How can I have linked dependencies in a git repo?

Question

In my scripts, I often use libraries (mine or others') that have their own repos. I don't want to duplicate those in my repo and get stuck with updating them every time a new version comes out. However, when somebody clones the repo, it should still work locally and not have broken links. Any ideas about what I could do?

Accepted Answer

You can do this with submodules in git. In your repository, do:

```
git submodule add path_to_repo path_where_you_want_it
```

So, if the library's repository had a URL of `git://github.com/example/some_lib.git` and you wanted it at `lib/some_lib` in your project, you'd enter:

```
git submodule add git://github.com/example/some_lib.git lib/some_lib
```

Note that this needs to be done from the top-level directory in your repository. So don't `cd` into the directory where you're putting it first.

After you add a submodule, or whenever someone does a fresh checkout of your repository, you'll need to do:

```
git submodule init
git submodule update
```

And then all submodules you've added will be checked out at the same revision you have.

When you want to update to a newer version of one of the libraries, `cd` into the submodule and pull:

```
cd lib/some_lib
git pull
```

Then, when you do a `git status` you should see `lib/somelib` listed in the modified section. Add that file, commit, and you're up to date. When a collaborator pulls that commit into their repository, they'll see `lib/somelib` as modified until they run `git submodule update` again.

How can I have linked dependencies in a git repo?

Solution

Problem