code: private String executeCommand(String command) {
          System.out.println("Execute: " + command);
  
          StringBuilder output = new StringBuilder();
          Process       p;
          try {
              p = Runtime.getRuntime().exec(command);
              p.waitFor();
              BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
              String         line;
              while ((line = reader.readLine()) != null) {
                  output.append(line).append("\n");
              }
          } catch (Exception e) {
              throw new WebpIOException(e);
          }
          if (!"".equals(output.toString())) {
              System.out.println("Output: " + output);
          }
          return "";
      }
docs: execute command
  
  @param command command direct
  @return