git-submodule - Initialize, update or inspect submodules
git submodule [--quiet] add [-b <branch>] [-f|--force] [--name <name>] [--reference <repository>] [--depth <depth>] [--] <repository> [<path>] git submodule [--quiet] status [--cached] [--recursive] [--] [<path>...] git submodule [--quiet] init [--] [<path>...] git submodule [--quiet] deinit [-f|--force] (--all|[--] <path>...) git submodule [--quiet] update [--init] [--remote] [-N|--no-fetch] [--[no-]recommend-shallow] [-f|--force] [--rebase|--merge] [--reference <repository>] [--depth <depth>] [--recursive] [--jobs <n>] [--] [<path>...] git submodule [--quiet] summary [--cached|--files] [(-n|--summary-limit) <n>] [commit] [--] [<path>...] git submodule [--quiet] foreach [--recursive] <command> git submodule [--quiet] sync [--recursive] [--] [<path>...]
Inspects, updates and manages submodules. A submodule allows you to keep another Git repository in a subdirectory of your repository. The other repository has its own history, which does not interfere with the history of the current repository. This can be used to have external dependencies such as third party libraries for example. When cloning or pulling a repository containing submodules however, these will not be checked out by default; the init and update subcommands will maintain submodules checked out and at appropriate revision in your working tree. Submodules are composed from a so-called gitlink tree entry in the main repository that refers to a particular commit object within the inner repository that is completely separate. A record in the .gitmodules (see gitmodules(5)) file at the root of the source tree assigns a logical name to the submodule and describes the default URL the submodule shall be cloned from. The logical name can be used for overriding this URL within your local repository configuration (see submodule init). Submodules are not to be confused with remotes, which are other repositories of the same project; submodules are meant for different projects you would like to make part of your source tree, while the history of the two projects still stays completely independent and you cannot modify the contents of the submodule from within the main project. If you want to merge the project histories and want to treat the aggregated whole as a single project from then on, you may want to add a remote for the other project and use the subtree merge strategy, instead of treating the other project as a submodule. Directories that come from both projects can be cloned and checked out as a whole if you choose to go that route.
add Add the given repository as a submodule at the given path to the changeset to be committed next to the current project: the current project is termed the "superproject". This requires at least one argument: <repository>. The optional argument <path> is the relative location for the cloned submodule to exist in the superproject. If <path> is not given, the "humanish" part of the source repository is used ("repo" for "/path/to/repo.git" and "foo" for "host.xz:foo/.git"). The <path> is also used as the submodule's logical name in its configuration entries unless --name is used to specify a logical name. <repository> is the URL of the new submodule's origin repository. This may be either an absolute URL, or (if it begins with ./ or ../), the location relative to the superproject's origin repository (Please note that to specify a repository foo.git which is located right next to a superproject bar.git, you'll have to use ../foo.git instead of ./foo.git - as one might expect when following the rules for relative URLs - because the evaluation of relative URLs in Git is identical to that of relative directories). If the superproject doesn't have an origin configured the superproject is its own authoritative upstream and the current working directory is used instead. <path> is the relative location for the cloned submodule to exist in the superproject. If <path> does not exist, then the submodule is created by cloning from the named URL. If <path> does exist and is already a valid Git repository, then this is added to the changeset without cloning. This second form is provided to ease creating a new submodule from scratch, and presumes the user will later push the submodule to the given URL. In either case, the given URL is recorded into .gitmodules for use by subsequent users cloning the superproject. If the URL is given relative to the superproject's repository, the presumption is the superproject and submodule repositories will be kept together in the same relative location, and only the superproject's URL needs to be provided: git-submodule will correctly locate the submodule using the relative URL in .gitmodules. status Show the status of the submodules. This will print the SHA-1 of the currently checked out commit for each submodule, along with the submodule path and the output of git describe for the SHA-1. Each SHA-1 will be prefixed with - if the submodule is not initialized, + if the currently checked out submodule commit does not match the SHA-1 found in the index of the containing repository and U if the submodule has merge conflicts. If --recursive is specified, this command will recurse into nested submodules, and show their status as well. If you are only interested in changes of the currently initialized submodules with respect to the commit recorded in the index or the HEAD, git-status(1) and git-diff(1) will provide that information too (and can also report changes to a submodule's work tree). init Initialize the submodules recorded in the index (which were added and committed elsewhere) by copying submodule names and urls from .gitmodules to .git/config. Optional <path> arguments limit which submodules will be initialized. It will also copy the value of submodule.