Sending user input to console in Java

Question

I am trying to write something in Java to automatically import a certificate. When entering this command in the command shell:

    keytool -import -keystore c:\.truststore -alias xenv -file cacert.pem

it asks me for 2 questions: the password and if I want to confirm. In Python, I can use subprocess.Popen as follows:

p = subprocess.Popen("keytool","-import","-keystore","c:\\.truststore","-alias","xenv","-file","cacert.pem", stdin=subprocess.PIPE, stdout=subprocess.PIPE)
stdout, stderr = p.communicate("password\n" + "y\n")

I am now attempting to do something similar in Java. I think I'm on the right track after a few hours of playing around, but I can't quite get it to work. Any idea what I am doing wrong? Thanks in advance!

import java.io.*;

public class PropertyTest {

    public static void main(String[] args) throws IOException {
        ProcessBuilder pb = new ProcessBuilder("cmd", "/c", "keytool", "-import", "-keystore", "c:\\.truststore", "-alias", "xenv", "-file", "c:\\cacert.pem");
        pb.redirectErrorStream(true);
        Process p = pb.start();
        OutputStream out = p.getOutputStream();
        out.write("password\n".getBytes());
        out.write("y\n".getBytes());
    }
}

Why? You can provide the password as a parameter, and you can eliminate the confirmation prompt with another parameter. And you can eliminate the whole thing by using the KeyStore class. — user207421
– user207421, Commented Jul 10, 2014 at 0:37
In this simplified example you can pass in the password as a parameter, but there are a bunch of cases when using keytool or openssl that you must confirm things such as the organizational unit, etc. and you cannot pass those confirmations in as a parameter. — Trinculo
– Trinculo, Commented Jul 10, 2014 at 1:08
That is simply untrue. You can pass in everything as a parameter to the keytool, and you can also use the KeyStore API directly and avoid the whole problem. You're going about this quite the wrong way. — user207421
– user207421, Commented Jul 10, 2014 at 1:10
Ok, forget the keytool example. The question is on how to pass in user input in general using a similar manner to C and Python's pOpen. Do you know how? — Trinculo
– Trinculo, Commented Jul 10, 2014 at 2:14

Trinculo · Accepted Answer · 2014-07-10 07:51:35Z

1

This worked. I changed it to a BufferedWriter and flushed and closed it when I was done. Hopefully this helps someone else out who is stuck on a similar problem!

    ProcessBuilder pb = new ProcessBuilder("cmd", "/c", "keytool", "-import", "-keystore", "c:\\.truststore", "-alias", "alias", "-file", "c:\\cacert.pem");
    pb.redirectErrorStream(true);
    Process p = pb.start();
    BufferedWriter out = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
    out.write("allgoodthings\n");
    out.write("y\n");
    out.flush();
    out.close();

answered Jul 10, 2014 at 7:51

Trinculo

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2 Comments

user207421 Over a year ago

You don't really need the BufferedWriter. The close may have helped, the flush almost certainly.

Trinculo Over a year ago

You're right. I just tested with an OutputStream and it worked too. Removing the flush actually did nothing though (nothing visible at least), but it will not work without the close.

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