code: public static File saveDir() {
      String dir = System.getProperty("sqlline.rcfile");
      if (dir != null && dir.length() > 0) {
        return new File(dir);
      }
  
      String baseDir = System.getProperty(SqlLine.SQLLINE_BASE_DIR);
      if (baseDir != null && baseDir.length() > 0) {
        File saveDir = new File(baseDir).getAbsoluteFile();
        saveDir.mkdirs();
        return saveDir;
      }
  
      File f =
          new File(
              System.getProperty("user.home"),
              ((System.getProperty("os.name")
                  .toLowerCase(Locale.ROOT).contains("windows"))
                  ? "" : ".") + "sqlline")
              .getAbsoluteFile();
      try {
        f.mkdirs();
      } catch (Exception e) {
        // ignore
      }
  
      return f;
    }
docs: The save directory if HOME/.sqlline/ on UNIX, and HOME/sqlline/ on
  Windows.
  
  @return save directory