ssh in java (run commands on another machine)

Question

I was wondering whether there was a simple way to do this as part of a java program.

I would like to be able to ssh into another machine and perform commands on that machine.

A simple example would be: runtime.exec("say hello world"); would (on a mac) have a text-to-speech engine speak hello world.

Is there a way to have java run this method on another machine?

Also, assuming the above is possible, is there a way to ssh into more than one machine at the same time?

Thanks

Answer 1

There are a lot of libraries to do this. I suggest Ganymed SSH-2, that is also mentioned in the official OpenSSH website. In the same site, you can also find other libraries that you can use for Java.

This is an example of ls -r command executed via SSH, using Ganymed SSH-2:

import ch.ethz.ssh2.Connection;
import ch.ethz.ssh2.Session;
import ch.ethz.ssh2.StreamGobbler;

[...]

public static ArrayList<String> lsViaSSH(String hostname, String username, String password, String dir) {
    ArrayList<String> ls = new ArrayList<String>();

    try
    {
        Connection conn = new Connection(hostname);

        conn.connect();

        boolean isAuthenticated = conn.authenticateWithPassword(username, password);

        if (isAuthenticated == false) {
            return null;
        }

        Session sess = conn.openSession();

        sess.execCommand("ls -r " + dir);

        InputStream stdout = new StreamGobbler(sess.getStdout());

        BufferedReader br = new BufferedReader(new InputStreamReader(stdout));

        while (true)
        {
            String line = br.readLine();
            if (line == null)
                break;
            ls.add(line);
        }

        sess.close();
        conn.close();
    }
    catch (IOException e)
    {
        return null;
    }

    if(StringUtils.isEmpty(ls.get(0)))
        return null;

    return ls;
}

This is not the only function needed in order to execute a command via SSH, but I hope it could be a good starting point for you.