X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=Documentation%2Fgit-checkout.txt;h=1ae77be45055418b9c784d15db520841dd7bdd7a;hb=fd2a75972e90d34bc8d4bebe1d669645557a2192;hp=095128906a523cc8ca30639c1d42452a4bcb0050;hpb=283c8eef6c9a4e379c73904d2bc22b19341b15c8;p=git.git

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 095128906..1ae77be45 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -8,8 +8,8 @@ git-checkout - Checkout and switch to a branch
 SYNOPSIS
 --------
 [verse]
-'git-checkout' [-f] [-b <new_branch>] [-m] [<branch>]
-'git-checkout' [-m] [<branch>] <paths>...
+'git-checkout' [-q] [-f] [-b <new_branch> [-l]] [-m] [<branch>]
+'git-checkout' [<tree-ish>] <paths>...
 
 DESCRIPTION
 -----------
@@ -22,20 +22,33 @@ be created.
 
 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
+the index file (i.e. it runs `git-checkout-index -f -u`), or a
+named commit.  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.
+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.
 
 -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.
+
+-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
@@ -48,14 +61,55 @@ OPTIONS
 +
 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
@@ -126,11 +180,11 @@ 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 update-index` as usual:
+`git add` as usual:
 +
 ------------
 $ edit frotz
-$ git update-index frotz
+$ git add frotz
 ------------