$name.update into .git/config. The key used in .git/config is submodule.$name.url. This command does not alter existing information in .git/config. You can then customize the submodule clone URLs in .git/config for your local setup and proceed to git submodule update; you can also just use git submodule update --init without the explicit init step if you do not intend to customize any submodule locations. deinit Unregister the given submodules, i.e. remove the whole submodule.$name section from .git/config together with their work tree. Further calls to git submodule update, git submodule foreach and git submodule sync will skip any unregistered submodules until they are initialized again, so use this command if you don't want to have a local checkout of the submodule in your working tree anymore. If you really want to remove a submodule from the repository and commit that use git-rm(1) instead. When the command is run without pathspec, it errors out, instead of deinit-ing everything, to prevent mistakes. If --force is specified, the submodule's working tree will be removed even if it contains local modifications. update Update the registered submodules to match what the superproject expects by cloning missing submodules and updating the working tree of the submodules. The "updating" can be done in several ways depending on command line options and the value of submodule.<name>.update configuration variable. Supported update procedures are: checkout the commit recorded in the superproject will be checked out in the submodule on a detached HEAD. This is done when --checkout option is given, or no option is given, and submodule.<name>.update is unset, or if it is set to checkout. If --force is specified, the submodule will be checked out (using git checkout --force if appropriate), even if the commit specified in the index of the containing repository already matches the commit checked out in the submodule. rebase the current branch of the submodule will be rebased onto the commit recorded in the superproject. This is done when --rebase option is given, or no option is given, and submodule.<name>.update is set to rebase. merge the commit recorded in the superproject will be merged into the current branch in the submodule. This is done when --merge option is given, or no option is given, and submodule.<name>.update is set to merge. custom command arbitrary shell command that takes a single argument (the sha1 of the commit recorded in the superproject) is executed. This is done when no option is given, and submodule.<name>.update has the form of !command. When no option is given and submodule.<name>.update is set to none, the submodule is not updated. If the submodule is not yet initialized, and you just want to use the setting as stored in .gitmodules, you can automatically initialize the submodule with the --init option. If --recursive is specified, this command will recurse into the registered submodules, and update any nested submodules within. summary Show commit summary between the given commit (defaults to HEAD) and working tree/index. For a submodule in question, a series of commits in the submodule between the given super project commit and the index or working tree (switched by --cached) are shown. If the option --files is given, show the series of commits in the submodule between the index of the super project and the working tree of the submodule (this option doesn't allow to use the --cached option or to provide an explicit commit). Using the --submodule=log option with git-diff(1) will provide that information too. foreach Evaluates an arbitrary shell command in each checked out submodule. The command has access to the variables $name, $path, $sha1 and $toplevel: $name is the name of the relevant submodule section in .gitmodules, $path is the name of the submodule directory relative to the superproject, $sha1 is the commit as recorded in the superproject, and $toplevel is the absolute path to the top-level of the superproject. Any submodules defined in the superproject but not checked out are ignored by this command. Unless given --quiet, foreach prints the name of each submodule before evaluating the command. If --recursive is given, submodules are traversed recursively (i.e. the given shell command is evaluated in nested submodules as well). A non-zero return from the command in any submodule causes the processing to terminate. This can be overridden by adding || : to the end of the command. As an example, git submodule foreach 'echo $path `git rev-parse HEAD`' will show the path and currently checked out commit for each submodule. sync Synchronizes submodules' remote URL configuration setting to the value specified in .gitmodules. It will only affect those submodules which already have a URL entry in .git/config (that is the case when they are initialized or freshly added). This is useful when submodule URLs change upstream and you need to update your local repositories accordingly. "git submodule sync" synchronizes all submodules while "git submodule sync -- A" synchronizes submodule "A" only. If --recursive is specified, this command will recurse into the registered submodules, and sync any nested submodules within.
