/*	RuntimeDemo.java
*	@author: Charles Bell
*	@version: January 6, 2001
*	Example use of Runtime.
*/

import java.io.*;
import java.lang.*;

/**	Executes the String arguments, displays the commands being executed, and displays 
*	any results.
*/
public class RuntimeDemo{

	/** Instantiates a class and runs the commands passed in the aguments.
	*/
	public static void main(String[] args){
		RuntimeDemo demo = new RuntimeDemo();
		demo.runCommand(args);
	}


	/**	Runs the commands in a process and displays the results.
	*/
	public void runCommand(String[] args){
		int number = args.length;
		try{
			String[] commands;
			String operatingsystem = System.getProperty("os.name");
			if (operatingsystem.toLowerCase().indexOf("windows") > 0){
				commands = new String[number + 2];
				commands[0] = "command.com"; //for Windows 95, 98, ME. etc.
				if (operatingsystem.toLowerCase().indexOf("nt") > 0){
					commands[0] = "cmd.exe"; //for Windows NT
				}
				commands[1] = "/c";
				for (int i = 0; i < number;i++){
					commands[i+2] = args[i];
				}
			}else{
				commands = new String[number];
				for (int i = 0; i < number;i++){
					commands[i] = args[i];
				}
			} 

			System.out.print("Executing: ");
			for (int i = 0; i< commands.length;i++){
				 System.out.print(commands[i] + " ");
			}

			Runtime runtime = Runtime.getRuntime();
			Process process = runtime.exec(commands);
			// Because some native platforms only provide limited buffer size 
			// for standard input and output streams, failure to promptly write 
			// the input stream or read the output stream of the subprocess 
			// may cause the subprocess to block, and even deadlock.
			CheckStream csin = new CheckStream(process.getInputStream());
			CheckStream cserr = new CheckStream(process.getErrorStream());
			csin.start();
			cserr.start();
                  System.out.print("Waiting for command process to terminate.");
                  int done = process.waitFor();
                  process.destroy();
                  System.out.println("... Done.");      
          	}catch(InterruptedException ie){
            	System.out.println("InterruptedException: " + ie.getMessage());
		}catch(IOException ioe){
			System.out.println("IOException: " + ioe.getMessage());
		}
	}

	/**	Inner class for checking the results if any of an InputStream.
	*/
	class CheckStream extends Thread{

		BufferedReader br;
		String lineread = "";

		/** 	Constructor needs an InputStream to form an anonymous 
		*	InputStreamReader which is used to create a BufferedReader
		*	for reading the stream. 
		*/
		CheckStream(InputStream is){
			this.br = new BufferedReader(new InputStreamReader(is));		
		}

		/**	Reads the input stream and displays anything returned.
		*/
		public void run(){
			try{
				while ((lineread = br.readLine()) != null){
					System.out.println(lineread);
				}
			}catch(IOException ioe){
				System.out.println("IOException: " + ioe.getMessage());
			}
		}
	}
}