Command Section
GITSUBMODULES(7)                  Git Manual                  GITSUBMODULES(7)

       gitsubmodules - mounting one repository inside another

       .gitmodules, $GIT_DIR/config

       git submodule
       git <command> --recurse-submodules

       A submodule is a repository embedded inside another repository. The
       submodule has its own history; the repository it is embedded in is
       called a superproject.

       On the filesystem, a submodule usually (but not always - see FORMS
       below) consists of (i) a Git directory located under the
       $GIT_DIR/modules/ directory of its superproject, (ii) a working
       directory inside the superproject's working directory, and a .git file
       at the root of the submodule's working directory pointing to (i).

       Assuming the submodule has a Git directory at $GIT_DIR/modules/foo/ and
       a working directory at path/to/bar/, the superproject tracks the
       submodule via a gitlink entry in the tree at path/to/bar and an entry
       in its .gitmodules file (see gitmodules(5)) of the form = path/to/bar.

       The gitlink entry contains the object name of the commit that the
       superproject expects the submodule's working directory to be at.

       The section* in the .gitmodules file gives additional
       hints to Gits porcelain layer such as where to obtain the submodule via
       the setting.

       Submodules can be used for at least two different use cases:

            1.Using another project while maintaining independent history.
           Submodules allow you to contain the working tree of another project
           within your own working tree while keeping the history of both
           projects separate. Also, since submodules are fixed to an arbitrary
           version, the other project can be independently developed without
           affecting the superproject, allowing the superproject project to
           fix itself to new versions only when desired.

            2.Splitting a (logically single) project into multiple
           repositories and tying them back together. This can be used to
           overcome current limitations of Gits implementation to have finer
           grained access:

               ze of the git repository: In its current form Git scales up
               poorly for large repositories containing content that is not
               compressed by delta computation between trees. However you can
               also use submodules to e.g. hold large binary assets and these
               repositories are then shallowly cloned such that you do not
               have a large history locally.

               ansfer size: In its current form Git requires the whole
               working tree present. It does not allow partial trees to be
               transferred in fetch or clone.

               cess control: By restricting user access to submodules, this
               can be used to implement read/write policies for different

       Submodule operations can be configured using the following mechanisms
       (from highest to lowest precedence):

           e command line for those commands that support taking submodule
           specs. Most commands have a boolean flag --recurse-submodules
           whether to recurse into submodules. Examples are ls-files or
           checkout. Some commands take enums, such as fetch and push, where
           you can specify how submodules are affected.

           e configuration inside the submodule. This includes
           $GIT_DIR/config in the submodule, but also settings in the tree
           such as a .gitattributes or .gitignore files that specify behavior
           of commands inside the submodule.

           For example an effect from the submodule's .gitignore file would be
           observed when you run git status --ignore-submodules=none in the
           superproject. This collects information from the submodule's
           working directory by running status in the submodule, which does
           pay attention to its .gitignore file.

           The submodule's $GIT_DIR/config file would come into play when
           running git push --recurse-submodules=check in the superproject, as
           this would check if the submodule has any changes not published to
           any remote. The remotes are configured in the submodule as usual in
           the $GIT_DIR/config file.

           e configuration file $GIT_DIR/config in the superproject.
           Typical configuration at this place is controlling if a submodule
           is recursed into at all via the active flag for example.

           If the submodule is not yet initialized, then the configuration
           inside the submodule does not exist yet, so configuration where to
           obtain the submodule from is configured here for example.

           e .gitmodules file inside the superproject. Additionally to the
           required mapping between submodule's name and path, a project
           usually uses this file to suggest defaults for the upstream
           collection of repositories.

           This file mainly serves as the mapping between name and path in the
           superproject, such that the submodule's git directory can be

           If the submodule has never been initialized, this is the only place
           where submodule configuration is found. It serves as the last
           fallback to specify where to obtain the submodule from.

       Submodules can take the following forms:

           e basic form described in DESCRIPTION with a Git directory, a
           working directory, a gitlink, and a .gitmodules entry.

           ld-form" submodule: A working directory with an embedded .git
           directory, and the tracking gitlink and .gitmodules entry in the
           superproject. This is typically found in repositories generated
           using older versions of Git.

           It is possible to construct these old form repositories manually.

           When deinitialized or deleted (see below), the submodule's Git
           directory is automatically moved to $GIT_DIR/modules/<name>/ of the

           initialized submodule: A gitlink, and a .gitmodules entry, but
           no submodule working directory. The submodule's git directory may
           be there as after deinitializing the git directory is kept around.
           The directory which is supposed to be the working directory is
           empty instead.

           A submodule can be deinitialized by running git submodule deinit.
           Besides emptying the working directory, this command only modifies
           the superproject's $GIT_DIR/config file, so the superproject's
           history is not affected. This can be undone using git submodule

           leted submodule: A submodule can be deleted by running git rm
           <submodule path> && git commit. This can be undone using git

           The deletion removes the superproject's tracking data, which are
           both the gitlink entry and the section in the .gitmodules file. The
           submodule's working directory is removed from the file system, but
           the Git directory is kept around as it to make it possible to
           checkout past commits without requiring fetching from another

           To completely remove a submodule, manually delete

           # add a submodule
           git submodule add <url> <path>

           # occasionally update the submodule to a new version:
           git -C <path> checkout <new version>
           git add <path>
           git commit -m "update submodule to new version"

           # See the list of submodules in a superproject
           git submodule status

           # See FORMS on removing submodules

           # Enable recursion for relevant commands, such that
           # regular commands recurse into submodules by default
           git config --global submodule.recurse true

           # Unlike the other commands below clone still needs
           # its own recurse flag:
           git clone --recurse <URL> <directory>
           cd <directory>

           # Get to know the code:
           git grep foo
           git ls-files

           # Get new code
           git fetch
           git pull --rebase

           # change worktree
           git checkout
           git reset

       When cloning or pulling a repository containing submodules the
       submodules will not be checked out by default; You can instruct clone
       to recurse into submodules. The init and update subcommands of git
       submodule will maintain submodules checked out and at an appropriate
       revision in your working tree. Alternatively you can set
       submodule.recurse to have checkout recursing into submodules.

       git-submodule(1), gitmodules(5).

       Part of the git(1) suite

Git 2.15.1                        11/28/2017                  GITSUBMODULES(7)
Command Section