read-cache: split-index mode
[git/git.git] / Documentation / gitrepository-layout.txt
1 gitrepository-layout(5)
2 =======================
3
4 NAME
5 ----
6 gitrepository-layout - Git Repository Layout
7
8 SYNOPSIS
9 --------
10 $GIT_DIR/*
11
12 DESCRIPTION
13 -----------
14
15 A Git repository comes in two different flavours:
16
17 * a `.git` directory at the root of the working tree;
18
19 * a `<project>.git` directory that is a 'bare' repository
20 (i.e. without its own working tree), that is typically used for
21 exchanging histories with others by pushing into it and fetching
22 from it.
23
24 *Note*: Also you can have a plain text file `.git` at the root of
25 your working tree, containing `gitdir: <path>` to point at the real
26 directory that has the repository. This mechanism is often used for
27 a working tree of a submodule checkout, to allow you in the
28 containing superproject to `git checkout` a branch that does not
29 have the submodule. The `checkout` has to remove the entire
30 submodule working tree, without losing the submodule repository.
31
32 These things may exist in a Git repository.
33
34 objects::
35 Object store associated with this repository. Usually
36 an object store is self sufficient (i.e. all the objects
37 that are referred to by an object found in it are also
38 found in it), but there are a few ways to violate it.
39 +
40 . You could have an incomplete but locally usable repository
41 by creating a shallow clone. See linkgit:git-clone[1].
42 . You could be using the `objects/info/alternates` or
43 `$GIT_ALTERNATE_OBJECT_DIRECTORIES` mechanisms to 'borrow'
44 objects from other object stores. A repository with this kind
45 of incomplete object store is not suitable to be published for
46 use with dumb transports but otherwise is OK as long as
47 `objects/info/alternates` points at the object stores it
48 borrows from.
49
50 objects/[0-9a-f][0-9a-f]::
51 A newly created object is stored in its own file.
52 The objects are splayed over 256 subdirectories using
53 the first two characters of the sha1 object name to
54 keep the number of directory entries in `objects`
55 itself to a manageable number. Objects found
56 here are often called 'unpacked' (or 'loose') objects.
57
58 objects/pack::
59 Packs (files that store many object in compressed form,
60 along with index files to allow them to be randomly
61 accessed) are found in this directory.
62
63 objects/info::
64 Additional information about the object store is
65 recorded in this directory.
66
67 objects/info/packs::
68 This file is to help dumb transports discover what packs
69 are available in this object store. Whenever a pack is
70 added or removed, `git update-server-info` should be run
71 to keep this file up-to-date if the repository is
72 published for dumb transports. 'git repack' does this
73 by default.
74
75 objects/info/alternates::
76 This file records paths to alternate object stores that
77 this object store borrows objects from, one pathname per
78 line. Note that not only native Git tools use it locally,
79 but the HTTP fetcher also tries to use it remotely; this
80 will usually work if you have relative paths (relative
81 to the object database, not to the repository!) in your
82 alternates file, but it will not work if you use absolute
83 paths unless the absolute path in filesystem and web URL
84 is the same. See also 'objects/info/http-alternates'.
85
86 objects/info/http-alternates::
87 This file records URLs to alternate object stores that
88 this object store borrows objects from, to be used when
89 the repository is fetched over HTTP.
90
91 refs::
92 References are stored in subdirectories of this
93 directory. The 'git prune' command knows to preserve
94 objects reachable from refs found in this directory and
95 its subdirectories.
96
97 refs/heads/`name`::
98 records tip-of-the-tree commit objects of branch `name`
99
100 refs/tags/`name`::
101 records any object name (not necessarily a commit
102 object, or a tag object that points at a commit object).
103
104 refs/remotes/`name`::
105 records tip-of-the-tree commit objects of branches copied
106 from a remote repository.
107
108 refs/replace/`<obj-sha1>`::
109 records the SHA-1 of the object that replaces `<obj-sha1>`.
110 This is similar to info/grafts and is internally used and
111 maintained by linkgit:git-replace[1]. Such refs can be exchanged
112 between repositories while grafts are not.
113
114 packed-refs::
115 records the same information as refs/heads/, refs/tags/,
116 and friends record in a more efficient way. See
117 linkgit:git-pack-refs[1].
