Merge git repository in subdirectory

Question

I\'d like to merge a remote git repository in my working git repository as a subdirectory of it. I\'d like the resulting repository to contain the merged history of the two

Answer 1

I wanted to

1. keep a linear history without explicit merge, and
2. make it look like the files of the merged repository had always existed in the subdirectory, and as a side effect make git log -- file work without --follow.

Step 1: Rewrite history in the source repository to make it look like all files always existed below the subdirectory.

Create a temporary branch for the rewritten history.

git checkout -b tmp_subdir

Then use git filter-branch as described in How can I rewrite history so that all files, except the ones I already moved, are in a subdirectory?:

git filter-branch --prune-empty --tree-filter '
if [ ! -e foo/bar ]; then
    mkdir -p foo/bar
    git ls-tree --name-only $GIT_COMMIT | xargs -I files mv files foo/bar
fi'

Step 2: Switch to the target repository. Add the source repository as remote in the target repository and fetch its contents.

git remote add sourcerepo .../path/to/sourcerepo
git fetch sourcerepo

Step 3: Use merge --onto to add the commits of the rewritten source repository on top of the target repository.

git rebase --preserve-merges --onto master --root sourcerepo/tmp_subdir

You can check the log to see that this really got you what you wanted.

git log --stat

Step 4: After the rebase you’re in “detached HEAD” state. You can fast-forward master to the new head.

git checkout -b tmp_merged
git checkout master
git merge tmp_merged
git branch -d tmp_merged

Step 5: Finally some cleanup: Remove the temporary remote.

git remote rm sourcerepo