SYNOPSIS
--------
+[verse]
'git read-tree' [[-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>]
[-u [--exclude-per-directory=<gitignore>] | -i]]
[--index-output=<file>] [--no-sparse-checkout]
- <tree-ish1> [<tree-ish2> [<tree-ish3>]]
+ (--empty | <tree-ish1> [<tree-ish2> [<tree-ish3>]])
DESCRIPTION
-i::
Usually a merge requires the index file as well as the
- files in the working tree are up to date with the
+ files in the working tree to be up to date with the
current head commit, in order not to lose local
changes. This flag disables the check with the working
tree and is meant to be used when creating a merge of
trees that are not directly related to the current
working tree status into a temporary index file.
+-n::
+--dry-run::
+ Check if the command would error out, without updating the index
+ nor the files in the working tree for real.
+
-v::
Show the progress of checking files out.
--aggressive::
Usually a three-way merge by 'git read-tree' resolves
the merge for really trivial cases and leaves other
- cases unresolved in the index, so that Porcelains can
+ cases unresolved in the index, so that porcelains can
implement different merge policies. This flag makes the
- command to resolve a few more cases internally:
+ command resolve a few more cases internally:
+
* when one side removes a path and the other side leaves the path
unmodified. The resolution is to remove that path.
* when both sides remove a path. The resolution is to remove that path.
-* when both sides adds a path identically. The resolution
+* when both sides add a path identically. The resolution
is to add that path.
--prefix=<prefix>/::
Keep the current index contents, and read the contents
- of named tree-ish under directory at `<prefix>`. The
+ of the named tree-ish under the directory at `<prefix>`. The
original index file cannot have anything at the path
- `<prefix>` itself,
and have nothing in `<prefix>/`
+ `<prefix>` itself,
nor anything in the `<prefix>/`
directory. Note that the `<prefix>/` value must end
with a slash.
Disable sparse checkout support even if `core.sparseCheckout`
is true.
+--empty::
+ Instead of reading tree object(s) into the index, just empty
+ it.
+
<tree-ish#>::
The id of the tree object(s) to be read/merged.
~~~~~~~~~~~~~~~~~
If only 1 tree is specified, 'git read-tree' operates as if the user did not
specify `-m`, except that if the original index has an entry for a
-given pathname, and the contents of the path matches with the tree
+given pathname, and the contents of the path match with the tree
being read, the stat info from the index is used. (In other words, the
index's stat()s take precedence over the merged tree's).
the following:
1. The current index and work tree is derived from $H, but
- the user may have local changes in them since $H;
+ the user may have local changes in them since $H.
2. The user wants to fast-forward to $M.
In this case, the `git read-tree -m $H $M` command makes sure
that no local change is lost as the result of this "merge".
-Here are the "carry forward" rules:
+Here are the "carry forward" rules, where "I" denotes the index,
+"clean" means that index and work tree coincide, and "exists"/"nothing"
+refer to the presence of a path in the specified commit:
- I (index) H M Result
+ I H M Result
-------------------------------------------------------
- 0 nothing nothing nothing (does not happen)
- 1 nothing nothing exists use M
- 2 nothing exists nothing remove path from index
- 3 nothing exists exists, use M if "initial checkout"
+ 0 nothing nothing nothing (does not happen)
+ 1 nothing nothing exists use M
+ 2 nothing exists nothing remove path from index
+ 3 nothing exists exists, use M if "initial checkout",
H == M keep index otherwise
- exists fail
+ exists, fail
H != M
clean I==H I==M
------------------
- 4 yes N/A N/A nothing nothing keep index
- 5 no N/A N/A nothing nothing keep index
+ 4 yes N/A N/A nothing nothing keep index
+ 5 no N/A N/A nothing nothing keep index
- 6 yes N/A yes nothing exists keep index
- 7 no N/A yes nothing exists keep index
- 8 yes N/A no nothing exists fail
- 9 no N/A no nothing exists fail
+ 6 yes N/A yes nothing exists keep index
+ 7 no N/A yes nothing exists keep index
+ 8 yes N/A no nothing exists fail
+ 9 no N/A no nothing exists fail
10 yes yes N/A exists nothing remove path from index
11 no yes N/A exists nothing fail
12 yes no N/A exists nothing fail
13 no no N/A exists nothing fail
- clean (H=M)
+ clean (H==M)
------
14 yes exists exists keep index
15 no exists exists keep index
21 no yes no exists exists fail
In all "keep index" cases, the index entry stays as in the
-original index file. If the entry were not up to date,
+original index file. If the entry is not up to date,
'git read-tree' keeps the copy in the work tree intact when
operating under the -u flag.
