checkout: support checking out into a new working directory
"git checkout --to" sets up a new working directory with a .git file
pointing to $GIT_DIR/worktrees/<id>. It then executes "git checkout"
again on the new worktree with the same arguments except "--to" is
taken out. The second checkout execution, which is not contaminated
with any info from the current repository, will actually check out and
everything that normal "git checkout" does.
Helped-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 33ad2ad..c101575 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -225,6 +225,13 @@
edits from your current working tree. See the ``Interactive Mode''
section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
+--to=<path>::
+ Check out a branch in a separate working directory at
+ `<path>`. A new working directory is linked to the current
+ repository, sharing everything except working directory
+ specific files such as HEAD, index... See "MULTIPLE WORKING
+ TREES" section for more information.
+
<branch>::
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
@@ -388,6 +395,45 @@
$ git log -g -2 HEAD
------------
+MULTIPLE WORKING TREES
+----------------------
+
+A git repository can support multiple working trees, allowing you to check
+out more than one branch at a time. With `git checkout --to` a new working
+tree is associated with the repository. This new working tree is called a
+"linked working tree" as opposed to the "main working tree" prepared by "git
+init" or "git clone". A repository has one main working tree (if it's not a
+bare repository) and zero or more linked working trees.
+
+Each linked working tree has a private sub-directory in the repository's
+$GIT_DIR/worktrees directory. The private sub-directory's name is usually
+the base name of the linked working tree's path, possibly appended with a
+number to make it unique. For example, when `$GIT_DIR=/path/main/.git` the
+command `git checkout --to /path/other/test-next next` creates the linked
+working tree in `/path/other/test-next` and also creates a
+`$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
+if `test-next` is already taken).
+
+Within a linked working tree, $GIT_DIR is set to point to this private
+directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
+$GIT_COMMON_DIR is set to point back to the main working tree's $GIT_DIR
+(e.g. `/path/main/.git`). These settings are made in a `.git` file located at
+the top directory of the linked working tree.
+
+Path resolution via `git rev-parse --git-path` uses either
+$GIT_DIR or $GIT_COMMON_DIR depending on the path. For example, in the
+linked working tree `git rev-parse --git-path HEAD` returns
+`/path/main/.git/worktrees/test-next/HEAD` (not
+`/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
+rev-parse --git-path refs/heads/master` uses
+$GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
+since refs are shared across all working trees.
+
+See linkgit:gitrepository-layout[5] for more information. The rule of
+thumb is do not make any assumption about whether a path belongs to
+$GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
+inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
+
EXAMPLES
--------
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 96354af..0c2dcfa 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -813,7 +813,8 @@
If this variable is set to a path, non-worktree files that are
normally in $GIT_DIR will be taken from this path
instead. Worktree-specific files such as HEAD or index are
- taken from $GIT_DIR. See linkgit:gitrepository-layout[5] for
+ taken from $GIT_DIR. See linkgit:gitrepository-layout[5] and
+ the section 'MULTIPLE CHECKOUT MODE' in linkgit:checkout[1]
details. This variable has lower precedence than other path
variables such as GIT_INDEX_FILE, GIT_OBJECT_DIRECTORY...
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index 2dc5667..8228450 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -252,6 +252,13 @@
directory is ignored if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/modules" will be used instead.
+worktrees::
+ Contains worktree specific information of linked
+ checkouts. Each subdirectory contains the worktree-related
+ part of a linked checkout. This directory is ignored if
+ $GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/worktrees" will be
+ used instead.
+
SEE ALSO
--------
linkgit:git-init[1],
