import java.io.*;  
    import java.util.*;  
      
    public class Test  
    {  
        public static void main(String[] args) throws Exception  
        {  
            ProcessBuilder pb = new ProcessBuilder("CMD.exe", "/C", "SET"); // SET prints out the environment variables  
            pb.redirectErrorStream(true);  
            Map env = pb.environment();  
            String path = env.get("Path") + ";C:\\cygwin\\bin";  
            env.put("Path", path);  
            Process process = pb.start();  
            BufferedReader in = new BufferedReader(new InputStreamReader(process.getInputStream()));  
            String line;  
            while ((line = in.readLine()) != null)  
            {  
                System.out.println(line);  
            }  
        }  
    }