Ubuntu process manipulation

[Asvin]

Hi, I have an assignment that requires a program to do the following things:

1) Create a process and a basic shell script like the one in the terminal in Ubuntu.
2) Show the current directory of the process.
3) Go to and display the home directory, upon entering the command
4) Change to a certain directory, based on user's command
5) Create a history feature that stores all the commands like "ls whatever", "ls anotherwhatever", etc.

I have put together a program that has set up a basic shell called "jsh" and shows the current directory. I am having trouble with the rest of the program! Here is the code:

package ubuntuprocess;

import java.io.BufferedReader;
import java.io.File;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class UbuntuProcess
{
    private static File File;
    public static void main(String[] args) throws java.io.IOException {
        String workingDirectory = System.getProperty("user.dir") + "/";
        String homeDirectory = System.getProperty("user.home") + "/";
        String fileSeparator = System.getProperty("file.separator");
        String newDirectory;
        String commandLine;
        File wd;

        BufferedReader console = new BufferedReader(new InputStreamReader(System.in));

        // we break out with <control><C>
        while (true) {
            // read what they entered
            System.out.print("jsh>");
            commandLine = console.readLine();

            // if they entered a return, just loop again
            if (commandLine.equals(""))
                continue;
         
            // now parse it
            List<String> input = new ArrayList<String>();
            StringTokenizer tokenizer = new StringTokenizer(commandLine);
            while (tokenizer.hasMoreTokens())
                input.add(tokenizer.nextToken());
           
            ProcessBuilder pb = new ProcessBuilder(input);
            
            pb.directory(File);
            
            
       
            
            // now start the process
            BufferedReader br = null;
            try {
                           Process proc = pb.start();

                        // obtain the input and output streams
                        InputStream is = proc.getInputStream();
                        InputStreamReader isr = new InputStreamReader(is);
                        br = new BufferedReader(isr);

                // read what the process returned
                        String line;
                        while ( (line = br.readLine()) != null)
                                System.out.println(line);

                br.close();
            } catch (java.io.IOException ioe) {
                System.err.println("Error");
                System.err.println(ioe);
            }
            finally {
                if (br != null)
                    br.close();
            }
        }
    }
}

Please help! :)

[Norm]

I am having trouble

Can you explain your problem? Asking some specific questions would help.

[Asvin]

Oh, sorry for not being clear.. I want to add a history feature so that when the java program runs and the user types in the command for ubuntu in the terminal like "ls something", the program will show the history of all commands entered.. same goes with the commands to go to the home directory and change the directory to whatever the user types in!