gitrepository-layout(5) — Linux manual page



NAME         top

       gitrepository-layout - Git Repository Layout

SYNOPSIS         top


DESCRIPTION         top

       A Git repository comes in two different flavours:

       •   a .git directory at the root of the working tree;

       •   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.

           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.

           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)

           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.

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

           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

           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 instead.

           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 remote repository.

           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

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

           Working directory specific configuration file for the main
           working directory in multiple working directory setup (see

           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 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.

           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

           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 repository.

           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:

           This file stores sparse checkout patterns. See also:

           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.


       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:

       •   bumping format version numbers of individual data files
           (e.g., index, packfiles, etc). This restricts the
           incompatibilities only to those files.

       •   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

       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

        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

       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" files 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_COMMON_DIR/worktrees/<id>/config.worktree)


           Specifies the file format for the ref database. The valid
           values are files (loose references with a packed-refs file)
           and reftable (see Documentation/technical/reftable.txt).

SEE ALSO         top

       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

GIT         top

       Part of the git(1) suite

NOTES         top

        1. The Git User’s Manual

COLOPHON         top

       This page is part of the git (Git distributed version control
       system) project.  Information about the project can be found at
       ⟨⟩.  If you have a bug report for this manual
       page, see ⟨⟩.  This page was obtained
       from the project's upstream Git repository
       ⟨⟩ on 2024-06-14.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2024-06-12.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Git         2024-06-12        GITREPOSITORY-LAYOUT(5)

Pages that refer to this page: git(1)git-config(1)git-gc(1)git-help(1)git-repack(1)git-show-ref(1)git-update-server-info(1)git-worktree(1)gitignore(5)gitcore-tutorial(7)gitglossary(7)