Import existing git repo into sub directory of another git repo.

merge_to_sub.sh

#!/bin/bash
# NOTE: 
# You couldn't track original branch (which would imported under current repo) history from current repo. 

if [ "$#" -ne 2 ]; then
    echo "Usage: $0 prefix url"
    exit 0
fi

NAME=$1
URL=$2
PREFIX=${NAME}
TEMP_BRANCH=${NAME}_branch

git remote add $NAME $URL
git fetch $NAME
git checkout -b ${TEMP_BRANCH} ${NAME}/master
git checkout master
git read-tree --prefix=${PREFIX}/ -u ${TEMP_BRANCH}

#
echo "'${NAME}/master' from '${URL}' is now under '${PREFIX}' in curreunt repo."
echo "You can commit your changes now."