running scripts through processbuilder

Question

I'm trying to run Python, Ruby, C, C++, and Java scripts from a java program, and Processbuilder was suggested to me as a good way to run the scripts. From what I understand, Processbuilder mostly runs native files (.exe on windows, etc.). However, I have heard a few things about running scripts (nonnative) files using Processbuilder. Unfortunately, everything I find on the subject is incredibly vague.

If someone could clarify a way to run nonnative scripts such as Python, Ruby, etc. I would be most grateful!

Answer 1

You can check the ProcessBuilder documentation over at Sunoracle, but basically, you can run the interpreter for the scripting language and pass the script you want to run to it.

For example, let's say you have a script in /home/myuser/py_script.py, and python is in /usr/bin/

class ProcessRunner
{
    public static void main(String [] args)
    {
        ProcessBuilder pb = new ProcessBuilder("/usr/bin/python", "/home/myuser/py_script.py");
        Process p = pb.start();
    }
}

An extremely basic example, you can get fancier with changing the working directory and change the environment.

You can also construct ProcessBuilder with a String array or a subtype of List<String>. The first item in the list should be the program/executable you want to run, and all the following items are arguments to the program.

String pbCommand[] = { "/usr/bin/python", "/home/myuser/py_script.py" };
ProcessBuilder pb = new ProcessBuilder(pbCommand);
Process p = pb.start();

Answer 2

To avoid having to manually enter the entire location of the script, which may also result in portability issues, here's what I did:

String pwd = System.getProperty("user.dir");

ProcessBuilder pb = new ProcessBuilder("/usr/bin/python", pwd+'/'+scriptName, arg1, arg2);
Process p = pb.start();