118
119 HEAD::
120 A symref (see glossary) to the `refs/heads/` namespace
121 describing the currently active branch. It does not mean
122 much if the repository is not associated with any working tree
123 (i.e. a 'bare' repository), but a valid Git repository
124 *must* have the HEAD file; some porcelains may use it to
125 guess the designated "default" branch of the repository
126 (usually 'master'). It is legal if the named branch
127 'name' does not (yet) exist. In some legacy setups, it is
128 a symbolic link instead of a symref that points at the current
129 branch.
130 +
131 HEAD can also record a specific commit directly, instead of
132 being a symref to point at the current branch. Such a state
133 is often called 'detached HEAD.' See linkgit:git-checkout[1]
134 for details.
135
136 branches::
137 A slightly deprecated way to store shorthands to be used
138 to specify a URL to 'git fetch', 'git pull' and 'git push'.
139 A file can be stored as `branches/<name>` and then
140 'name' can be given to these commands in place of
141 'repository' argument. See the REMOTES section in
142 linkgit:git-fetch[1] for details. This mechanism is legacy
143 and not likely to be found in modern repositories.
144
145 hooks::
146 Hooks are customization scripts used by various Git
147 commands. A handful of sample hooks are installed when
148 'git init' is run, but all of them are disabled by
149 default. To enable, the `.sample` suffix has to be
150 removed from the filename by renaming.
151 Read linkgit:githooks[5] for more details about
152 each hook.
153
154 index::
155 The current index file for the repository. It is
156 usually not found in a bare repository.
157
158 sharedindex.<SHA-1>::
159 The shared index part, to be referenced by $GIT_DIR/index and
160 other temporary index files. Only valid in split index mode.
161
162 info::
163 Additional information about the repository is recorded
164 in this directory.
165
166 info/refs::
167 This file helps dumb transports discover what refs are
168 available in this repository. If the repository is
169 published for dumb transports, this file should be
170 regenerated by 'git update-server-info' every time a tag
171 or branch is created or modified. This is normally done
172 from the `hooks/update` hook, which is run by the
173 'git-receive-pack' command when you 'git push' into the
174 repository.
175
176 info/grafts::
177 This file records fake commit ancestry information, to
178 pretend the set of parents a commit has is different
179 from how the commit was actually created. One record
180 per line describes a commit and its fake parents by
181 listing their 40-byte hexadecimal object names separated
182 by a space and terminated by a newline.
183 +
184 Note that the grafts mechanism is outdated and can lead to problems
185 transferring objects between repositories; see linkgit:git-replace[1]
186 for a more flexible and robust system to do the same thing.
187
188 info/exclude::
189 This file, by convention among Porcelains, stores the
190 exclude pattern list. `.gitignore` is the per-directory
191 ignore file. 'git status', 'git add', 'git rm' and
192 'git clean' look at it but the core Git commands do not look
193 at it. See also: linkgit:gitignore[5].
194
195 info/sparse-checkout::
196 This file stores sparse checkout patterns.
197 See also: linkgit:git-read-tree[1].
198
199 remotes::
200 Stores shorthands for URL and default refnames for use
201 when interacting with remote repositories via 'git fetch',
202 'git pull' and 'git push' commands. See the REMOTES section
203 in linkgit:git-fetch[1] for details. This mechanism is legacy
204 and not likely to be found in modern repositories.
205
206 logs::
207 Records of changes made to refs are stored in this
208 directory. See linkgit:git-update-ref[1]
209 for more information.
210
211 logs/refs/heads/`name`::
212 Records all changes made to the branch tip named `name`.
213
214 logs/refs/tags/`name`::
215 Records all changes made to the tag named `name`.
216
217 shallow::
218 This is similar to `info/grafts` but is internally used
219 and maintained by shallow clone mechanism. See `--depth`
220 option to linkgit:git-clone[1] and linkgit:git-fetch[1].
221
222 modules::
223 Contains the git-repositories of the submodules.
224
225 SEE ALSO
226 --------
227 linkgit:git-init[1],
228 linkgit:git-clone[1],
229 linkgit:git-fetch[1],
230 linkgit:git-pack-refs[1],
231 linkgit:git-gc[1],
232 linkgit:git-checkout[1],
233 linkgit:gitglossary[7],
234 link:user-manual.html[The Git User's Manual]
235
236 GIT
237 ---
238 Part of the linkgit:git[1] suite.