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 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'
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 absolute filesystem paths of alternate
object stores that this object store borrows objects
from, one pathname per line.

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).

HEAD::
A symlink of the form `refs/heads/'name'` to point at
the current branch, if exists. 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 such a symlink here. It is legal if the
named branch 'name' does not (yet) exist.

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-db` is run, but all of them are disabled by
default. To enable, they need to be made executable.

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. `git status` looks at it, but
otherwise it is not looked at by any of the core git
commands.

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.