GITREPOSITORY-LAYOUT(5) Git Manual GITREPOSITORY-LAYOUT(5)

NAME

gitrepository-layout - Git Repository Layout

SYNOPSIS

$GIT_DIR/*

DESCRIPTION

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 called a gitfile
and is usually managed via the git submodule and git worktree
commands. It 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.

objects
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 from.

This directory is ignored if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/objects" will be used instead.

objects/[0-9a-f][0-9a-f]
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.

objects/pack
Packs (files that store many objects in compressed form, along
with index files to allow them to be randomly accessed) are found
in this directory.

objects/info
Additional information about the object store is recorded in this
directory.

objects/info/packs
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.

objects/info/alternates
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.

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.

refs
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
instead.

refs/heads/name
records tip-of-the-tree commit objects of branch name

refs/tags/name
records any object name (not necessarily a commit object, or a
tag object that points at a commit object).

refs/remotes/name
records tip-of-the-tree commit objects of branches copied from a
remote repository.

refs/replace/<obj-sha1>
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.

packed-refs
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.

HEAD
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.

config
Repository specific configuration file. This file is ignored if
$GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/config" will be used
instead.

config.worktree
Working directory specific configuration file for the main
working directory in multiple working directory setup (see git-
worktree(1)).

branches
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 instead.

hooks
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 instead.

common
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.

index
The current index file for the repository. It is usually not
found in a bare repository.

sharedindex.<SHA-1>
The shared index part, to be referenced by $GIT_DIR/index and
other temporary index files. Only valid in split index mode.

info
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.

info/refs
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
repository.

info/grafts
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.

info/exclude
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).

info/attributes
Defines which attributes to assign to a path, similar to
per-directory .gitattributes files. See also: gitattributes(5).

info/sparse-checkout
This file stores sparse checkout patterns. See also: git-read-
tree(1).

remotes
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.

logs
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.

logs/refs/heads/name
Records all changes made to the branch tip named name.

logs/refs/tags/name
Records all changes made to the tag named name.

shallow
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.

commondir
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".

modules
Contains the git-repositories of the submodules.

worktrees
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.

worktrees/<id>/gitdir
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.

worktrees/<id>/locked
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.

worktrees/<id>/config.worktree
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
provide).

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:

Version 0
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.

Version 1
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
configuration file.

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).

The defined extensions are given in the extensions.* section of git-
config(1). Any implementation wishing to define a new extension
should make a note of it there, in order to claim the name.

SEE ALSO

git-init(1), git-clone(1), git-config(1), git-fetch(1), git-pack-
refs(1), git-gc(1), git-checkout(1), gitglossary(7), The Git User's
Manual[1]

GIT

Part of the git(1) suite

NOTES

1. The Git User's Manual
git-htmldocs/user-manual.html

Git 2.48.1 2025-01-13 GITREPOSITORY-LAYOUT(5)