Git submodule for Linux and Windows

Question

When using git submodule on Linux I might have a .gitmodules with one or more subsystems checked out from e.g. /mnt/gitrepos/subsystem1.git (central file based access).

[submodule "subsystem1"]
  path = subsystem11
  url = /mnt/gitrepos/subsystem1.git/

I would like to support also a Windows user who can access the same module repo from H:/gitrepos/subsystem1.git/.

It is e.g. a Samba share from Linux of /mnt/gitrepos/ as the share gitrepos.

Is there a way where Git can handle the URL line depending on the OS? For Windows the .gitmodules would be

[submodule "subsystem1"]
  path = subsystem11
  url = H:/gitrepos/subsystem1.git/

Thus I would like "something like" this generic code for .gitmodules (speculative syntax):

[submodule "subsystem1"]
  path = subsystem11
  if Linux 
    url = /mnt/gitrepos/subsystem1.git/
  else
    url = H:/gitrepos/subsystem1.git/

Answer 1

No. Submodules are generally designed for one repository URL that works everywhere, usually network-based (e.g. git://host/path). There is no mechanism for providing multiple different URLs for one repository.

That said, Git does allow you to customize a submodule's URL. When submodules are initialized (git submodule init), the URL from .gitmodules is copied to your .git/config file. You can now edit the URLs there before running git submodule update.

Answer 2

One workaround I've considered (but not tried) is to initialize the submodule codebase ("subsystem1.git" in your example) as an independent, local repository. Add a "remote" in the submodule which points to the independent, local version of the repository. Also add a "remote" in the non-submodule (indepent, local) version of your subsystem repository which points to the submodule version. You should then be able to use Samba / Windows / Linux to update the independent (non-submodule) version of subsystem1.git, and then "git fetch independent" from within the submodule to copy the code from the non-submodule repository to the submodule repository.

At the end, your directory structure should look something like:

/mnt/gitrepos/
/mnt/gitrepos/subsystem1.git/
/mnt/subsystem1.git/

The remotes in each of these repositories would look like the following:

/mnt/gitrepos/.git/config would have one remote block:
    [remote "origin"]   (points to your main, non-local repository)
/mnt/subsystem1.git/.git/config would have two remote blocks:
    [remote "origin"]   (points to your main, non-local repository)
    [remote "local_origin"]   (points to /mnt/gitrepos/subsystem1.git)
/mnt/gitrepos/.git/modules/subsystem1.git/config would also have two remote blocks:
    [remote "origin"]   (points to your main, non-local repository)
    [remote "independent"]   (points to /mnt/subsystem1.git)

Synchronizing your submodule's code with what's on the remote server then becomes a multi-step process, since you have to use the "independent" repository as an intermediate repository / staging area.

Your Mileage May Vary... This is just a thing that seems like it should work, not something I've tried.