gitrepository-layout

GITREPOSITORY-LAYOU(5)            Git Manual            GITREPOSITORY-LAYOU(5)



NAME
       gitrepository-layout - Git Repository Layout

SYNOPSIS
       $GIT_DIR/*

DESCRIPTION
       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 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 object 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 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
           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:

       ·   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 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).

       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:

       noop
           This extension does not change git’s behavior at all. It is useful
           only for testing format-1 compatibility.

       preciousObjects
           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).

       partialclone
           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.

       worktreeConfig
           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_COMMON_DIR/worktrees/<id>/config.worktree)

SEE ALSO
       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[1]

GIT
       Part of the git(1) suite

NOTES
        1. The Git User’s Manual
           file:///usr/share/doc/git-doc/user-manual.html



Git 2.23.0                        08/17/2019            GITREPOSITORY-LAYOU(5)