How to execute a interactive shell script using java Runtime?

Question

I am wondering is there any way to execute following shell script, which waits for user input using java's Runtime class?

#!/bin/bash

echo "Please enter your name:"
read name
echo "Welcome $name"

I am using following java code to do this task but it just shows blank console.

public class TestShellScript {
public static void main(String[] args) {

        File wd = new File("/mnt/client/");
           System.out.println("Working Directory: " +wd);
           Process proc = null;

           try {
               proc = Runtime.getRuntime().exec("sudo ./test.sh", null, wd);

           } catch (Exception e) {
             e.printStackTrace();
             }


}

}

Thing is when I execute above program, I believed it will execute a shell script and that shell script will wait for user input, but it just prints current directory and then exits. Is there any way to do this or it is not possible at all in java?

Thanks in advance

Answer 1

The reason it prints the current dir and exits is because your java app exits. You need to add a (threaded) listener to the input and error streams of your created process, and you'll probably want to add a printStream to the process's output stream

example:

            proc = Runtime.getRuntime().exec(cmds);
            PrintStream pw = new PrintStream(proc.getOutputStream());
            FetcherListener fl = new FetcherListener() {

                @Override
                public void fetchedMore(byte[] buf, int start, int end) {
                    textOut.println(new String(buf, start, end - start));
                }

                @Override
                public void fetchedAll(byte[] buf) {
                }           
            };
            IOUtils.loadDataASync(proc.getInputStream(), fl);
            IOUtils.loadDataASync(proc.getErrorStream(), fl);
            String home = System.getProperty("user.home");
            //System.out.println("home: " + home);
            String profile = IOUtils.loadTextFile(new File(home + "/.profile"));
            pw.println(profile);
            pw.flush();

To run this, you will need to download my sourceforge project: http://tus.sourceforge.net/ but hopefully the code snippet is instructive enough that you can just adapt to J2SE and whatever else you are using.

Answer 2

If you use a Java ProcessBuilder you should be able to get the Input, Error and Output streams of the Process you create.

These streams can be used to get information coming out of the process (like prompts for input) but they can also be written to to put information into the process directly too. For instance:

InputStream stdout = process.getInputStream ();
BufferedReader reader = new BufferedReader (new InputStreamReader(stdout));

String line;
while(true){
    line = reader.readLine();
    //...

That'll get you the output from the process directly. I've not done it myself, but I'm pretty sure that process.getOutputStream() gives you something that can be written to directly to send input to the process.