Git subtree split two directories

Question

I\'ve been following this excellent answer to extract a subdirectory of my git repository into its own repository, while retaining the complete history.

My repositor

Answer 1

Depending on your needs you might get away with git filter-branch.

I'm not entirely sure what you are trying to achieve, but if you merely want to have a repository with two directories removed (in the history?) this is probably your best shot.

See also Rewriting Git History.

$ git filter-branch --tree-filter 'rm -rf tests/http src/http' --prune-empty HEAD

This will look into each commit and remove the two directories from this commit. Be aware that this rewrites history (i.e.: alters your commit sha) and will cause headaches if you have a common history with another repository.

Answer 2

Use git-subtree add to split-in

# First create two *split-out* branches
cd /repos/repo-to-split
git subtree split --prefix=src/math --branch=math-src
git subtree split --prefix=test/math --branch=math-test

# Now create the new repo
mkdir /repos/math
cd /repos/math
git init

# This approach has a gotcha:
# You must commit something so "revision history begins",
# or `git subtree add` will complain about.
# In this example, an empty `.gitignore` is commited.
touch .gitignore
git add .gitignore
git commit -m "add empty .gitignore to allow using git-subtree"

# Finally, *split-in* the two branches
git subtree add --prefix=src/math ../repo-to-split math-src
git subtree add --prefix=test/math ../repo-to-split math-test

It worked for me with git --version 2.23.0. Also note that you can setup different prefixes at split-in time, i.e. add the src/math/ to src/ and test/math/ to test/.

Side note: use git log at the new repo before commiting to a remote, to see if resultant history is ok enought for you. In my case I have some commits with duplicated messages, because my repo history was so dirty, but it's ok for me.

Source

Answer 3

Use git-filter-repo This is not part of git as of version 2.25. This requires Python3 (>=3.5) and git 2.22.0

git filter-repo --path src/math --path tests/math 

For my repo that contained ~12000 commits git-filter-branch took more than 24 hours and git-filter-repo took less than a minute.