SYNOPSIS
--------
[verse]
-'git-checkout' [-f] [-b <new_branch>] [-m] [<branch>]
-'git-checkout' [
-m] [<branch>] <paths>...
+'git-checkout' [-q] [-f] [[--track | --no-track] -b <new_branch> [-l]] [-m] [<branch>]
+'git-checkout' [
<tree-ish>] <paths>...
DESCRIPTION
-----------
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.
+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 (i.e. it runs `git-checkout-index -f -u`). In
-this case, `-f` and `-b` options are meaningless and giving
-either of them results in an error. <branch> argument can be
-used to specify a specific tree-ish to update the index for the
-given paths before updating the working tree.
+the index file (i.e. it runs `git-checkout-index -f -u`), or
+from a named commit. In
+this case, the `-f` and `-b` options are 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.
OPTIONS
-------
+-q::
+ Quiet, supress feedback messages.
+
-f::
- Force a re-read of everything.
+ 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 and start it at <branch>.
+ Create a new branch named <new_branch> and start it at
+ <branch>. The new branch name must pass all checks defined
+ by gitlink:git-check-ref-format[1]. Some of these checks
+ may restrict the characters allowed in a branch name.
+
+--track::
+ When -b is given and a branch is created off a remote branch,
+ set up configuration so that git-pull will automatically
+ retrieve data from the remote branch. Set the
+ branch.autosetupmerge configuration variable to true if you
+ want git-checkout and git-branch to always behave as if
+ '--track' were given.
+
+--no-track::
+ When -b is given and a branch is created off a remote branch,
+ set up configuration so that git-pull will not retrieve data
+ from the remote branch, ignoring the branch.autosetupmerge
+ configuration variable.
+
+-l::
+ Create the new branch's ref log. This activates recording of
+ all changes to made the branch ref, enabling use of date
+ based sha1 expressions such as "<branchname>@{yesterday}".
-m::
If you have local modifications to one or more files that
+
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 update-index`.
+and mark the resolved paths with `git add` (or `git rm` if the merge
+should result in deletion of the path).
<new_branch>::
Name for the new branch.
<branch>::
Branch to checkout; may be any object ID that resolves to a
- commit. Defaults to HEAD.
+ commit. Defaults to HEAD.
++
+When this parameter names a non-branch (but still a valid commit object),
+your HEAD becomes 'detached'.
+
+
+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
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 update-index` as usual:
+`git add` as usual:
+
------------
$ edit frotz
-$ git update-index frotz
+$ git add frotz
------------