There are more than a dozen other Java commands (tools and utilities) that you will only start using probably after several years of professional programming, if at all. They are all described in the Oracle Java documentation online. Just search the Java utilities and tools.
Among them, we find only one command that is very useful from day one of Java programming. It is the command jcmd. If you run it, it displays all of the Java processes (JVM instances) that are running on your computer. In this example, you can see three Java processes, with the process IDs 3408, 3458, and 3454:
Process 3408 runs the Maven server (your IDE will typically start it). Process 3458 is our running of jcmd. And process 3454 is an editor (IDE) IntelliJ IDEA that is running the small demo application com.packt.javapath.App.
This way, you can always check to see if there is a runaway Java process on your computer. If you would like to stop it, you can use a Task Manager, or the command kill, which requires PID.
Knowledge of PID is also needed when you would like to monitor your Java application. We will talk about that in Chapter 11, JVM Processes and Garbage Collection.
With this, we complete our overview of Java commands. As we already mentioned, your IDE will use all of these commands behind the scenes, so you will probably never use them unless you do production support (which is several years out, after you start learning Java). But we feel that you need to know them, so that you can connect the dots of the Java development process.