import java.util.*;

 import java.io.*;

 public class Example {

     public static void main(String[] args){

         readFile("proxy.txt",0);

         readFile("proxy.txt",1);

         readFile("proxy.txt",4);

         execSystemCmd("notepad"); // windows cmd

         execSystemCmd("ls /home/whucs");

         execSystemCmd("tail -n /home/whucs/vote.py");

         execSystemCmd("wc -l php-fpm.log"); // count lines of a file. 500MB ~ 2s

     }

     public static void readFile(String path, int beginLine) {

         FileInputStream inputStream = null;

         Scanner sc = null;

         try {

             inputStream = new FileInputStream(path);

             sc = new Scanner(inputStream, "UTF-8");

             int begin = 0;

             if (beginLine == 0) beginLine = 1;

             while (sc.hasNextLine()) {

                 begin ++;

                 if (begin >= beginLine) {

                     String line = sc.nextLine();

                     // TODO...

                     System.out.println(line);

                 } else {

                     sc.nextLine();

                 }

             }

             if (begin < beginLine) {

                 System.out.println("error! beginLine > file's total lines.");

             }

             inputStream.close();

             sc.close();

         } catch (IOException e) {

             System.out.println("FileReader IOException!");

             e.printStackTrace();

         }

     }

     public static void execSystemCmd(String cmd) {

         String outPut = null;

         System.out.println("cmd=" + cmd);

         try

         {

             Process p = Runtime.getRuntime().exec(cmd);

             InputStream is = p.getInputStream();

             BufferedReader br = new BufferedReader(new InputStreamReader(is));

             StringBuilder buf = new StringBuilder();

             String line = null;

             while ((line = br.readLine()) != null)    buf.append(line + "\n");

             outPut = buf.toString();

             System.out.printf("outPut = %s",outPut);

         }

         catch (IOException e)

         {

             e.printStackTrace();

         }

     }

 }