Running Linux, 5th Edition - Matthias Kalle Dalheimer [421]
When reading about the Java applets, you might have thought, "And what happens if the applet contains mischievous code that spies on my hard disk or even maybe deletes or corrupts files?" Of course, this would be possible if the Java designers had not designed a multistep countermeasure against such attacks: all Java applets run in a so-called sandbox, which allows them access only to certain resources. For example, Java applets can output text on your monitor, but they can't read data from your local filesystem or even write to it unless you explicitly allow them. Although this sandbox paradigm reduces the usefulness of applets, it increases the security of your data. With recent Java releases, you can determine how much security you need and thus have additional flexibility. It should be mentioned that there have been reports of serious security breaches in the use of Java in browsers, although at least all known ones are found and fixed in most current web browsers.
If you decide that Java is something for you, we recommend that you get a copy of Thinking in Java (Prentice Hall). It covers most of the things you need to know in the Java world and also teaches you general programming principles. Other Java titles that are well worth looking into include Learning Java (O'Reilly) and Core Java (Prentice Hall).
Getting Java for Linux
Fortunately, there is a Linux port of the so-called JDK, the Java Developers Kit provided by Sun Microsystems for Solaris and Windows that serves as a reference implementation of Java. In the past, there was usually a gap between the appearance of a new JDK version for Solaris and Windows and the availability of the JDK for Linux. Luckily, this is no longer the case.
The "official" Java implementation JDK contains a compiler, an interpreter, and several related tools. Other kits are also available for Linux, often in the form of open source software. We cover the JDK here, though, because that's the standard. There are other Linux implementations, including a very good one from IBM, as well; you might even have them on your distribution CDs.
One more note: most distributions already contain the JDK for Linux, so it might be easier for you to simply install a prepackaged one. However, the JDK is moving fast, and you might want to install a newer version than the one your distribution contains.
Your one-stop shop for Java software (including environments for Linux) is http://java.sun.com. Here, you will find documentation and news, and of course you can download a copy of the JDK for your machine.
After unpacking and installing the JDK according to the instructions, you have several new programs at your disposal. javac is the Java compiler, java is the interpreter, and appletviewer is a small GUI program that lets you run applets without using a full-blown web browser.
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[*] One of the authors does all his financial business with his bank via a Java applet that his bank provides when browsing a special area of its web server.
Python
Python has gained a lot of attention lately because it is a powerful mixture of different programming paradigms and styles. For example, it is one of the very few interpreted object-oriented programming languages (Perl being another example, but only relatively late in its existence). Python fans say it is especially easy to learn. Python was written and designed almost entirely by Guido van Rossum, who chose the name because he wrote the interpreter while watching reruns of the British TV show Monty Python's Flying Circus. The language is introduced in Learning Python and covered in detail in Programming Python (both published by O'Reilly).
As nice and useful as Perl is, it has one disadvantage—or at least many people think so—namely, that you can write the same code in many different ways. This has given Perl the reputation that it's easy to write code in Perl, but hard to read it. (The point is that another programmer might do things differently from you, and you might therefore not be used to reading that style.) This means