Espacios propicios para el aprendizaje Uno de los grandes interrogantes del aprendizaje ¿cómo lograr establecer o definir cuál es el ambiente idóneo para cada

Linux is a bit of an oddball in the Unix operating system lineup. That’s because, unlike the Unix versions released by the major vendors, Linux did not reuse any existing source code. Instead, Linux was developed from scratch by a Finnish university student named Linus Torvalds. Most Popular Unix-Like OS

Linux was written from the start to function very simi- larly to existing Unix products. And because Torvalds worked on Linux as a hobby, with no intention of mak- ing money, it was distributed for free. These factors and others contributed to making Linux the most popular Unix operating system today.

Linux Is a Kernel

Strictly speaking, Torvalds ’ pet project has provided only one part of a fully functional Unix operating system: the kernel. The other parts of the operating system, includ- ing the commands, utilities, development environment, desktop environment, and other aspects of a full Unix

operating system, are provided by other parties, includ- ing GNU, XOrg, and others.

Linux Is a Community

Perhaps the most fundamentally different thing about Linux is the process by which it is developed and improved. As the hobby project that it was, Linux was released by Torvalds on the Internet in the hopes that someone out there might find it interesting. A few programmers saw Torvalds ’ hobby kernel and began working on it for fun, adding features and fleshing out functionality in a sort of unofficial partnership with Torvald. At this point, everyone was just having fun, tinkering with interesting concepts. As more and more people joined the unofficial club, Torvalds ’ pet project ballooned into a worldwide phenomenon.

Today, Linux is developed and maintained by hun- dreds of thousands of contributors all over the world. In 1996, Eric S. Raymond 3 famously described the dis- tributed development methodology used by Linux as a bazaar — a wild, uproarious collection of people, each developing whatever feature they most wanted in an operating system, or improving whatever shortcoming most impacted them; yet somehow, this quick-moving community resulted in a development process that was stable as a whole, and that produced an amazing amount of progress in a very short time.

This is radically different from the way in which Unix systems have typically been developed. If the Linux community is like a bazaar, then other Unix sys- tems can be described as a cathedral — carefully pre- planned and painstakingly assembled over a long period of time, according to specifications handed down by master architects from previous generations. Recently, however, some of the traditional Unix vendors have started moving toward a more decentralized, bazaar-like development model similar in many ways to the Linux methodology.

Linux Is Distributions

The Open Source movement in general is very impor- tant to the success of Linux. Thanks to GNU, XOrg, and other open-source contributors, there was an almost com- plete Unix already available when the Linux kernel was released. Linux only filled in the final missing component

2 The Open Group, n.d., “The Single Unix Specifi cation”, retrieved September 22, 2008, from What Is Unix: www.unix.org/what_is_unix/ single_unix_specifi cation.html .

3 E. S. Raymond, September 11, 2000, “The Cathedral and the

Bazaar”, retrieved September 22, 2008, from Eric S. Raymond’s homep- age: www.catb.org/esr/writings/cathedral-bazaar/cathedral-bazaar/index. html .

Eliminating the Security

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eakness of Linux and UNIX Oper

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FIGURE 6.1 The simplified Unix family tree presents a timeline of some of today’s most successful Unix variants. 10

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of a no-cost, open source Unix. Because the majority of the other parts of the operating system came from the GNU project, Linux is also known as GNU/Linux.

To actually install and run Linux, it is necessary to collect all the other operating system components. Because of the interdependency of the operating system components — each component must be compatible with the others — it is important to gather the right versions of all these components. In the early days of Linux, this was quite a challenge!

Soon, however, someone gathered up a self-consistent set of components and made them all available from a central download location. The first such efforts include H. J. Lu’s “ boot/root ” floppies and MCC Interim Linux. These folks did not necessarily develop any of these components; they only redistributed them in a more con- venient package. Other people did the same, releasing new bundles called distributions whenever a major upgrade was available.

Some distributions touted the latest in hardware sup- port; others specialized in mathematics or graphics or another type of computing; still others built a distribu- tion that would provide the simplest or most attractive user experience. Over time, distributions have become more robust, offering important features such as package management, which allows a user to safely upgrade parts of the system without reinstalling everything else. Linux Standard Base

Today there are dozens of Linux distributions. Different flavors of distributions have evolved over the years. A primary distinguishing feature is the package manage- ment system. Some distributions are primarily volunteer community efforts; others are commercial offerings. See Figure 6.2 for a timeline of Linux development. 4

The explosion in the number of different Linux dis- tributions created a situation reminiscent of the Unix wars of previous decades. To address this issue, the Linux Standard Base was created to specify certain key standards of behavior for conforming Linux distribu- tions. Most major distributions comply with the Linux Standard Base specifications.