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].