git/Documentation/repository-layout.txt

git repository layout
=====================

You may find these things in your git repository (`.git`
directory for a repository associated with your working tree, or
`'project'.git` directory for a public 'bare' 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 couple of ways to violate
	it.
+
. You could populate the repository by running a commit walker
without `-a` option.  Depending on which options are given, you
could have only commit objects without associated blobs and
trees this way, for example.  A repository with this kind of
incomplete object store is not suitable to be published to the
outside world but sometimes useful for private repository.
. You also could have an incomplete but locally usable repository
by cloning shallowly.  See gitlink:git-clone[1].
. You can be using `objects/info/alternates` mechanism, or
`$GIT_ALTERNATE_OBJECT_DIRECTORIES` mechanism 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 right object stores
it borrows from.

objects/[0-9a-f][0-9a-f]::
	Traditionally, each object is stored in its own file.
	They are split into 256 subdirectories using the first
	two letters from its object name to keep the number of
	directory entries `objects` directory itself needs to
	hold.  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 keep
	objects reachable from refs found in this directory and
	its subdirectories.

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.

packed-refs::
	records the same information as refs/heads/, refs/tags/,
	and friends record in a more efficient way.  See
	gitlink:git-pack-refs[1].

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', and almost all commands work
identically as normal.  See gitlink:git-checkout[1] for
details.

branches::
	A slightly deprecated way to store shorthands to be used
	to specify URL to `git fetch`, `git pull` and `git push`
	commands is to store a file in `branches/'name'` and
	give 'name' to these commands in place of 'repository'
	argument.

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, they need to be made executable.
	Read link:hooks.html[hooks] for more details about
	each hook.

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

info::
	Additional information about the repository is recorded
	in this directory.

info/refs::
	This file is to help dumb transports to discover what
	refs are available in this repository.  Whenever you
	create/delete a new branch or a new tag, `git
	update-server-info` should be run to keep this file
	up-to-date if the repository is published for dumb
	transports.  The `git-receive-pack` command, which is
	run on a remote repository when you `git push` into it,
	runs `hooks/update` hook to help you achieve this.

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.

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: gitlink:git-ls-files[1] `--exclude-from`
	and `--exclude-per-directory`.

remotes::
	Stores shorthands to be used to give URL and default
	refnames to interact with remote repository to `git
	fetch`, `git pull` and `git push` commands.

logs::
	Records of changes made to refs are stored in this
	directory.  See the documentation on git-update-ref
	for more information.

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 gitlink:git-clone[1] and gitlink:git-fetch[1].