The Barnes & Noble Review
Already know NT or Windows 2000? Want to understand how Linux might fit into your Windows network? Here's the real deal -- fair, objective, and practical -- from one of the world's leading Windows experts (Mark Minasi) and two of the world's leading Linux experts (Dan York and Craig Hunt).
Linux for Windows NT/2000 Administrators presents Linux's strengths and weaknesses from the Windows expert's point of view. You'll learn what's easy to integrate, where the value adds are, where Linux doesn't measure up to the hype, and more.
You'll walk through all the basic tasks you could probably do in Windows in your sleep, but may be clueless about handling in Linux: managing files, creating partitions, printing, dealing with comprssed files, backing up to tape, creating user accounts, and so forth. Next you'll start building servers -- all kinds of servers. DNS and DHCP servers, web servers, Sendmail e-mail servers, FTP servers, proxy servers, dial-in servers, even Ethernet-to-Ethernet IP routers. There's detailed coverage of interoperability: sharing data across Linux and Windows computers, and sharing network services -- including a chapter on Samba that hits on some significant real-world issues we just haven't seen covered anywhere else.
As Minasi observes, "Windows 9x, NT, 2000, and Linux have all dealt me too many troubles of various types at various times for me to get all dewy-eyed about any one of them. They're all decent tools, but imperfect ones, for their own reasons." If your career depends on choosing the right tools and using them the right away, that's the attitude you want to hear -- and this is the book you want to get. (Bill Camarda)
Bill Camarda is a consultant and writer with nearly 20 years' experience in helping technology companies deploy and market advanced software, computing, and networking products and services. His 15 books include Special Edition Using Word 2000 and Upgrading & Fixing Networks For Dummies®, Second Edition.
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Chapter 3: How the Linux World Operates
Most of the other operating systems you've ever worked with were probably the brainchild of someone or some group of people, all working for the same company. Those people all sought on behalf of that company to create a piece of software that was a commercial product. Building operating systems is time-consuming-forget "man-hours," operating systems consume person-millennia in their birth struggles. All of that time is expensive, which is one reason why big commercial concerns are the only entities that can afford to build a new OS.
Well, usually the only entities. With Linux, we have a huge operating system basically built as a volunteer effort. How did this happen? How is ongoing Linux development managed? Who "owns" Linux? And just how do all of these Linux proponents expect to make a living giving away software? In this chapter, we'll look at those questions.
The Birth and Evolution of Linux
What inspired Linus Torvalds to create Linux in the first place? As so often the case in hobbyist computer projects, he started out to put together a small project ... and it just grew.
AT&T Stops Giving Away Unix
The story starts in the late '60s. In 1969, a computer programmer named Ken Thompson at AT&T's Bell Labs (with Dennis Ritchie and many others) developed what eventually became Unix. AT&T was regulated and could not sell software at the time, so they basically gave away copies of Unix, source code and all, to whomever wanted it. In the early 1980s, the U.S. government broke up AT&T's monopoly and AT&T itself, leaving the remaining part of AT&T (which included Bell Labs) able to sell software. As Unix was pretty popular by then, AT&T management figured they'd cash in on Unix's popularity, charging thousands of dollars for what was once free in their 1983 edition of Unix, "Unix System V."
In addition to charging for the system, AT&T also forbade universities and colleges from using Unix source code as an example in operating systems classes. This was a devastating event, as many such classes depended on Unix. So a fellow named Andrew Tanenbaum decided to create a substitute. In 1987, Tanenbaum wrote an excellent text, called Operating Systems, about how OSes work. He wanted instructors to be able to use it as a teaching text, and he knew it would be helpful if students could experiment with some basic operating systems notions, but again, AT&T forbade doing that
with Unix source. So Tanenbaum wrote a "teaching" OS, a simple Unix-like OS built from scratchno AT&T code. As PCs are cheap, he built this teaching OS on a PC. Tanenbaum called his operating system "Minix" (pronounced "minn-icks") in recognition of its minimal nature.