When this form of 'git read-tree' returns successfully, you can
-see what "local changes" you made are carried forward by running
+see which of the "local changes" that you made were carried forward by running
`git diff-index --cached $M`. Note that this does not
-necessarily match `git diff-index --cached $H` would have
+necessarily match what `git diff-index --cached $H` would have
produced before such a two tree merge. This is because of cases
18 and 19 --- if you already had the changes in $M (e.g. maybe
you picked it up via e-mail in a patch form), `git diff-index
--cached $H` would have told you about the change before this
merge, but it would not show in `git diff-index --cached $M`
-output after two-tree merge.
+output after the two-tree merge.
-Case #3 is slightly tricky and needs explanation. The result from this
+Case 3 is slightly tricky and needs explanation. The result from this
rule logically should be to remove the path if the user staged the removal
of the path and then switching to a new branch. That however will prevent
the initial checkout from happening, so the rule is modified to use M (new
-tree) only when the contents of the index is empty. Otherwise the removal
+tree) only when the content of the index is empty. Otherwise the removal
of the path is kept as long as $H and $M are the same.
3-Way Merge
Sparse checkout
---------------
-"Sparse checkout" allows to sparsely populate working directory.
-It uses skip-worktree bit (see linkgit:git-update-index[1]) to tell
-Git whether a file on working directory is worth looking at.
+"Sparse checkout" allows populating the working directory sparsely.
+It uses the skip-worktree bit (see linkgit:git-update-index[1]) to tell
+Git whether a file in the working directory is worth looking at.
-"git read-tree" and other merge-based commands ("git merge", "git
-checkout"...) can help maintaining skip-worktree bitmap and working
+'git read-tree' and other merge-based commands ('git merge', 'git
+checkout'...) can help maintaining the skip-worktree bitmap and working
directory update. `$GIT_DIR/info/sparse-checkout` is used to
-define the skip-worktree reference bitmap. When "git read-tree" needs
-to update working directory, it will reset skip-worktree bit in index
+define the skip-worktree reference bitmap. When 'git read-tree' needs
+to update the working directory, it resets the skip-worktree bit in the index
based on this file, which uses the same syntax as .gitignore files.
-If an entry matches a pattern in this file, skip-worktree will be
-set on that entry. Otherwise, skip-worktree will be unset.
+If an entry matches a pattern in this file, skip-worktree will not be
+set on that entry. Otherwise, skip-worktree will be set.
Then it compares the new skip-worktree value with the previous one. If
-skip-worktree turns from unset to set, it will add the corresponding
-file back. If it turns from set to unset, that file will be removed.
+skip-worktree turns from set to unset, it will add the corresponding
+file back. If it turns from unset to set, that file will be removed.
While `$GIT_DIR/info/sparse-checkout` is usually used to specify what
-files are in. You can also specify what files are _not_ in, using
-negate patterns. For example, to remove file "unwanted":
+files are in, you can also specify what files are _not_ in, using
+negate patterns. For example, to remove the file `unwanted`:
----------------
-*
+/*
!unwanted
----------------
-Another tricky thing is fully repopulating working directory when you
+Another tricky thing is fully repopulating the working directory when you
no longer want sparse checkout. You cannot just disable "sparse
-checkout" because skip-worktree are still in the index and you working
-directory is still sparsely populated. You should re-populate working
+checkout" because skip-worktree bits are still in the index and your working
+directory is still sparsely populated. You should re-populate the working
directory with the `$GIT_DIR/info/sparse-checkout` file content as
follows:
----------------
-*
+/*
----------------
-Then you can disable sparse checkout. Sparse checkout support in "git
-read-tree" and similar commands is disabled by default. You need to
+Then you can disable sparse checkout. Sparse checkout support in 'git
+read-tree' and similar commands is disabled by default. You need to
turn `core.sparseCheckout` on in order to have sparse checkout
support.
linkgit:git-write-tree[1]; linkgit:git-ls-files[1];
linkgit:gitignore[5]
-
-Author
-------
-Written by Linus Torvalds <torvalds@osdl.org>
-
-Documentation
---------------
-Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
-
GIT
---
Part of the linkgit:git[1] suite