GITREPOSITORY-LAYOU(5) Git Manual GITREPOSITORY-LAYOU(5)
gitrepository-layout - Git Repository Layout
A Git repository comes in two different flavours:
o a .git directory at the root of the working tree;
o a <project>.git directory that is a bare repository (i.e. without
its own working tree), that is typically used for exchanging
histories with others by pushing into it and fetching from it.
Note: Also you can have a plain text file .git at the root of your
working tree, containing gitdir: <path> to point at the real directory
that has the repository. This mechanism is often used for a working
tree of a submodule checkout, to allow you in the containing
superproject to git checkout a branch that does not have the submodule.
The checkout has to remove the entire submodule working tree, without
losing the submodule repository.
These things may exist in a Git repository.
Object store associated with this repository. Usually an object
store is self sufficient (i.e. all the objects that are referred to
by an object found in it are also found in it), but there are a few
ways to violate it.
1. You could have an incomplete but locally usable repository by
creating a shallow clone. See git-clone(1).
2. You could be using the objects/info/alternates or
$GIT_ALTERNATE_OBJECT_DIRECTORIES mechanisms to borrow objects
from other object stores. A repository with this kind of
incomplete object store is not suitable to be published for use
with dumb transports but otherwise is OK as long as
objects/info/alternates points at the object stores it borrows
This directory is ignored if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/objects" will be used instead.
A newly created object is stored in its own file. The objects are
splayed over 256 subdirectories using the first two characters of
the sha1 object name to keep the number of directory entries in
objects itself to a manageable number. Objects found here are often
called unpacked (or loose) objects.
Packs (files that store many objects in compressed form, along with
index files to allow them to be randomly accessed) are found in
Additional information about the object store is recorded in this
This file is to help dumb transports discover what packs are
available in this object store. Whenever a pack is added or
removed, git update-server-info should be run to keep this file up
to date if the repository is published for dumb transports. git
repack does this by default.
This file records paths to alternate object stores that this object
store borrows objects from, one pathname per line. Note that not
only native Git tools use it locally, but the HTTP fetcher also
tries to use it remotely; this will usually work if you have
relative paths (relative to the object database, not to the
repository!) in your alternates file, but it will not work if you
use absolute paths unless the absolute path in filesystem and web
URL is the same. See also objects/info/http-alternates.
This file records URLs to alternate object stores that this object
store borrows objects from, to be used when the repository is
fetched over HTTP.
References are stored in subdirectories of this directory. The git
prune command knows to preserve objects reachable from refs found
in this directory and its subdirectories. This directory is ignored
(except refs/bisect, refs/rewritten and refs/worktree) if
$GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/refs" will be used
records tip-of-the-tree commit objects of branch name
records any object name (not necessarily a commit object, or a tag
object that points at a commit object).
records tip-of-the-tree commit objects of branches copied from a
records the SHA-1 of the object that replaces <obj-sha1>. This is
similar to info/grafts and is internally used and maintained by
git-replace(1). Such refs can be exchanged between repositories
while grafts are not.
records the same information as refs/heads/, refs/tags/, and
friends record in a more efficient way. See git-pack-refs(1). This
file is ignored if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/packed-refs" will be used instead.
A symref (see glossary) to the refs/heads/ namespace describing the
currently active branch. It does not mean much if the repository is
not associated with any working tree (i.e. a bare repository), but
a valid Git repository must have the HEAD file; some porcelains may
use it to guess the designated "default" branch of the repository
(usually master). It is legal if the named branch name does not
(yet) exist. In some legacy setups, it is a symbolic link instead
of a symref that points at the current branch.
HEAD can also record a specific commit directly, instead of being a
symref to point at the current branch. Such a state is often called
detached HEAD. See git-checkout(1) for details.
Repository specific configuration file. This file is ignored if
$GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/config" will be used
Working directory specific configuration file for the main working
directory in multiple working directory setup (see git-
A slightly deprecated way to store shorthands to be used to specify
a URL to git fetch, git pull and git push. A file can be stored as
branches/<name> and then name can be given to these commands in
place of repository argument. See the REMOTES section in git-
fetch(1) for details. This mechanism is legacy and not likely to be
found in modern repositories. This directory is ignored if
$GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/branches" will be used
Hooks are customization scripts used by various Git commands. A
handful of sample hooks are installed when git init is run, but all
of them are disabled by default. To enable, the .sample suffix has
to be removed from the filename by renaming. Read githooks(5) for
more details about each hook. This directory is ignored if
$GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/hooks" will be used
When multiple working trees are used, most of files in $GIT_DIR are
per-worktree with a few known exceptions. All files under common
however will be shared between all working trees.
The current index file for the repository. It is usually not found
in a bare repository.
The shared index part, to be referenced by $GIT_DIR/index and other
temporary index files. Only valid in split index mode.
Additional information about the repository is recorded in this
directory. This directory is ignored if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/info" will be used instead.
This file helps dumb transports discover what refs are available in
this repository. If the repository is published for dumb
transports, this file should be regenerated by git
update-server-info every time a tag or branch is created or
modified. This is normally done from the hooks/update hook, which
is run by the git-receive-pack command when you git push into the
This file records fake commit ancestry information, to pretend the
set of parents a commit has is different from how the commit was
actually created. One record per line describes a commit and its
fake parents by listing their 40-byte hexadecimal object names
separated by a space and terminated by a newline.
Note that the grafts mechanism is outdated and can lead to problems
transferring objects between repositories; see git-replace(1) for a
more flexible and robust system to do the same thing.