Linus Plus Minix Equals Linux
Somewhere between 1989 and 1991, depending on which version of the story you read, a Finnish student named Linus Torvalds was studying operating systems and working with Minix. He decided to learn more about OSes by building his own version of Minix from scratch, and then to add functionality to it, eventually enhancing it to the point where his expanded Minix would be a useful PC operating system. Partway through the process, he decided that what he wanted to do with Minix would involve so much revamping of Minix that he would do just as well to start from scratch and build a whole new operating system from the ground up. As his name was Linus, he decided to name the new OS "Linux." Even though his name is pronounced "lee-nus," he decided to rhyme with Minix-so Linux is pronounced "linn-icks."
But no new operating system is of value unless it has applications. As a techie, Linus knew Unix, and he also knew that there were many, many applications-free applications-that ran under Unix. So he decided to build Linux with an identical programming interface to Unix. That meant that Linux would, once finished, let him download source code for any number of Unix programs, compile those programs, and run them on Linux, often with no changes at all to those programs, even though Linux wasn't Unix-so long as the programming interface that the applications rest upon is the same, then the applications have no idea that they're not running Unix. The name of this programming interface, by the way, is POSIX, and in fact NT is equipped with a POSIX interface, albeit not a complete one, which means that you could sometimes even get some of those free "Unix" programs to run on NT!
Once Linus got Linux up and running, he saw that he had done a pretty cool thing, a from-theground-up clone of Unix. It lacked some major pieces, including networking and graphics, but it was a basically sound, PC-based operating system that could exploit all of the memory on a 386-based system and that could multitask programs in a pretty stable fashion. But even that wasn't the most impressive part of what Linus did.
Understanding Open Source: Linux's "Price"
Here's the impressive part of what Torvalds did: he decided to basically give Linux away, but with a few very significant strings attached. He decided not to charge people to use it, and to let them copy it to their heart's content. But he didn't put it in the public domain. Instead, he retained the ownership of Linux so that he could control how people copied Linux. Linus lets you use Linux only subject to a license that basically says
This license is a modification of the standard copyright provisions, so Linuxers, inveterate punsters that they are, often refer to this license as a "copyleft." (Get it? copyright...copyleft? Bet these guys are a laff riot at parties.)
- You are free to copy Linux as much as you want.
- You are free to sell copies of Linux.
- You are free to modify Linux and redistribute it.
- You may not, however, restrict the abilities of others to copy, modify, or distribute your modified Linux. In other words, if you come up with some terrific "fix" to Linux that makes it run 100 times faster, then you're welcome to sell this amazingly fast Linux, but you cannot forbid your customers from copying and giving away your amazingly fast Linux.
- When you distribute a copy of Linux, modified or not, then you must make the source code available. So once you come up with that amazingly fast Linux code, you can't just compile your Linux and give that away, retaining the secrets of how you made Linux faster. You must offer the source code as well-you must share your secrets.
Notice that this license applies to the operating system only, not to applications. Just because the Linux OS operates in what is called an "open source" fashion-"open source" meaning "you must make the source code available"-doesn't mean that applications for Linux must be open source. There's nothing stopping someone from offering a video driver for Linux without having to release the source code for the driver. There's nothing stopping Corel from creating a version of WordPerfect that runs on Linux, selling that version of WordPerfect, and not releasing the source code. Furthermore, many of the hundreds of free programs that come with Linux do not have a copyleft license. Some are public domain.
Linux, the Prequel: GPL and GNU
The particularly interesting thing about the modified copyright that Torvalds holds for Linux is what has been called the copyleft's "viral" nature. Sure, you can use Linux as a base for some other project. And the fact that it is an already-functioning operating system, that you can obtain its source code for no charge and use it as a launching pad for another OS product, are all very attractive points. But once you incorporate any Linux code into your product -one measly line of code-then you are bound by the copyleft to leave the source code of your resulting product open and accessible to the users of your product. In other words, make free use of this open source codebut if you do, you must open the source whatever you made with it....