Building a Terminal Emulator for Android

I've been trying to build a Terminal Emulator for Android. Being pretty new to this, my idea was to execute each command and store the output in a file, whose contents would be displayed after each execution. Pseudo Code :

public Boolean execCommands(String command) {
        try {
            rt = Runtime.getRuntime();
            process = rt.exec("su");
            DataOutputStream os = new DataOutputStream(process.getOutputStream());
            os.writeBytes("echo $ \""+command+ "\" >> /sdcard/Android/data/terminalemulatorlog.txt\n\n\n"); 
            /**** Note :  String command = (EditText)findViewById(R.id.command).getText().toString(); ****/
            os.flush();
            os.writeBytes("exit\n");
            os.flush();
            process.waitFor();
            }
        // Error Handling
        displayOutput(); //Loads and displays the Text File (/sdcard/Android/data/terminalemulatorlog.txt)
        return true;
        }

This piece of code works except for a few special commands (Eg. 'clear'). But what I'm more concerned about are the following problems :

Each time a command is to be executed, I end up seeking SuperUser permissions (second line of code). And I'd like to do away with this.
In cases when the user enters one command followed by another,
Such as :
```
cd /sdcard    
touch File.txt    
```
The File.txt is created in '/' and not in '/sdcard'. As of now to avoid this, I'm keeping a track of all the 'cd' commands to figure out what the present working directory is. And I'm hoping that there is a better way around this.

I'd be grateful if someone could help me out here.

Solution

Not sure if you are still needing this or not, but here is how I am issuing multiple commands at one time and not using "su" to have them run.

try {
    String[] commands = {           
            "dumpstate > /sdcard/LogFiles/dumpstate.txt",
            "dumpsys > /sdcard/LogFiles/dumpsys.txt",
            "logcat -d > /sdcard/LogFiles/log.txt",
            "cat /sdcard/LogFiles/dumpstate.txt /sdcard/LogFiles/dumpsys.txt /sdcard/LogFiles/log.txt > /sdcard/LogFiles/bugreport.rtf" };
    Process p = Runtime.getRuntime().exec("/system/bin/sh -");
    DataOutputStream os = new DataOutputStream(p.getOutputStream());
    for (String tmpCmd : commands) {
        os.writeBytes(tmpCmd + "\n");
    }
} catch (IOException e) {
    e.printStackTrace();
}