-q, --quiet Only print error messages. --all This option is only valid for the deinit command. Unregister all submodules in the working tree. -b, --branch Branch of repository to add as submodule. The name of the branch is recorded as submodule.<name>.branch in .gitmodules for update --remote. A special value of . is used to indicate that the name of the branch in the submodule should be the same name as the current branch in the current repository. -f, --force This option is only valid for add, deinit and update commands. When running add, allow adding an otherwise ignored submodule path. When running deinit the submodule working trees will be removed even if they contain local changes. When running update (only effective with the checkout procedure), throw away local changes in submodules when switching to a different commit; and always run a checkout operation in the submodule, even if the commit listed in the index of the containing repository matches the commit checked out in the submodule. --cached This option is only valid for status and summary commands. These commands typically use the commit found in the submodule HEAD, but with this option, the commit stored in the index is used instead. --files This option is only valid for the summary command. This command compares the commit in the index with that in the submodule HEAD when this option is used. -n, --summary-limit This option is only valid for the summary command. Limit the summary size (number of commits shown in total). Giving 0 will disable the summary; a negative number means unlimited (the default). This limit only applies to modified submodules. The size is always limited to 1 for added/deleted/typechanged submodules. --remote This option is only valid for the update command. Instead of using the superproject's recorded SHA-1 to update the submodule, use the status of the submodule's remote-tracking branch. The remote used is branch's remote (branch.<name>.remote), defaulting to origin. The remote branch used defaults to master, but the branch name may be overridden by setting the submodule.<name>.branch option in either .gitmodules or .git/config (with .git/config taking precedence). This works for any of the supported update procedures (--checkout, --rebase, etc.). The only change is the source of the target SHA-1. For example, submodule update --remote --merge will merge upstream submodule changes into the submodules, while submodule update --merge will merge superproject gitlink changes into the submodules. In order to ensure a current tracking branch state, update --remote fetches the submodule's remote repository before calculating the SHA-1. If you don't want to fetch, you should use submodule update --remote --no-fetch. Use this option to integrate changes from the upstream subproject with your submodule's current HEAD. Alternatively, you can run git pull from the submodule, which is equivalent except for the remote branch name: update --remote uses the default upstream repository and submodule.<name>.branch, while git pull uses the submodule's branch.<name>.merge. Prefer submodule.<name>.branch if you want to distribute the default upstream branch with the superproject and branch.<name>.merge if you want a more native feel while working in the submodule itself. -N, --no-fetch This option is only valid for the update command. Don't fetch new objects from the remote site. --checkout This option is only valid for the update command. Checkout the commit recorded in the superproject on a detached HEAD in the submodule. This is the default behavior, the main use of this option is to override submodule.$name.update when set to a value other than checkout. If the key submodule.$name.update is either not explicitly set or set to checkout, this option is implicit. --merge This option is only valid for the update command. Merge the commit recorded in the superproject into the current branch of the submodule. If this option is given, the submodule's HEAD will not be detached. If a merge failure prevents this process, you will have to resolve the resulting conflicts within the submodule with the usual conflict resolution tools. If the key submodule.$name.update is set to merge, this option is implicit. --rebase This option is only valid for the update command. Rebase the current branch onto the commit recorded in the superproject. If this option is given, the submodule's HEAD will not be detached. If a merge failure prevents this process, you will have to resolve these failures with git-rebase(1). If the key submodule.$name.update is set to rebase, this option is implicit. --init This option is only valid for the update command. Initialize all submodules for which "git submodule init" has not been called so far before updating. --name This option is only valid for the add command. It sets the submodule's name to the given string instead of defaulting to its path. The name must be valid as a directory name and may not end with a /. --reference <repository> This option is only valid for add and update commands. These commands sometimes need to clone a remote repository. In this case, this option will be passed to the git-clone(1) command. NOTE: Do not use this option unless you have read the note for git- clone(1)'s --reference and --shared options carefully. --recursive This option is only valid for foreach, update, status and sync commands. Traverse submodules recursively. The operation is performed not only in the submodules of the current repo, but also in any nested submodules inside those submodules (and so on). --depth This option is valid for add and update commands. Create a shallow clone with a history truncated to the specified number of revisions. See git-clone(1) --[no-]recommend-shallow This option is only valid for the update command. The initial clone of a submodule will use the recommended submodule.<name>.shallow as provided by the .gitmodules file by default. To ignore the suggestions use --no-recommend-shallow. -j <n>, --jobs <n> This option is only valid for the update command. Clone new submodules in parallel with as many jobs. Defaults to the submodule.fetchJobs option. <path>... Paths to submodule(s). When specified this will restrict the command to only operate on the submodules found at the specified paths. (This argument is required with add).
When initializing submodules, a .gitmodules file in the top-level directory of the containing repository is used to find the url of each submodule. This file should be formatted in the same way as $GIT_DIR/config. The key to each submodule url is "submodule.$name.url". See gitmodules(5) for details.
Part of the git(1) suite
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.