OS Processes using Java ProcessBuilder

This tutorial serves as ProcessBuilder feature introduction. For some need, I was attempting to print OS environment variables using java. Generally we get that done using the versatile System class like System.getenv(); This is very old as you can see the method name itself is not as per java convention, available from JDK 1.0

Since JDK 1.5 we have got a class java.lang.ProcessBuilder which is used to create OS processes. This API is available from JDK 1.5 but key features like redirect are added in JDK 1.7. We can use this ProcessBuilder to get current thread’s environment variables as below

package com.javapapers.corejava;

import java.util.Map;

public class ProcessBuilderSample {

	public static void main(String args[]) {
		ProcessBuilder testProcess = new ProcessBuilder();
		Map environmentMap = testProcess.environment();
		System.out.println(environmentMap);

		// usual way
		System.out.println(System.getenv());

	}

}

This is not the sole purpose of this class. It helps to create and execute OS processes and also gives us lot of flexibility over the already available System class.


Following example demonstrates how we can execute a set of native OS commands and get output/error redirected to a file. We can pass the commands from a file as we have done in this sample or we can pass it at run-time.

package com.javapapers.corejava;

import java.io.File;
import java.io.IOException;

public class ProcessBuilderSample {

	public static void main(String args[]) throws IOException {

		ProcessBuilder dirProcess = new ProcessBuilder("cmd");
		File commands = new File("C:/process/commands.bat");
		File dirOut = new File("C:/process/out.txt");
		File dirErr = new File("C:/process/err.txt");

		dirProcess.redirectInput(commands);
		dirProcess.redirectOutput(dirOut);
		dirProcess.redirectError(dirErr);

		dirProcess.start();

	}
}

To run the above program,

create a folder name “process” in C:/ and create the three files.
In commands.bat, put the following commands or something you like,

chdir
dir
date /t
echo Hello World

remember to run on JDK 1.7 and you can see the output in out.txt

This Core Java tutorial was added on 16/09/2012.

Comments on "OS Processes using Java ProcessBuilder" Tutorial:

  1. SUNIL KUMAR says:

    Nice one as always :)

  2. Devendra says:

    Something new to me.

  3. ayan says:

    Joe, ROCKS!!!

  4. Jackson says:

    Good one..

  5. Anonymous says:

    Nice… thanks

  6. Anonymous says:

    Good one. Thanks.

  7. Meenakshi says:

    nice example….

  8. student Lukas says:

    I like your posts about java. Thanks from Slovakia (-;

  9. Sahil Pachauri says:

    Really its very…nice blog. Its provide a lot of new things in java.
    Thanks joe from sahil

  10. SUMA says:

    very nice

  11. Hualet says:

    Simple but Nice!Good job! :-)

  12. Leo says:

    Hi Joe,

    Is above program works in Linux environment?

  13. Anonymous says:

    It is very nice. It can be elaborated using examples.

  14. Anonymous says:

    Nice to know new updates. Very helpful. Thank you sir.

  15. Anonymous says:

    Thanks for the introducing new features. Can we have more posts regarding this topic. It will be very helpful to learn more about process builder.

  16. kamal says:

    Great work….Please keep it up..

  17. Rathod Alpesh says:

    hello sir,
    good stuff, I would like a software that monitors the user’s activity such as openning of files, copying, moving, deletion etc. How can i do it in Java?

  18. shyam says:

    hi..
    i got error in all these line..because these
    methods not lies in class..

    dirProcess.redirectInput(commands);
    dirProcess.redirectOutput(dirOut);
    dirProcess.redirectError(dirErr);
    what is solution..?

  19. Shpresim says:

    Very nice. Thanks from Albania!

  20. shams says:

    im developing one scheduling of jsp web application can you sugest me how to do that by the way i did one simple banking application ie at one time 4 to 5 user needs to be run on same pc please

  21. Naveen says:

    excellent..

  22. Mukta says:

    How to run java prorame using java

  23. Rajesh says:

    I did not see the redirectInput, redirectErr, redirectErr methods in java 1.5 docs. May be u need to check this again

Comments are closed for this "OS Processes using Java ProcessBuilder" tutorial.