How to `git submodule add` Existing sub Repository?

Question

The Question

How to add existing sub repository as a submodule in git?

The Why

I have a private codespace supermodule with submodule

Answer 1

One way to do it is to manually create the .gitmodules file.

The format is below:

[submodule "path/to/submodule1"]
    path = path/to/submodule/1
    url = git@github.com:user/submodule1
[submodule "path/to/submodule2"]
    path = path/to/submodule/2
    url = git@github.com:user/submodule2

Note you'll have to run

git submodule sync

to apply the changes