Commit c47f1024 authored by Petr Baudis's avatar Petr Baudis Committed by Junio C Hamano

Documentation/git-submodule.txt: Further clarify the description

This patch rewrites the general description yet again, first clarifying
the high-level concept, mentioning the difference to remotes and using
the subtree merge strategy, then getting to the details about tree
entries and .gitmodules file.

The patch also makes few smallar grammar fixups within the rest of the
description and clarifies how does 'init' relate to 'update --init'.

Cc: Heikki Orsila <[email protected]>
Signed-off-by: default avatarPetr Baudis <[email protected]>
Signed-off-by: default avatarJunio C Hamano <[email protected]>
parent c09df8a7
......@@ -18,24 +18,44 @@ SYNOPSIS
DESCRIPTION
-----------
Submodules are a special kind of tree entries which refer to a particular tree
state in another repository. The tree entry describes
the existence of a submodule with the given name and the exact revision that
should be used, while an entry in `.gitmodules` file gives the location of
the repository.
When checked out, submodules will maintain their own independent repositories
within their directories; the only link between the submodule and the "parent
project" is the tree entry within the parent project mentioned above.
This command will manage the tree entries and contents of the gitmodules file
for you, as well as inspecting the status of your submodules and updating them.
When adding a new submodule to the tree, the 'add' subcommand is to be used.
However, when pulling a tree containing submodules, 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. You can inspect
the current status of your submodules using the 'submodule' subcommand and get
an overview of changes 'update' would perform using the 'summary' subcommand.
Submodules allow foreign repositories to be embedded within
a dedicated subdirectory of the source tree, always pointed
at a particular commit.
They are not to be confused with remotes, which are meant mainly
for branches 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.
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` 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').
This command will manage the tree entries and contents of the
gitmodules file for you, as well as inspect the status of your
submodules and update them.
When adding a new submodule to the tree, the 'add' subcommand
is to be used. However, when pulling a tree containing submodules,
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.
You can briefly inspect the up-to-date status of your submodules
using the 'status' subcommand and get a detailed overview of the
difference between the index and checkouts using the 'summary'
subcommand.
COMMANDS
......@@ -78,10 +98,15 @@ status::
repository. This command is the default command for 'git-submodule'.
init::
Initialize the submodules, i.e. register in .git/config each submodule
name and url found in .gitmodules. The key used in .git/config is
`submodule.$name.url`. This command does not alter existing information
in .git/config.
Initialize the submodules, i.e. register each submodule name
and url found in .gitmodules into .git/config.
The key used in .git/config is `submodule.$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.
update::
Update the registered submodules, i.e. clone missing submodules and
......
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