merge-repo.sh

#!/bin/bash

set -e

source=""
target=""

function usage() {
    echo ""
    echo "Usage: "
    echo "merge-repo.sh -s <source> -t <target>"
    echo ""
    echo "-s: Source path."
    echo "-t: Target path."
    echo "-h: Display this help and exit."
    echo ""
}

while getopts "s:t:h" opts; do
    case $opts in
    s)
        source=${OPTARG}
        ;;
    t)
        target=${OPTARG}
        ;;
    h)
        usage
        exit 0
        ;;
    \?)
        usage
        exit 1
        ;;
    esac
done

if [ ! $source ]; then
    echo "Please specify the source path."
    echo "Use -h for help."
    exit 1
fi

if [ ! $target ]; then
    echo "Please specify the target path."
    echo "Use -h for help."
    exit 1
fi

tmp_uuid=`uuidgen`
tmp_dir=tmp-$tmp_uuid
tmp_repo=tmp-repo-$tmp_uuid
tmp_branch=tmp-branch-$tmp_uuid

git clone $source $tmp_dir
cd $tmp_dir
git filter-repo --path-regex .+ --to-subdirectory-filter $target
cd ..
git remote add $tmp_repo $tmp_dir
git fetch $tmp_repo
git branch $tmp_branch $tmp_repo/master
git merge $tmp_branch --allow-unrelated-histories
git branch -d $tmp_branch
git remote rm $tmp_repo
rm -rf $tmp_dir

sudo apt install git-filter-repo