Spawning a new process

In this recipe, we will see how to spawn a new process using ProcessBuilder. We will also see how to make use of the input, output, and error streams. This should be a very straightforward and common recipe. However, the aim of introducing this is to make this chapter a bit more complete and not just to focus on Java 9 features.

 

Getting ready

There is a command in Linux called free, which shows the amount of RAM that is free and how much is being used by the system. It accepts an option, -m, to show the output in megabytes. So, just running free -m gives us the following output: 

We will be running the preceding code from within the Java program.

How to do it...

Follow these steps:

1. Create an instance of ProcessBuilder by providing the required command and its options: 

        ProcessBuilder pBuilder = new ProcessBuilder("free", "-m");

An alternative way to specify the command and options is as follows:

        pBuilder.command("free", "-m");

2. Set up the input and output streams...