How to Create an Executable Zip File

Python has the ability to execute a zip file that contains Python files. This makes it very handy to create an executable zip file. Here's an example how to do it.

test.py

#!/usr/bin/env python

def say_something(): print "Hello World"
def main(): say_something()

__main__.py

#!/usr/bin/env python

import test

if __name__ == "__main__": test.main()

The __main__.py must be in the root directory of the zip file.

Zip all the Python files so that it looks like below. We don't need to use .zip extension, we can name it anything we want.

test.zip
|-- __main__.py
`-- test.py

To execute it:

python test.zip

and you will see the output as

Hello World

How to Capture StdOut/StdErr in Java

package test;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.io.PrintStream;
import java.io.StringWriter;

public class Main {
    public static interface Function {
        void execute();
    }
    
    public static String capture1(PrintStream ps, Function func)
        throws IOException {
        PipedOutputStream pos = new PipedOutputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(
            new PipedInputStream(pos)));
        StringWriter sw = new StringWriter();
        String output = null;
        try {
            PrintStream old = ps;
            System.setOut(new PrintStream(pos));

            func.execute();
            System.out.flush();

            pos.close();

            System.setOut(old);

            int charsRead;
            char[] cbuf = new char[4096];
            while ((charsRead = br.read(cbuf, 0, cbuf.length)) != -1) {
                sw.write(cbuf, 0, charsRead);
            }
            output = sw.toString();
        }
        finally {
            br.close();
            sw.close();
        }
        return output;
    }
    
    public static String capture2(PrintStream ps, Function func)
        throws IOException {
        String output = null;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
            PrintStream old = System.out;
            System.setOut(new PrintStream(baos));

            func.execute();
            System.out.flush();

            System.setOut(old);

            output = baos.toString();
        }
        finally {
            baos.close();
        }
        return output;
    }
    
    public static void main(String[] args) throws Exception {
        String output = capture1(System.out, new Function() {
            @Override
            public void execute() {
                System.out.println("Hello World");
                System.out.println("Bye World");
            }
        });
        System.out.println(output);
        
        
        output = capture2(System.out, new Function() {
            @Override
            public void execute() {
                System.out.println("Hello World");
                System.out.println("Bye World");
            }
        });
        System.out.println(output);
    }
}