如何从现有存储库创建新的 git 存储库，仅选择存储库中的特定文件夹？

Question

Let's say I have a git repository with three folders A, B, and C. I want to create a new git repository with just folder C ( without A, B ) but with the history preserved. Basically, I want a new git repo with folders A,B deleted and changes in them removed from the history too; a repo with just folder C and the commits which changed the contents of folder C.

Answer 1

Suppose the current repository foo structure is

foo
├── A
├── B
├── C
└── .git

To make it be

foo
├── C
└── .git

# backup the current branch.
# this can be omitted because
# git filter-branch automatically
# makes a backup as refs/original/refs/heads/<branch>
git branch <backup_branch>

# rewrite the current branch, removing A and B from the history
git filter-branch -f --prune-empty --tree-filter 'rm -rf A B'

# if anything goes wrong
# reset to the original status
git reset refs/original/refs/heads/<branch> --hard
# or
git reset <backup_branch> --hard

To make it be

C
└── .git

git filter-branch -f --subdirectory-filter C

In either way, the current branch is rewritten and only the commits that have touched C are preserved (the commit sha1 values are changed).

Push the new branch to the new repository.

git push <path_to_new_repo> HEAD:refs/heads/<branch>