Script to merge one repository into another

Makefile

# Merge SRC_REPO into a DEST_REPO under its subdirectory NEW_DIR
# cf. https://stackoverflow.com/questions/277029/combining-multiple-git-repositories
#
# Place 2 repository and this Makefile as follows:
#
#   ./
#     DEST_REPO/
#     Makefile
#
# Then execute
#
# $ make prepare	# Get ready SRC_DIR for merge
# $ make merge

DEST_REPO := kata
SRC_REPO := kata--potter
NEW_DIR := potter--scala

prepare: clean get-source-repo move-to-sub-dir rewrite-history print

get-source-repo:
	git clone git@github.com:ryu1kn/$(SRC_REPO).git

move-to-sub-dir:
	(cd $(SRC_REPO) && \
	mkdir $(NEW_DIR) && \
	ls -1a | grep -v '^\(\.\+\|\.git\|$(NEW_DIR)\)$$' | xargs -I % git mv % $(NEW_DIR) && \
	git commit -m "Prepare for moving repository")

rewrite-history:
	(cd $(SRC_REPO) && git filter-branch --index-filter \
		'git ls-files -s | sed "s#	#&$(NEW_DIR)/#" | GIT_INDEX_FILE=$GIT_INDEX_FILE.new git update-index --index-info && mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' HEAD )

clean:
	rm -rf $(SRC_REPO)

REVS = $(shell cd $(SRC_REPO) && git rev-list --all)
print:
	@for REV in $(REVS) ; do \
		(cd $(SRC_REPO) && echo $$REV ; git diff-tree --no-commit-id --name-only -r $$REV ) ; \
	done

merge:
	cd $(DEST_REPO) && \
	git pull ../$(SRC_REPO) --allow-unrelated-histories