Documentation / gitrepository-layout.txton commit do not write null sha1s to on-disk index (4337b58)
   1gitrepository-layout(5)
   2=======================
   3
   4NAME
   5----
   6gitrepository-layout - Git Repository Layout
   7
   8SYNOPSIS
   9--------
  10$GIT_DIR/*
  11
  12DESCRIPTION
  13-----------
  14
  15You may find these things in your git repository (`.git`
  16directory for a repository associated with your working tree, or
  17`<project>.git` directory for a public 'bare' repository. It is
  18also possible to have a working tree where `.git` is a plain
  19ASCII file containing `gitdir: <path>`, i.e. the path to the
  20real git repository).
  21
  22objects::
  23        Object store associated with this repository.  Usually
  24        an object store is self sufficient (i.e. all the objects
  25        that are referred to by an object found in it are also
  26        found in it), but there are a few ways to violate it.
  27+
  28. You could have an incomplete but locally usable repository
  29by creating a shallow clone.  See linkgit:git-clone[1].
  30. You could be using the `objects/info/alternates` or
  31`$GIT_ALTERNATE_OBJECT_DIRECTORIES` mechanisms to 'borrow'
  32objects from other object stores.  A repository with this kind
  33of incomplete object store is not suitable to be published for
  34use with dumb transports but otherwise is OK as long as
  35`objects/info/alternates` points at the object stores it
  36borrows from.
  37
  38objects/[0-9a-f][0-9a-f]::
  39        A newly created object is stored in its own file.
  40        The objects are splayed over 256 subdirectories using
  41        the first two characters of the sha1 object name to
  42        keep the number of directory entries in `objects`
  43        itself to a manageable number. Objects found
  44        here are often called 'unpacked' (or 'loose') objects.
  45
  46objects/pack::
  47        Packs (files that store many object in compressed form,
  48        along with index files to allow them to be randomly
  49        accessed) are found in this directory.
  50
  51objects/info::
  52        Additional information about the object store is
  53        recorded in this directory.
  54
  55objects/info/packs::
  56        This file is to help dumb transports discover what packs
  57        are available in this object store.  Whenever a pack is
  58        added or removed, `git update-server-info` should be run
  59        to keep this file up-to-date if the repository is
  60        published for dumb transports.  'git repack' does this
  61        by default.
  62
  63objects/info/alternates::
  64        This file records paths to alternate object stores that
  65        this object store borrows objects from, one pathname per
  66        line. Note that not only native Git tools use it locally,
  67        but the HTTP fetcher also tries to use it remotely; this
  68        will usually work if you have relative paths (relative
  69        to the object database, not to the repository!) in your
  70        alternates file, but it will not work if you use absolute
  71        paths unless the absolute path in filesystem and web URL
  72        is the same. See also 'objects/info/http-alternates'.
  73
  74objects/info/http-alternates::
  75        This file records URLs to alternate object stores that
  76        this object store borrows objects from, to be used when
  77        the repository is fetched over HTTP.
  78
  79refs::
  80        References are stored in subdirectories of this
  81        directory.  The 'git prune' command knows to preserve
  82        objects reachable from refs found in this directory and
  83        its subdirectories.
  84
  85refs/heads/`name`::
  86        records tip-of-the-tree commit objects of branch `name`
  87
  88refs/tags/`name`::
  89        records any object name (not necessarily a commit
  90        object, or a tag object that points at a commit object).
  91
  92refs/remotes/`name`::
  93        records tip-of-the-tree commit objects of branches copied
  94        from a remote repository.
  95
  96packed-refs::
  97        records the same information as refs/heads/, refs/tags/,
  98        and friends record in a more efficient way.  See
  99        linkgit:git-pack-refs[1].
