Jsch or SSHJ or Ganymed SSH-2?

1. I need to connect to server(username,pasw,host)-- easy

2. enter 3-10 commands -- command="dir;date;cd;dir" is there an easier way ?, without writing 20 lines: while(smtng) { a lot of stuff+ mysterious print to scr:D }

3. download a file-- easy

4. write another downloaded file to the same file (add not owerride) -- any ideas how?

So to perform these increadible easy tasks, which might seem impossible if you dare to use Jsch(awsome documentation), there is a choise between Jsch,sshj,Ganymed any suggestions?

Mystery:

2) multiple commands entering

4) adding to the existing txt file more txt :D (probably there is a build in command) or not?

  /* just for download/owerride : sftpChannel.get("downloadfile.txt", "savefile.txt");*/

I don't know about Ganymed. But I have used JSch extensively for remote login and script executions. I used Google's Expect4j with Jsch for executing scripts on remote machines in expect mode(send/wait). You can get the whole output of executed command or scripts in your code using JSch/Expect4j/Closures.

For jsch, go to http://www.jcraft.com/jsch/
For Expect4j, go to http://code.google.com/p/expect4j/

The following is a small code sample for logging in and executing file for remote Java class.

private Expect4j SSH(String hostname, String username,String password, int port) throws Exception {
    JSch jsch = new JSch();
    Session session = jsch.getSession(username, hostname, port);
    if (password != null) {         
        session.setPassword(password);
    }
    Hashtable<String,String> config = new Hashtable<String,String>();
    config.put("StrictHostKeyChecking", "no");
    session.setConfig(config);
    session.connect(60000);
    channel = (ChannelShell) session.openChannel("shell");
    Expect4j expect = new Expect4j(channel.getInputStream(), channel.getOutputStream());
    channel.connect();      
    return expect;
}

This method will open up a SSH stream to the remote server which will be used by expect4j for sending commands.

private boolean executeCommands() {
        boolean isSuccess = true;
        Closure closure = new Closure() {
            public void run(ExpectState expectState) throws Exception {
                buffer.append(expectState.getBuffer());//buffer is string buffer for appending output of executed command             
                expectState.exp_continue();
            }
        };
        List<Match> lstPattern =  new ArrayList<Match>();
        String[] regEx = SSHConstants.linuxPromptRegEx;  
        if (regEx != null && regEx.length > 0) {
            synchronized (regEx) {
                for (String regexElement : regEx) {//list of regx like,  :>, /> etc. it is possible command prompts of your remote machine
                    try {
                        RegExpMatch mat = new RegExpMatch(regexElement, closure);
                        lstPattern.add(mat);                        
                    } catch (MalformedPatternException e) {                     
                        return false;
                    } catch(Exception e) {                      
                        return false;
                    }
                }
                lstPattern.add(new EofMatch( new Closure() { // should cause entire page to be collected
                    public void run(ExpectState state) {
                    }
                }));
                lstPattern.add(new TimeoutMatch(defaultTimeOut, new Closure() {
                    public void run(ExpectState state) {
                    }
                }));
            }
        }
        try {
            Expect4j expect = SSH(objConfig.getHostAddress(), objConfig.getUserName(), objConfig.getPassword(), SSHConstants.SSH_PORT);
            expect.setDefaultTimeout(defaultTimeOut);       
            if(isSuccess) {
                for(String strCmd : lstCmds)
                    isSuccess = isSuccess(lstPattern,strCmd);
            }
            boolean isFailed = checkResult(expect.expect(lstPattern));
            return !isFailed;
        } catch (Exception ex) {            
            return false;
        } finally {
            closeConnection();
        }
    }


private boolean isSuccess(List<Match> objPattern,String strCommandPattern) {
        try {   
            boolean isFailed = checkResult(expect.expect(objPattern));

            if (!isFailed) {
                expect.send(strCommandPattern);         
                expect.send("\r");              
                return true;
            } 
            return false;
        } catch (MalformedPatternException ex) {    
            return false;
        } catch (Exception ex) {
            return false;
        }
}  

I can't comment on the others but Ganymed works very well indeed.