecified) and the working
+ tree. The chosen hunks are then applied in reverse to the
+ working tree (and if a <tree-ish> was specified, the index).
++
+This means that you can use `git checkout -p` to selectively discard
+edits from your current working tree. See the ``Interactive Mode''
+section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
<branch>::
- Branch to checkout; may be any object ID that resolves to a
- commit. Defaults to HEAD.
+ Branch to checkout; if it refers to a branch (i.e., a name that,
+ when prepended with "refs/heads/", is a valid ref), then that
+ branch is checked out. Otherwise, if it refers to a valid
+ commit, your HEAD becomes "detached" and you are no longer on
+ any branch (see below for details).
++
+As a special case, the `"@{-N}"` syntax for the N-th last branch
+checks out the branch (instead of detaching). You may also specify
+`-` which is synonymous with `"@{-1}"`.
+
-When this parameter names a non-branch (but still a valid commit object),
-your HEAD becomes 'detached'.
+As a further special case, you may use `"A...B"` as a shortcut for the
+merge base of `A` and `B` if there is exactly one merge base. You can
+leave out at most one of `A` and `B`, in which case it defaults to `HEAD`.
+
+<new_branch>::
+ Name for the new branch.
+<start_point>::
+ The name of a commit at which to start the new branch; see
+ linkgit:git-branch[1] for details. Defaults to HEAD.
-Detached HEAD
+<tree-ish>::
+ Tree to checkout from (when paths are given). If not specified,
+ the index will be used.
+
+
+
+DETACHED HEAD
-------------
+HEAD normally refers to a named branch (e.g. 'master'). Meanwhile, each
+branch refers to a specific commit. Let's look at a repo with three
+commits, one of them tagged, and with branch 'master' checked out:
+
+------------
+ HEAD (refers to branch 'master')
+ |
+ v
+a---b---c branch 'master' (refers to commit 'c')
+ ^
+ |
+ tag 'v2.0' (refers to commit 'b')
+------------
-It is sometimes useful to be able to 'checkout' a commit that is
-not at the tip of one of your branches. The most obvious
-example is to check out the commit at a tagged official release
-point, like this:
+When a commit is created in this state, the branch is updated to refer to
+the new commit. Specifically, 'git commit' creates a new commit 'd', whose
+parent is commit 'c', and then updates branch 'master' to refer to new
+commit 'd'. HEAD still refers to branch 'master' and so indirectly now refers
+to commit 'd':
------------
-$ git checkout v2.6.18
+$ edit; git add; git commit
+
+ HEAD (refers to branch 'master')
+ |
+ v
+a---b---c---d branch 'master' (refers to commit 'd')
+ ^
+ |
+ tag 'v2.0' (refers to commit 'b')
------------
-Earlier versions of git did not allow this and asked you to
-create a temporary branch using `-b` option, but starting from
-version 1.5.0, the above command 'detaches' your HEAD from the
-current branch and directly point at the commit named by the tag
-(`v2.6.18` in the above example).
+It is sometimes useful to be able to checkout a commit that is not at
+the tip of any named branch, or even to create a new commit that is not
+referenced by a named branch. Let's look at what happens when we
+checkout commit 'b' (here we show two ways this may be done):
-You can use usual git commands while in this state. You can use
-`git reset --hard $othercommit` to further move around, for
-example. You can make changes and create a new commit on top of
-a detached HEAD. You can even create a merge by using `git
-merge $othercommit`.
+------------
+$ git checkout v2.0 # or
+$ git checkout master^^
+
+ HEAD (refers to commit 'b')
+ |
+ v
+a---b---c---d branch 'master' (refers to commit 'd')
+ ^
+ |
+ tag 'v2.0' (refers to commit 'b')
+------------
-The state you are in while your HEAD is detached is not recorded
-by any branch (which is natural --- you are not on any branch).