 100
 101HEAD::
 102        A symref (see glossary) to the `refs/heads/` namespace
 103        describing the currently active branch.  It does not mean
 104        much if the repository is not associated with any working tree
 105        (i.e. a 'bare' repository), but a valid git repository
 106        *must* have the HEAD file; some porcelains may use it to
 107        guess the designated "default" branch of the repository
 108        (usually 'master').  It is legal if the named branch
 109        'name' does not (yet) exist.  In some legacy setups, it is
 110        a symbolic link instead of a symref that points at the current
 111        branch.
 112+
 113HEAD can also record a specific commit directly, instead of
 114being a symref to point at the current branch.  Such a state
 115is often called 'detached HEAD.'  See linkgit:git-checkout[1]
 116for details.
 117
 118branches::
 119        A slightly deprecated way to store shorthands to be used
 120        to specify a URL to 'git fetch', 'git pull' and 'git push'.
 121        A file can be stored as `branches/<name>` and then
 122        'name' can be given to these commands in place of
 123        'repository' argument.  See the REMOTES section in
 124        linkgit:git-fetch[1] for details.  This mechanism is legacy
 125        and not likely to be found in modern repositories.
 126
 127hooks::
 128        Hooks are customization scripts used by various git
 129        commands.  A handful of sample hooks are installed when
 130        'git init' is run, but all of them are disabled by
 131        default.  To enable, the `.sample` suffix has to be
 132        removed from the filename by renaming.
 133        Read linkgit:githooks[5] for more details about
 134        each hook.
 135
 136index::
 137        The current index file for the repository.  It is
 138        usually not found in a bare repository.
 139
 140info::
 141        Additional information about the repository is recorded
 142        in this directory.
 143
 144info/refs::
 145        This file helps dumb transports discover what refs are
 146        available in this repository.  If the repository is
 147        published for dumb transports, this file should be
 148        regenerated by 'git update-server-info' every time a tag
 149        or branch is created or modified.  This is normally done
 150        from the `hooks/update` hook, which is run by the
 151        'git-receive-pack' command when you 'git push' into the
 152        repository.
 153
 154info/grafts::
 155        This file records fake commit ancestry information, to
 156        pretend the set of parents a commit has is different
 157        from how the commit was actually created.  One record
 158        per line describes a commit and its fake parents by
 159        listing their 40-byte hexadecimal object names separated
 160        by a space and terminated by a newline.
 161
 162info/exclude::
 163        This file, by convention among Porcelains, stores the
 164        exclude pattern list. `.gitignore` is the per-directory
 165        ignore file.  'git status', 'git add', 'git rm' and
 166        'git clean' look at it but the core git commands do not look
 167        at it.  See also: linkgit:gitignore[5].
 168
 169remotes::
 170        Stores shorthands for URL and default refnames for use
 171        when interacting with remote repositories via 'git fetch',
 172        'git pull' and 'git push' commands.  See the REMOTES section
 173        in linkgit:git-fetch[1] for details.  This mechanism is legacy
 174        and not likely to be found in modern repositories.
 175
 176logs::
 177        Records of changes made to refs are stored in this
 178        directory.  See linkgit:git-update-ref[1]
 179        for more information.
 180
 181logs/refs/heads/`name`::
 182        Records all changes made to the branch tip named `name`.
 183
 184logs/refs/tags/`name`::
 185        Records all changes made to the tag named `name`.
 186
 187shallow::
 188        This is similar to `info/grafts` but is internally used
 189        and maintained by shallow clone mechanism.  See `--depth`
 190        option to linkgit:git-clone[1] and linkgit:git-fetch[1].
 191
 192SEE ALSO
 193--------
 194linkgit:git-init[1],
 195linkgit:git-clone[1],
 196linkgit:git-fetch[1],
 197linkgit:git-pack-refs[1],
 198linkgit:git-gc[1],
 199linkgit:git-checkout[1],
 200linkgit:gitglossary[7],
 201link:user-manual.html[The Git User's Manual]
 202
 203GIT
 204---
 205Part of the linkgit:git[1] suite.