Question

I am using java ssh tools to make an ssh connection to my school account and look for a file and then delete it. However I am creating three functions to do the same thing but with different files, I am looking for a way to do that at the same thing instead of doing one after the other. Here is some code. Basically I want to know if there is a way to do this all on one ssh connection or some kind of fork or multithreading.

public void updateinterval() {
    try {
        JSch jsch = new JSch();

        String user = "***********";
        String host = "********";
        Session session = jsch.getSession(user, host, 22);

        session.setPassword("*********");

        // username and password will be given via UserInfo interface.
        UserInfo userInfo = new SftpUserInfo();

        session.setUserInfo(userInfo);

        session.connect();

        // look for a file named feedinterval

        String checkfortimeupdate =
                "cd public_html/final;grep '-send' feedinterval";

        Channel channel = session.openChannel("exec");
        ((ChannelExec) channel).setCommand(checkfortimeupdate);

        // X Forwarding
        // channel.setXForwarding(true);

        // channel.setInputStream(System.in);
        channel.setInputStream(null);

        // channel.setOutputStream(System.out);

        // FileOutputStream fos=new FileOutputStream("/tmp/stderr");
        // ((ChannelExec)channel).setErrStream(fos);
        ((ChannelExec) channel).setErrStream(System.err);

        InputStream in = channel.getInputStream();

        channel.connect();

        byte[] tmp = new byte[1024];

        while (true) {
            while (in.available() > 0) {
                int i = in.read(tmp, 0, 1024);
                if (i < 0)
                    break;
                String returned = new String(tmp, 0, i);

                String argument = returned.substring(6);

                if (returned.contains("-send")) {

                    // if its there its calls the removeinterval function
                    // which removes the file it found
                    // by doing the same thing this function does but with a
                    // different ssh command

                    arduinoupdate hey = new arduinoupdate();

                    hey.removeinterval();

                    try {
                        Runtime rt = Runtime.getRuntime();

                        String[] commands = {
                                "system.exe", "-send", argument };

                        Process proc = rt.exec(commands);
                    }

                    catch (IOException e) {
                    }
                }
            }

            if (channel.isClosed()) {
                System.out.println("UpdateInterval Closed exit-status: "
                        + channel.getExitStatus());
                break;
            }
            try {
                /* Thread.sleep(1000); */
            } catch (Exception ee) {
            }
        }
        channel.disconnect();
        session.disconnect();
    } catch (Exception e) {
        System.out.println(e);
    }
}

Answer 1

If you want to run multiple tasks perhaps ExpectJ would work better for you. ExpectJ uses JSCH under the covers, so this may make your life easier.

final ExpectJ expectJ = new ExpectJ();
final Spawn spawn = expectJ.spawn("host", 22, "user", "pass");
spawn.send("cd public_html/final\n");
spawn.expect("someReturn");
...
spawn.send("exit\n");
spawn.expectClose();