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git-checkout

NAME

git-checkout - Checkout a branch or paths to the working tree

SYNOPSIS

 git checkout [-q] [-f] [--track | --no-track] [-b <new_branch> [-l]] [-m] [<branch>]
 git checkout [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
 

DESCRIPTION

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.

As a convenience, --track will default to create a branch whose name is constructed from the specified branch name by stripping the first namespace level.

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 <tree-ish> (most often a 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 checkout operation will fail and nothing will be checked out. 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.

OPTIONS

-q

Quiet, suppress feedback messages.

-f

When switching branches, proceed even if the index or the working tree differs from HEAD. This is used to throw away local changes.
When checking out paths from the index, do not fail upon unmerged entries; instead, unmerged entries are ignored.

--ours, --theirs

When checking out paths from the index, check out stage #2 (ours) or #3 (theirs) for unmerged paths.

-b

Create a new branch named <new_branch> and start it at <branch>. The new branch name must pass all checks defined by git-check-ref-format(1). Some of these checks may restrict the characters allowed in a branch name.

-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.
If no -b option was given, the name of the new branch will be derived from the remote branch, by attempting to guess the name of the branch on remote system. If "remotes/" or "refs/remotes/" are 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.

-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}".

-m, --merge

When switching branches, if you have local modifications to one or more files that are different between the current branch and the branch to which you are switching, the command refuses to switch branches in order to preserve your modifications in context. However, with this option, a three-way merge between the current branch, your working tree contents, and the new branch is done, and you will be on the new branch.
When a merge conflict happens, the index entries for conflicting paths are left unmerged, and you need to resolve the conflicts and mark the resolved paths with git add (or git rm if the merge should result in deletion of the path).
When checking out paths from the index, this option lets you recreate the conflicted merge in the specified paths.

--conflict=<style>

The same as --merge option above, but changes the way the conflicting hunks are presented, overriding the merge.conflictstyle configuration variable. Possible values are "merge" (default) and "diff3" (in addition to what is shown by "merge" style, shows the original contents).

<new_branch>

Name for the new branch.

<branch>

Branch to checkout; may be any object ID that resolves to a commit. Defaults to HEAD.
When this parameter names a non-branch (but still a valid commit object), your HEAD becomes detached.
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}".

DETACHED HEAD

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:

 
 $ git checkout v2.6.18
 
 

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).

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.

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.

 
 $ git log -g -2 HEAD
 
 

EXAMPLES

1. The following sequence checks out the master branch, reverts the Makefile to two revisions back, deletes hello.c by mistake, and gets it back from the index.

 
 $ git checkout master             (1)
 $ git checkout master~2 Makefile  (2)
 $ rm -f hello.c
 $ git checkout hello.c            (3)
 
 

1. switch branch
2. take out a file out of other commit
3. restore hello.c from HEAD of current branch

If you have an unfortunate branch that is named hello.c, this step would be confused as an instruction to switch to that branch. You should instead write:

 
 $ git checkout -- hello.c
 
 

2. After working in a wrong branch, switching to the correct branch would be done using:

 
 $ git checkout mytopic
 
 

However, your "wrong" branch and correct "mytopic" branch may differ in files that you have locally modified, in which case, the above checkout would fail like this:

 
 $ git checkout mytopic
 fatal: Entry 'frotz' not uptodate. Cannot merge.
 
 

You can give the -m flag to the command, which would try a three-way merge:

 
 $ git checkout -m mytopic
 Auto-merging frotz
 
 

After this three-way merge, the local modifications are not registered in your index file, so git diff would show you what changes you made since the tip of the new branch.

3. When a merge conflict happens during switching branches with the -m option, you would see something like this:

 
 $ git checkout -m mytopic
 Auto-merging frotz
 ERROR: Merge conflict in frotz
 fatal: merge program failed
 
 

At this point, git diff shows the changes cleanly merged as in the previous example, as well as the changes in the conflicted files. Edit and resolve the conflict and mark it resolved with git add as usual:

 
 $ edit frotz
 $ 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 git(1) suite