An example using jSch exec channel

[mhndev]

Hi,
I need to execute a single command on a remote linux server which asks multiple questions.
Can you please give me an example ? how should I feed answers ?

[oopsaleem]

Hi @mhndev

        JSch jSch;
        StringBuilder remarks = new StringBuilder();
        StringBuilder error = new StringBuilder();
        StringBuilder rawData = new StringBuilder();
        try {
            Properties properties = new Properties();
            properties.put("PreferredAuthentications", "publickey,keyboard-interactive,password");
            properties.put("StrictHostKeyChecking", "no");
            properties.put("UseDNS", "no");
            jSch = new JSch();
            Session session = jSch.getSession("user", "ip", 22);
            session.setConfig(properties);
            session.setTimeout(15 * 1_000);
            session.setPassword("password");
            session.connect();
            Channel channel = session.openChannel("shell");
            channel.connect();
            try (Expect expect = new ExpectBuilder()
                .withTimeout(10, TimeUnit.SECONDS)
                .withOutput(channel.getOutputStream())
                .withInputs(channel.getInputStream(), channel.getExtInputStream())
                .withEchoInput(rawData)
                .withEchoOutput(error)
                .withInputFilters(removeColors(), removeNonPrintable())
                .withExceptionOnFailure()
                .build()) {
                Result multiResult = expect.expect(sequence(regexp(".+"), regexp(">.|>|<.|<|#.|#|$.|$")));
                String input = multiResult.getInput();
                if (input.contains("assword:")) {
                    remarks.append("Invalid username or password.");
                } else {
                    try {
                       // execute command
                        expect.sendLine("command-making-question");
                       // expect question
                        multiResult = expect.expect(sequence(regexp(".+"), regexp("want to continue\(Yes\/No\)\?")));
                       // collect the output
                        input = multiResult.getInput(); 

                       // send answer
                        expect.sendLine("yes");
                       // expect prompt
                        multiResult = expect.expect(sequence(regexp(".+"), regexp(">.|>|<.|<|#.|#|$.|$")));
                       // collect the output
                        input = multiResult.getInput(); 
                    } catch (Exception ex) {
                        error.append(String.format("Error with [%s]: %s. %s", command, ex.getMessage(), ex.getCause() == null ? "" : "Cause: " + ex.getCause()));
                    }
                }
            } finally {
                channel.disconnect();
                session.disconnect();
            }
            if (rawData.length() <= 0 )
                  return new CommandWrapper(remarks.toString(), error.toString());
            else 
                  return new CommandWrapper(rawData.toString());
        } catch (Exception e) {
            return new CommandWrapper(remarks.toString(), String.format("Error: %s %s %s",
                e.getMessage(),
                e.getCause() == null ? "" : "Cause: " + e.getCause(),
                error.toString()));
        }