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![Nguyễn Thái Ngọc Duy](/assets/img/avatar_default.png)
This split-index mode is designed to keep write cost proportional to the number of changes the user has made, not the size of the work tree. (Read cost is another matter, to be dealt separately.) This mode stores index info in a pair of $GIT_DIR/index and $GIT_DIR/sharedindex.<SHA-1>. sharedindex is large and unchanged over time while "index" is smaller and updated often. Format details are in index-format.txt, although not everything is implemented in this patch. Shared indexes are not automatically removed, because it's unclear if the shared index is needed by any (even temporary) indexes by just looking at it. After a while you'll collect stale shared indexes. The good news is one shared index is useable for long, until $GIT_DIR/index becomes too big and sluggish that the new shared index must be created. The safest way to clean shared indexes is to turn off split index mode, so shared files are all garbage, delete them all, then turn on split index mode again. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
239 lines
8.3 KiB
Plaintext
239 lines
8.3 KiB
Plaintext
gitrepository-layout(5)
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=======================
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NAME
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----
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gitrepository-layout - Git Repository Layout
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SYNOPSIS
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--------
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$GIT_DIR/*
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DESCRIPTION
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-----------
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A Git repository comes in two different flavours:
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* a `.git` directory at the root of the working tree;
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* a `<project>.git` directory that is a 'bare' repository
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(i.e. without its own working tree), that is typically used for
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exchanging histories with others by pushing into it and fetching
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from it.
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*Note*: Also you can have a plain text file `.git` at the root of
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your working tree, containing `gitdir: <path>` to point at the real
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directory that has the repository. This mechanism is often used for
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a working tree of a submodule checkout, to allow you in the
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containing superproject to `git checkout` a branch that does not
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have the submodule. The `checkout` has to remove the entire
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submodule working tree, without losing the submodule repository.
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These things may exist in a Git repository.
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objects::
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Object store associated with this repository. Usually
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an object store is self sufficient (i.e. all the objects
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that are referred to by an object found in it are also
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found in it), but there are a few ways to violate it.
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+
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. You could have an incomplete but locally usable repository
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by creating a shallow clone. See linkgit:git-clone[1].
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. You could be using the `objects/info/alternates` or
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`$GIT_ALTERNATE_OBJECT_DIRECTORIES` mechanisms to 'borrow'
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objects from other object stores. A repository with this kind
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of incomplete object store is not suitable to be published for
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use with dumb transports but otherwise is OK as long as
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`objects/info/alternates` points at the object stores it
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borrows from.
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objects/[0-9a-f][0-9a-f]::
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A newly created object is stored in its own file.
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The objects are splayed over 256 subdirectories using
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the first two characters of the sha1 object name to
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keep the number of directory entries in `objects`
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itself to a manageable number. Objects found
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here are often called 'unpacked' (or 'loose') objects.
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objects/pack::
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Packs (files that store many object in compressed form,
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along with index files to allow them to be randomly
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accessed) are found in this directory.
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objects/info::
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Additional information about the object store is
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recorded in this directory.
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objects/info/packs::
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This file is to help dumb transports discover what packs
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are available in this object store. Whenever a pack is
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added or removed, `git update-server-info` should be run
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to keep this file up-to-date if the repository is
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published for dumb transports. 'git repack' does this
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by default.
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objects/info/alternates::
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This file records paths to alternate object stores that
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this object store borrows objects from, one pathname per
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line. Note that not only native Git tools use it locally,
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but the HTTP fetcher also tries to use it remotely; this
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will usually work if you have relative paths (relative
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to the object database, not to the repository!) in your
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alternates file, but it will not work if you use absolute
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paths unless the absolute path in filesystem and web URL
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is the same. See also 'objects/info/http-alternates'.
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objects/info/http-alternates::
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This file records URLs to alternate object stores that
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this object store borrows objects from, to be used when
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the repository is fetched over HTTP.
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refs::
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References are stored in subdirectories of this
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directory. The 'git prune' command knows to preserve
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objects reachable from refs found in this directory and
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its subdirectories.
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refs/heads/`name`::
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records tip-of-the-tree commit objects of branch `name`
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refs/tags/`name`::
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records any object name (not necessarily a commit
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object, or a tag object that points at a commit object).
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refs/remotes/`name`::
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records tip-of-the-tree commit objects of branches copied
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from a remote repository.
