LinuxQuestions.org - Scripting with pipes and Java

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Scripting with pipes and Java

I have a directory of folders, each containing a number of .class (Java) files. I would like to write a script to run each one and test it on a number of given inputs.
In otherwords, when I normally type "java myClass" in one of the folders, a console menu will appear and ask for some input. I might choose option "1" and hit enter; then it will ask me, say, what my name is - I'll type in my name, and it will bring the menu back up; and so on and so forth.
I can probably figure out how to traverse all the folders (I just began scripting today), but I can't seem to figure out how to run the test cases on the java files. I tried scripts as simple as these:

Code:

echo -e "1\nBlueRaja" | java myClass

Code:

(echo 1; echo BlueRaja) | java myClass

and more complex code (using a named pipe) like this:

Code:

#!/bin/csh

mkfifo pipe

java myClass <pipe >output.out &

echo -e "a\n" > pipe

echo -e "BlueRaja\n" > pipe



exit 0

However, nothing seems to work. If anyone could lend me some of their insight, it would be greatly appreciated.

Thank you.

The Java program reads input using the following code, if this helps:

Code:

InputStreamReader inStream = new InputStreamReader(System.in);

BufferedReader    stdin    = new BufferedReader(inStream);

String            input    = stdin.readLine();

hi,
try test.sh

Code:

java myClass <<DELIMITER

7

DELIMITER

replace 7 by whatever you want to enter if the program were running interactively.

bye,
mustafa

both of these work:

Code:

echo 1 | java myClass

Code:

java myClass <<DELIMITER

1

DELIMITER

However, I would like to input more than one thing after another using a script - the following does not work:

Code:

java myClass <<DELIMITER

1

BlueRaja

DELIMITER

Also: According to everything I've read, this should work:

Code:

input.txt:

1

BlueRaja

Code:

user% java myClass < input.txt

This works in Windows, but not Linux (in two separate Linux machines) - I've tried everything I can think of, and am just about to give up with Linux and just do it in a batch file...

The problem must be in your java code, I believe the first bufferedReader is flushed somewhere there.

A simple Java program using your sample code works fine under Unix:

Code:

import java.io.*;



public class Test

{

  public static void main(String args[]) throws Exception

  {

    try

    {

      InputStreamReader inStream = new InputStreamReader(System.in);

      BufferedReader    stdin    = new BufferedReader(inStream);

      String            input    = stdin.readLine();

      System.out.println("input="+input);

      input    = stdin.readLine();

      System.out.println("input="+input);

    }

    catch(Exception e)

    {

      throw(e);

    }

  }

}



- = - = - = - = -



$ java Test <<%EOF%

one

two

%EOF%

input=one

input=two

$

Wait...I'm *not* supposed to flush the BufferedReader? o_O
Wow thanks, I think I can get it working now... but why does flushing BufferedReader screw it up?

Because you discard the remaining lines before giving a chance your application to read them.