Forking a sub directory of a repository on GitHub and making it part of my own repo
git, git-subtree, github, repository, xbmc
Solution
This is mostly possible with `git`, though it is not a typical use case, so there may be some rough edges as you do this (especially if you are new to `git`).
The tool that we'll use for this job is `git subtree`.
Setting up a repository
Start by cloning the whole XBMC repository.
git clone https://github.com/xbmc/xbmc.git
cd xbmc
We start on the `master` branch by default. We want to make our own `master` branch, so let's rename `master` to `upstream-master`.
git branch -m upstream-master
Now use `git subtree split` to only include the part that you want. We'll make the split off part a new branch called `upstream-skin`.
git subtree split --prefix=addons/skin.confluence -b upstream-skin
git checkout upstream-skin
This gives you a new `upstream-skin` branch that only contains the contents of `addons/skin.confluence`, and with a filtered history that contains only the commits that modified files in `addons/skin.confluence`.
Now, let's set up our remotes. Since you cloned `xbmc/xbmc.git`, the `origin` remote will point there. Let's rename that to `upstream`.
git remote rename origin upstream
Make a repository on Github to contain your modifications to `addons/skin.confluence`. As an example, I'll use tbekolay/xbmc-skin, but replace this with your own repo. Add this repo as a remote, and push your `upstream-skin` branch to it.
git remote add origin https://github.com/tbekolay/xbmc-skin.git
git fetch origin
git push -u origin upstream-skin
Finally, we'll make a new branch called `master` that will contain your changes.
git checkout -b master
git push -u origin master
You now have a "fork" of the `addons/skin.confluence` subdirectory.
Making changes to your repositories
When you're dealing with your own local and remote repositories, you can use normal `git` commands. Make sure to do this on the `master` branch (or some other branch, if you'd like) and not the `upstream-skin` branch, which should only ever contain commits from the upstream project.
git checkout master
echo "My XBMC Skin" > README
git add README
git commit -m "Added README"
git push
Receiving upstream commits
When you're dealing with the upstream repository, you will have to use a mix of `git` and `git subtree` commands. To get new filtered commits, we need to do it in three stages.
In the first stage, we'll update `upstream-master` to the current version of the XBMC repository.
git checkout upstream-master
git pull
This should pull down new commits, if there are any.
Next, we will update `upstream-skin` with the new filtered version of the commits. Since `git subtree` ensures that commit hashes will be the same, this should be a clean process. Note that you want to run these commands while still on the `upstream-master` branch.
git subtree split --prefix=addons/skin.confluence \
--onto upstream-skin -b upstream-skin
With `upstream-skin` now updated, you can update your `master` branch as you see fit (either by merging or rebasing).
git checkout master
git rebase upstream-skin
Note that the XBMC repository is gigantic, and the `git subtree` commands will take quite a bit of time to filter through all that history -- and since you're regenerating the split subtree each time you interact with the remote repository, it's quite an expensive operation. I'm not sure if this can be sped up.
This blog post goes into some more detail on the commands above. Also see the `git-subtree` docs for even more detail.
Problem
Apologies, I am very new to Git and GitHub, I've read through a few things but I'm not sure if what I'm trying to do is entirely possible. Basically I want to fork the Confluence Skin used on XBMC and modify various elements located here: https://github.com/xbmc/xbmc/tree/master/addons/skin.confluence However I don't want to fork the entire XBMC repository, so a simple fork action won't do. Here are my general requirements: I would like to take the contents of the skin.confluence folder and put it into a repository on my own GitHub account I need to be able to keep it linked within the original XBMC repo to receive upstream commits, as my modifications will generally be theme based, rather than functionality. Thanks to the response posted by tbekolay, I have been able to do a subtree split to take only the skin.confluence part of repo and essentially create a branch, however I am unsure on how to keep it linked with the original XBMC repo while being pushed to my own repo with my modifications.