Merging two repositories in Git

#git
2018/12/25

Merry Christmas!

If you have two repositories that you'd like to merge into one, you can merge a branch of one repository into the other and then merge them into one merge commit. This is useful if you have repositories of the format Project, New Project, New Project 2, and so on.

The steps are as follows:

  1. cd into the newer repository

  2. Add the older repository as a remote

    git remote add old https://example.com/older/repo

  3. Fetch this remote

    git fetch --tags old

  4. Merge in the branch you'd like to preserve from the older repository into the newer repository

    git merge old/oldbranch -s ours --allow-unrelated-histories

The tip of the repository will now contain a merge commit of the new repository and the tip of the branch of the old repository, with the working tree looking exactly like the newer repository. The old repository will exist in the history as a brand new origin commit, that is eventually merged into the new repository's history.