How Linux Works

Java

Although some application programmers love Java, Unix systems programmers avoid it, and you may not even need it on your system. However, you should still have an idea of how it works on a typical Linux system.

There are two kinds of Java compilers: native compilers for producing machine code for your system (like a C compiler), and bytecode compilers for use by a bytecode interpreter (usually called a virtual machine, even though it's more of an abstract machine). You will invariably encounter bytecode on Linux.

Bytecode files end in .class. The Java runtime environment (JRE) contains all of the programs you need to run Java bytecode. To run a bytecode file, use this command:

java file.class

You may also encounter bytecode files that end in ...