java中如何执行xshell命令

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Lin {
	public static void main(String[] args) {  
		    Process process =null;
              //chmod 777 有时需要给文件权限
               //备注 在Android上执行可能需要su权限	
		    String command1 = "md5sum "  " /root/lin";//命令加路径
		    try {
				process = Runtime.getRuntime().exec(command1);//执行命令		
                
			    InputStreamReader ips = new InputStreamReader(process.getInputStream());
			    BufferedReader br = new BufferedReader(ips);
			    String line;
		    	while ((line = br.readLine()) != null) {
					System.out.println(line);					
				}
		    } catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} 
	}
}