Extract a directory based GIT repository to separate repositories keeping all branches and history

extract.sh

#!/bin/sh
# Copyright (C) 2016 Raphaël Doursenaud
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

REPO_URL=''
REPO_NAME=''
# If your directories are at the repository root. Edit the code to remove SUBDIRECTORY references!
SUBDIRECTORY=''

## Clone repo
git clone ${REPO_URL}

cd ${REPO_NAME}

# Update all branches
for branch in $(git for-each-ref refs/remotes/origin --format='%(refname:strip=3)')
do
    echo "Updating branch ${branch}"
    git checkout ${branch}
done

cd ..

# For each directory
for dir in $(ls -d ${REPO_NAME}/${SUBDIRECTORY}/*/)
do
    module=$(basename ${dir})

    echo "Extracting module: ${module}"

    # Clone to a separate repository
    git clone ${REPO_NAME} ${module}
    cd ${module}

    # Filter each branches
    for branch in $(git for-each-ref refs/remotes/origin --format='%(refname:strip=3)')
    do
        echo "Extracting branch: ${branch}"
        git checkout ${branch}
        git filter-branch -f --prune-empty --subdirectory-filter ${SUBDIRECTORY}/${module}
    done

    cd ..
done