2. Git Subtree

2.1. Add subtree

$ git log -1
commit 945d1d8d300b1ceef3378b5520ebdaa337655eac
Author: Matt Harasymczuk <book@astronaut.center>
Date:   Thu Nov 28 00:06:53 2019 +0100

    First Commit

$ git remote add revealjs https://github.com/hakimel/reveal.js.git

$ git remote
origin
revealjs

$ git subtree add --prefix=contrib/ revealjs master
git fetch revealjs master
warning: no common commits
remote: Enumerating objects: 11232, done.
remote: Total 11232 (delta 0), reused 0 (delta 0), pack-reused 11232
Receiving objects: 100% (11232/11232), 8.88 MiB | 2.15 MiB/s, done.
Resolving deltas: 100% (6214/6214), done.
From https://github.com/hakimel/reveal.js
 * branch            master     -> FETCH_HEAD
 * [new branch]      master     -> revealjs/master
Added dir 'contrib'

$ git log -2
commit d86741484366d84108f62f1e6120e7ed6613d8d3 (HEAD -> master)
Merge: 945d1d8 33bed47
Author: Matt Harasymczuk <book@astronaut.center>
Date:   Thu Nov 28 00:08:05 2019 +0100

    Add 'contrib/' from commit '33bed47daca3f08c396215415e6ece005970734a'

    git-subtree-dir: contrib
    git-subtree-mainline: 945d1d8d300b1ceef3378b5520ebdaa337655eac
    git-subtree-split: 33bed47daca3f08c396215415e6ece005970734a

commit 945d1d8d300b1ceef3378b5520ebdaa337655eac
Author: Matt Harasymczuk <book@astronaut.center>
Date:   Thu Nov 28 00:06:53 2019 +0100

    First Commit

$ ls contrib
CONTRIBUTING.md         demo.html               package-lock.json
LICENSE                 gruntfile.js            package.json
README.md               index.html              plugin
bower.json              js                      test
css                     lib

2.2. Pull

$ git subtree pull --prefix=contrib/ revealjs master --squash
From https://github.com/hakimel/reveal.js
 * branch            master     -> FETCH_HEAD
Subtree is already at commit 33bed47daca3f08c396215415e6ece005970734a.

2.3. Push

$ git subtree push --prefix=contrib/ origin master