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."