This file, by convention among Porcelains, stores the exclude
pattern list. .gitignore is the per-directory ignore file. git
status, git add, git rm and git clean look at it but the core Git
commands do not look at it. See also: gitignore(5).
Defines which attributes to assign to a path, similar to
per-directory .gitattributes files. See also: gitattributes(5).
This file stores sparse checkout patterns. See also: git-read-
Stores shorthands for URL and default refnames for use when
interacting with remote repositories via git fetch, git pull and
git push commands. See the REMOTES section in git-fetch(1) for
details. This mechanism is legacy and not likely to be found in
modern repositories. This directory is ignored if $GIT_COMMON_DIR
is set and "$GIT_COMMON_DIR/remotes" will be used instead.
Records of changes made to refs are stored in this directory. See
git-update-ref(1) for more information. This directory is ignored
(except logs/HEAD) if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/logs" will be used instead.
Records all changes made to the branch tip named name.
Records all changes made to the tag named name.
This is similar to info/grafts but is internally used and
maintained by shallow clone mechanism. See --depth option to git-
clone(1) and git-fetch(1). This file is ignored if $GIT_COMMON_DIR
is set and "$GIT_COMMON_DIR/shallow" will be used instead.
If this file exists, $GIT_COMMON_DIR (see git(1)) will be set to
the path specified in this file if it is not explicitly set. If the
specified path is relative, it is relative to $GIT_DIR. The
repository with commondir is incomplete without the repository
pointed by "commondir".
Contains the git-repositories of the submodules.
Contains administrative data for linked working trees. Each
subdirectory contains the working tree-related part of a linked
working tree. This directory is ignored if $GIT_COMMON_DIR is set,
in which case "$GIT_COMMON_DIR/worktrees" will be used instead.
A text file containing the absolute path back to the .git file that
points to here. This is used to check if the linked repository has
been manually removed and there is no need to keep this directory
any more. The mtime of this file should be updated every time the
linked repository is accessed.
If this file exists, the linked working tree may be on a portable
device and not available. The presence of this file prevents
worktrees/<id> from being pruned either automatically or manually
by git worktree prune. The file may contain a string explaining why
the repository is locked.
Working directory specific configuration file.
GIT REPOSITORY FORMAT VERSIONS
Every git repository is marked with a numeric version in the
core.repositoryformatversion key of its config file. This version
specifies the rules for operating on the on-disk repository data. An
implementation of git which does not understand a particular version
advertised by an on-disk repository MUST NOT operate on that
repository; doing so risks not only producing wrong results, but
actually losing data.
Because of this rule, version bumps should be kept to an absolute
minimum. Instead, we generally prefer these strategies:
o bumping format version numbers of individual data files (e.g.,
index, packfiles, etc). This restricts the incompatibilities only
to those files.
o introducing new data that gracefully degrades when used by older
clients (e.g., pack bitmap files are ignored by older clients,
which simply do not take advantage of the optimization they
A whole-repository format version bump should only be part of a change
that cannot be independently versioned. For instance, if one were to
change the reachability rules for objects, or the rules for locking
refs, that would require a bump of the repository format version.
Note that this applies only to accessing the repository's disk contents
directly. An older client which understands only format 0 may still
connect via git:// to a repository using format 1, as long as the
server process understands format 1.
The preferred strategy for rolling out a version bump (whether whole
repository or for a single file) is to teach git to read the new
format, and allow writing the new format with a config switch or
command line option (for experimentation or for those who do not care
about backwards compatibility with older gits). Then after a long
period to allow the reading capability to become common, we may switch
to writing the new format by default.
The currently defined format versions are:
This is the format defined by the initial version of git, including but
not limited to the format of the repository directory, the repository
configuration file, and the object and ref storage. Specifying the
complete behavior of git is beyond the scope of this document.
This format is identical to version 0, with the following exceptions:
1. When reading the core.repositoryformatversion variable, a git
implementation which supports version 1 MUST also read any
configuration keys found in the extensions section of the
2. If a version-1 repository specifies any extensions.* keys that the
running git has not implemented, the operation MUST NOT proceed.
Similarly, if the value of any known key is not understood by the
implementation, the operation MUST NOT proceed.
Note that if no extensions are specified in the config file, then
core.repositoryformatversion SHOULD be set to 0 (setting it to 1
provides no benefit, and makes the repository incompatible with older
implementations of git).
This document will serve as the master list for extensions. Any
implementation wishing to define a new extension should make a note of
it here, in order to claim the name.
The defined extensions are:
This extension does not change git's behavior at all. It is useful
only for testing format-1 compatibility.
When the config key extensions.preciousObjects is set to true,
objects in the repository MUST NOT be deleted (e.g., by git-prune
or git repack -d).
When the config key extensions.partialclone is set, it indicates
that the repo was created with a partial clone (or later performed
a partial fetch) and that the remote may have omitted sending
certain unwanted objects. Such a remote is called a "promisor
remote" and it promises that all such omitted objects can be
fetched from it in the future.
The value of this key is the name of the promisor remote.
If set, by default "git config" reads from both "config" and
"config.worktree" file from GIT_DIR in that order. In multiple
working directory mode, "config" file is shared while
"config.worktree" is per-working directory (i.e., it's in
git-init(1), git-clone(1), git-fetch(1), git-pack-refs(1), git-gc(1),
git-checkout(1), gitglossary(7), The Git User's Manual
Part of the git(1) suite
1. The Git User's Manual
Git 2.25.1 04/26/2023 GITREPOSITORY-LAYOU(5)
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