Documentation / repository-layout.txton commit setup_git_directory: make sure GIT_DIR is a valid repository. (5e7bfe2)
   1git repository layout
   2=====================
   3
   4You may find these things in your git repository (`.git`
   5directory for a repository associated with your working tree, or
   6`'project'.git` directory for a public 'naked' repository).
   7
   8objects::
   9        Object store associated with this repository.  Usually
  10        an object store is self sufficient (i.e. all the objects
  11        that are referred to by an object found in it are also
  12        found in it), but there are couple of ways to violate
  13        it.
  14+
  15. You could populate the repository by running a commit walker
  16without `-a` option.  Depending on which options are given, you
  17could have only commit objects without associated blobs and
  18trees this way, for example.  A repository with this kind of
  19incomplete object store is not suitable to be published to the
  20outside world but sometimes useful for private repository.
  21. You can be using `objects/info/alternates` mechanism, or
  22`$GIT_ALTERNATE_OBJECT_DIRECTORIES` mechanism to 'borrow'
  23objects from other object stores.  A repository with this kind
  24of incompete object store is not suitable to be published for
  25use with dumb transports but otherwise is OK as long as
  26`objects/info/alternates` points at the right object stores
  27it borrows from.
  28
  29objects/[0-9a-f][0-9a-f]::
  30        Traditionally, each object is stored in its own file.
  31        They are split into 256 subdirectories using the first
  32        two letters from its object name to keep the number of
  33        directory entries `objects` directory itself needs to
  34        hold.  Objects found here are often called 'unpacked'
  35        objects.
  36
  37objects/pack::
  38        Packs (files that store many object in compressed form,
  39        along with index files to allow them to be randomly
  40        accessed) are found in this directory.
  41
  42objects/info::
  43        Additional information about the object store is
  44        recorded in this directory.
  45
  46objects/info/packs::
  47        This file is to help dumb transports discover what packs
  48        are available in this object store.  Whenever a pack is
  49        added or removed, `git update-server-info` should be run
  50        to keep this file up-to-date if the repository is
  51        published for dumb transports.  `git repack` does this
  52        by default.
  53
  54objects/info/alternates::
  55        This file records absolute filesystem paths of alternate
  56        object stores that this object store borrows objects
  57        from, one pathname per line.
  58
  59refs::
  60        References are stored in subdirectories of this
  61        directory.  The `git prune` command knows to keep
  62        objects reachable from refs found in this directory and
  63        its subdirectories.
  64
  65refs/heads/`name`::
  66        records tip-of-the-tree commit objects of branch `name`
  67
  68refs/tags/`name`::
  69        records any object name (not necessarily a commit
  70        object, or a tag object that points at a commit object).
  71
  72HEAD::
  73        A symlink of the form `refs/heads/'name'` to point at
  74        the current branch, if exists.  It does not mean much if
  75        the repository is not associated with any working tree
  76        (i.e. 'naked' repository), but a valid git repository
  77        *must* have such a symlink here.  It is legal if the
  78        named branch 'name' does not (yet) exist.
  79
  80branches::
  81        A slightly deprecated way to store shorthands to be used
  82        to specify URL to `git fetch`, `git pull` and `git push`
  83        commands is to store a file in `branches/'name'` and
  84        give 'name' to these commands in place of 'repository'
  85        argument.
  86
  87hooks::
  88        Hooks are customization scripts used by various git
  89        commands.  A handful of sample hooks are installed when
  90        `git init-db` is run, but all of them are disabled by
  91        default.  To enable, they need to be made executable.
  92
  93index::
  94        The current index file for the repository.  It is
  95        usually not found in a naked repository.
  96
  97info::
  98        Additional information about the repository is recorded
  99        in this directory.
 100
 101info/refs::
 102        This file is to help dumb transports to discover what
 103        refs are available in this repository.  Whenever you
 104        create/delete a new branch or a new tag, `git
 105        update-server-info` should be run to keep this file
 106        up-to-date if the repository is published for dumb
 107        transports.  The `git-receive-pack` command, which is
 108        run on a remote repository when you `git push` into it,
 109        runs `hooks/update` hook to help you achive this.
 110
 111info/grafts::
 112        This file records fake commit ancestry information, to
 113        pretend the set of parents a commit has is different
 114        from how the commit was actually created.  One record
 115        per line describes a commit and its fake parents by
 116        listing their 40-byte hexadecimal object names separated
 117        by a space and terminated by a newline.
 118
 119info/exclude::
 120        This file, by convention among Porcelains, stores the
 121        exclude pattern list.  `git status` looks at it, but
 122        otherwise it is not looked at by any of the core git
 123        commands.
 124
 125remotes::
 126        Stores shorthands to be used to give URL and default
 127        refnames to interact with remote repository to `git
 128        fetch`, `git pull` and `git push` commands.