SOURCE_FILE=$(realpath -m "$1")
TARGET_FILE=$(realpath -m "$2")

mkdir -p "$(dirname "${TARGET_FILE}")"

TEMP_FILE=$(mktemp)
cat "${SOURCE_FILE}" > "${TEMP_FILE}"

if [[ -f "${TARGET_FILE}" ]]; then
  while IFS='=' read -r key value; do
    if ! grep -q "^${key}=" "${TEMP_FILE}"; then
      echo "${key}=${value}" >> "${TEMP_FILE}"
    fi
  done < "${TARGET_FILE}"
fi

mv "${TEMP_FILE}" "${TARGET_FILE}"

echo "Configuration file ${TARGET_FILE} has been updated."