How to execute interactive commands and read their

问题:

Currently I can use the JSch library to execute remote commands in a SSH session like this:

JSch jsch = new JSch();
Session session = jsch.getSession(username, host, 22);
session.setPassword(password);

Properties config = new Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);

session.connect();

ChannelExec channel = (ChannelExec) session.openChannel("exec");
BufferedReader in = new BufferedReader(new InputStreamReader(channel.getInputStream()));

channel.setCommand("ls -l");
channel.connect();

StringBuilder output = new StringBuilder();

String s = null;
while((s = in.readLine()) != null){
    output.append(s + "\n");
}

System.out.println(output);

The commands that returns the full value right away works fine, but some interactive commands (like "Docker run") returns values every second or so (for a couple of minutes), and the previous code only read the first value returned.

Is there any way to read the values as they are returned by the command?

---

EDIT

This is my code now:

public String executeCommand(String cmd) {
    try {
        Channel channel = session.openChannel("shell");

        OutputStream inputstream_for_the_channel = channel.getOutputStream();
        PrintStream commander = new PrintStream(inputstream_for_the_channel, true);

        channel.setOutputStream(System.out, true);

        channel.connect();

        commander.println(cmd);

        commander.close();

        do {
            Thread.sleep(1000);
        } while(!channel.isEOF());
    } catch(Exception e) {
        e.printStackTrace();
    }
    return null;
}

回答1:

The way the JSch getInputStream is implemented, its read seems to return -1 not only when the session/channel closes, but also when there's momentarily no input data.

Your should better use channel.isClosed() to test if session/channel closed. See examples/Sudo.java:

byte[] tmp=new byte[1024];
while(true){
  while(in.available()>0){
    int i=in.read(tmp, 0, 1024);
    if(i<0)break;
    System.out.print(new String(tmp, 0, i));
  }
  if(channel.isClosed()){
    System.out.println("exit-status: "+channel.getExitStatus());
    break;
  }
  try{Thread.sleep(1000);}catch(Exception ee){}
}

---

Your code with "shell" channel prints the output on console, because you have instructed it so by:

channel.setOutputStream(System.out, true);

You have to implement the output stream to write to a string. See Get an OutputStream into a String

Or actually, you should be able to use the same code as with the "exec" channel.