-What this means is that you can discard your temporary commits
-and merges by switching back to an existing branch (e.g. `git
-checkout master`), and a later `git prune` or `git gc` would
-garbage-collect them. If you did this by mistake, you can ask
-the reflog for HEAD where you were, e.g.
+Notice that regardless of which checkout command we use, HEAD now refers
+directly to commit 'b'. This is known as being in detached HEAD state.
+It means simply that HEAD refers to a specific commit, as opposed to
+referring to a named branch. Let's see what happens when we create a commit:
------------
-$ git log -g -2 HEAD
+$ edit; git add; git commit
+
+ HEAD (refers to commit 'e')
+ |
+ v
+ e
+ /
+a---b---c---d branch 'master' (refers to commit 'd')
+ ^
+ |
+ tag 'v2.0' (refers to commit 'b')
+------------
+
+There is now a new commit 'e', but it is referenced only by HEAD. We can
+of course add yet another commit in this state:
+
+------------
+$ edit; git add; git commit
+
+ HEAD (refers to commit 'f')
+ |
+ v
+ e---f
+ /
+a---b---c---d branch 'master' (refers to commit 'd')
+ ^
+ |
+ tag 'v2.0' (refers to commit 'b')
------------
+In fact, we can perform all the normal git operations. But, let's look
+at what happens when we then checkout master:
+
+------------
+$ git checkout master
+
+ HEAD (refers to branch 'master')
+ e---f |
+ / v
+a---b---c---d branch 'master' (refers to commit 'd')
+ ^
+ |
+ tag 'v2.0' (refers to commit 'b')
+------------
+
+It is important to realize that at this point nothing refers to commit
+'f'. Eventually commit 'f' (and by extension commit 'e') will be deleted
+by the routine git garbage collection process, unless we create a reference
+before that happens. If we have not yet moved away from commit 'f',
+any of these will create a reference to it:
+
+------------
+$ git checkout -b foo <1>
+$ git branch foo <2>
+$ git tag foo <3>
+------------
+
+<1> creates a new branch 'foo', which refers to commit 'f', and then
+updates HEAD to refer to branch 'foo'. In other words, we'll no longer
+be in detached HEAD state after this command.
+
+<2> similarly creates a new branch 'foo', which refers to commit 'f',
+but leaves HEAD detached.
+
+<3> creates a new tag 'foo', which refers to commit 'f',
+leaving HEAD detached.
+
+If we have moved away from commit 'f', then we must first recover its object
+name (typically by using git reflog), and then we can create a reference to
+it. For example, to see the last two commits to which HEAD referred, we
+can use either of these commands:
+
+------------
+$ git reflog -2 HEAD # or
+$ git log -g -2 HEAD
+------------
EXAMPLES
--------
------------
+
<1> switch branch
-<2> take out a file out of other commit
-<3> restore hello.c from HEAD of current branch
+<2> take a file out of another commit
+<3> restore hello.c from the index
+
If you have an unfortunate branch that is named `hello.c`, this
step would be confused as an instruction to switch to that branch.
$ git checkout -- hello.c
------------
-. After working in a wrong branch, switching to the correct
+. After working in the wrong branch, switching to the correct
branch would be done using:
+
------------
------------
+
However, your "wrong" branch and correct "mytopic" branch may
-differ in files that you have locally modified, in which case,
+differ in files that you have modified locally, in which case
the above checkout would fail like this:
+
------------
$ git checkout mytopic
-fatal: Entry 'frotz' not uptodate. Cannot merge.
+error: You have local changes to 'frotz'; not switching branches.
------------
+
You can give the `-m` flag to the command, which would try a
------------
$ git checkout -m mytopic
Auto-merging frotz
-merge: warning: conflicts during merge
ERROR: Merge conflict in frotz
fatal: merge program failed
------------
$ git add frotz
------------
-
-Author
-------
-Written by Linus Torvalds <torvalds@osdl.org>
-
-Documentation
---------------
-Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>.
-
GIT
---
Part of the linkgit:git[1] suite