pass enter key from Java to Shell script

Question

I am trying a Java program to run multiple commands in unix environment. I would need to pass 'ENTER' after each command. Is there some way to pass enter in the InputStream.

        JSch jsch=new JSch();
        Session session=jsch.getSession("MYUSERNAME", "SERVER", 22);
        session.setPassword("MYPASSWORD");
        Properties config = new Properties();
        config.put("StrictHostKeyChecking", "no");
        session.setConfig(config);
        session.connect();

        Channel channel= session.openChannel("shell");
        channel.setInputStream(getInputStream("ls -l"));
        channel.setInputStream(getInputStream("\r\n"));
        channel.setInputStream(getInputStream("pwd"));
        channel.setInputStream(getInputStream("\r\n"));
        channel.connect();

When I do ls -l, I want to add enter here, so that the command is executed. getInputStream is a method to convert String into InputStream.

Any help will be appreciated.

It just creates a new line into the command line. It does not do the enter. — Bhabani Shankar
– Bhabani Shankar, Commented Jun 23, 2015 at 14:35
You mean you want to send enter to the input of the shell? It isn't clear what you are asking. Try posting a (minimal) piece of code and explaining what is not working. — rghome
– rghome, Commented Jun 23, 2015 at 14:38
I have modified the question to add the program. it is currently \r\n, which is not working. It just is creating a new line — Bhabani Shankar
– Bhabani Shankar, Commented Jun 23, 2015 at 14:45

slim · Accepted Answer · 2015-06-23 14:59:56Z

According to the JSch javadoc, you must call setInputStream() or getOutputStream() before connect(). You can only do one of these, once.

For your purposes, getOutputStream() seems more appropriate. Once you have an OutputStream, you can wrap it in a PrintWriter to make sending commands easier.

Similarly you can use channel.getInputStream() to acquire an InputStream from which you can read results.

OutputStream os = channel.getOutputStream();
PrintWriter writer = new PrintWriter(os);
InputStream is = channel.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
channel.connect();
writer.println("ls -l");
String response = reader.readLine();
while(response != null) {
    // do something with response
    response = reader.readLine();
}
writer.println("pwd");

If you're determined to use setInputStream() instead of getOutputStream() then you can only do that once, so you'll have to put all your lines into one String:

    channel.setInputStream(getInputStream("ls -l\npwd\n"));

(I don't think you need \r, but add it back in if necessary)

If you're not familiar with working with streams, writers and readers, do some study on these before working with JSch.

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