Splitting a subfolder out into a new repository without changing project root directory

git-split.sh

# If you want to change project root, follow 
# https://help.github.com/en/articles/splitting-a-subfolder-out-into-a-new-repository

# More advanced stuff: https://manishearth.github.io/blog/2017/03/05/understanding-git-filter-branch/

# ---------------------------------------------------------------------------------------------------

## STEPS for Splitting a subfolder out into a new repository without changing project root directory

# clone the repo
git clone [email protected]:stashed/stash.git docs

# checkout all the release branches, so that filter-branch can rewrite them

git checkout release-0.1
git checkout release-0.2
git checkout release-0.3
git checkout release-0.4
git checkout release-0.5
git checkout release-0.6
git checkout release-0.7
git checkout release-0.8

# remove unreferenced blobs from git repo
# ref: https://stackoverflow.com/a/14728706/244009

git remote rm origin
rm -rf .git/refs/original/ .git/refs/remotes/ .git/*_HEAD .git/logs/
git for-each-ref --format="%(refname)" refs/original/ | xargs -n1 --no-run-if-empty git update-ref -d

# after this `git reflog` should be empty


# How to use git filter-branch without changing project root?
# https://stackoverflow.com/a/56300480/244009
git filter-branch --prune-empty --tag-name-filter cat --index-filter  '
                git read-tree --empty
                git read-tree --prefix=docs/ $GIT_COMMIT:docs/
        ' -- --all -- docs


## Installer - move hack/deploy to the top and then remove all else

git filter-branch -f --prune-empty --tag-name-filter cat --tree-filter 'mv hack/deploy deploy 1>/dev/null 2>/dev/null; true' -- --all

git filter-branch -f --prune-empty --tag-name-filter cat --index-filter "git rm -rf --cached --ignore-unmatch files_to_delete" -- --all





# Upload to new repo


$ git remote add origin [email protected]:stashed/docs.git
$ git push --all origin -u
$ git push --tag origin -u