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refs/replace/`<obj-sha1>`::
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records the SHA-1 of the object that replaces `<obj-sha1>`.
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This is similar to info/grafts and is internally used and
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maintained by linkgit:git-replace[1]. Such refs can be exchanged
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between repositories while grafts are not.
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packed-refs::
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records the same information as refs/heads/, refs/tags/,
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and friends record in a more efficient way. See
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linkgit:git-pack-refs[1].
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HEAD::
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A symref (see glossary) to the `refs/heads/` namespace
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describing the currently active branch. It does not mean
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much if the repository is not associated with any working tree
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(i.e. a 'bare' repository), but a valid Git repository
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*must* have the HEAD file; some porcelains may use it to
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guess the designated "default" branch of the repository
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(usually 'master'). It is legal if the named branch
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'name' does not (yet) exist. In some legacy setups, it is
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a symbolic link instead of a symref that points at the current
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branch.
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+
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HEAD can also record a specific commit directly, instead of
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being a symref to point at the current branch. Such a state
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is often called 'detached HEAD.' See linkgit:git-checkout[1]
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for details.
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branches::
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A slightly deprecated way to store shorthands to be used
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to specify a URL to 'git fetch', 'git pull' and 'git push'.
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A file can be stored as `branches/<name>` and then
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'name' can be given to these commands in place of
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'repository' argument. See the REMOTES section in
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linkgit:git-fetch[1] for details. This mechanism is legacy
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and not likely to be found in modern repositories.
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hooks::
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Hooks are customization scripts used by various Git
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commands. A handful of sample hooks are installed when
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'git init' is run, but all of them are disabled by
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default. To enable, the `.sample` suffix has to be
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removed from the filename by renaming.
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Read linkgit:githooks[5] for more details about
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each hook.
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index::
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The current index file for the repository. It is
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usually not found in a bare repository.
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sharedindex.<SHA-1>::
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The shared index part, to be referenced by $GIT_DIR/index and
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other temporary index files. Only valid in split index mode.
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info::
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Additional information about the repository is recorded
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in this directory.
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info/refs::
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This file helps dumb transports discover what refs are
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available in this repository. If the repository is
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published for dumb transports, this file should be
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regenerated by 'git update-server-info' every time a tag
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or branch is created or modified. This is normally done
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from the `hooks/update` hook, which is run by the
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'git-receive-pack' command when you 'git push' into the
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repository.
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info/grafts::
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This file records fake commit ancestry information, to
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pretend the set of parents a commit has is different
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from how the commit was actually created. One record
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per line describes a commit and its fake parents by
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listing their 40-byte hexadecimal object names separated
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by a space and terminated by a newline.
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+
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Note that the grafts mechanism is outdated and can lead to problems
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transferring objects between repositories; see linkgit:git-replace[1]
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for a more flexible and robust system to do the same thing.
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info/exclude::
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This file, by convention among Porcelains, stores the
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exclude pattern list. `.gitignore` is the per-directory
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ignore file. 'git status', 'git add', 'git rm' and
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'git clean' look at it but the core Git commands do not look
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at it. See also: linkgit:gitignore[5].
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info/sparse-checkout::
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This file stores sparse checkout patterns.
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See also: linkgit:git-read-tree[1].
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remotes::
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Stores shorthands for URL and default refnames for use
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when interacting with remote repositories via 'git fetch',
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'git pull' and 'git push' commands. See the REMOTES section
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in linkgit:git-fetch[1] for details. This mechanism is legacy
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and not likely to be found in modern repositories.
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logs::
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Records of changes made to refs are stored in this
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directory. See linkgit:git-update-ref[1]
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for more information.
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logs/refs/heads/`name`::
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Records all changes made to the branch tip named `name`.
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logs/refs/tags/`name`::
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Records all changes made to the tag named `name`.
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shallow::
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This is similar to `info/grafts` but is internally used
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and maintained by shallow clone mechanism. See `--depth`
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option to linkgit:git-clone[1] and linkgit:git-fetch[1].
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modules::
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Contains the git-repositories of the submodules.
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SEE ALSO
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--------
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linkgit:git-init[1],
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linkgit:git-clone[1],
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linkgit:git-fetch[1],
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linkgit:git-pack-refs[1],
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linkgit:git-gc[1],
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linkgit:git-checkout[1],
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linkgit:gitglossary[7],
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link:user-manual.html[The Git User's Manual]
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GIT
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---
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Part of the linkgit:git[1] suite.
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