"Stephenson,_Neal_-_In_the_Beginning_was_the_Command_Line" - читать интересную книгу автора (Stephenson Neal)

This is not the place to try to explain why each of the above directories exists, and what is contained in it. At first it all seems obscure; worse, it seems deliberately obscure. When I started using Linux I was accustomed to being able to create directories wherever I wanted and to give them whatever names struck my fancy. Under Unix you are free to do that, of course (you are free to do anything) but as you gain experience with the system you come to understand that the directories listed above were created for the best of reasons and that your life will be much easier if you follow along (within /home, by the way, you have pretty much unlimited freedom).

After this kind of thing has happened several hundred or thousand times, the hacker understands why Unix is the way it is, and agrees that it wouldn't be the same any other way. It is this sort of acculturation that gives Unix hackers their confidence in the system, and the attitude of calm, unshakable, annoying superiority captured in the Dilbert cartoon. Windows 95 and MacOS are products, contrived by engineers in the service of specific companies. Unix, by contrast, is not so much a product as it is a painstakingly compiled oral history of the hacker subculture. It is our Gilgamesh epic.

What made old epics like Gilgamesh so powerful and so long-lived was that they were living bodies of narrative that many people knew by heart, and told over and over again--making their own personal embellishments whenever it struck their fancy. The bad embellishments were shouted down, the good ones picked up by others, polished, improved, and, over time, incorporated into the story. Likewise, Unix is known, loved, and understood by so many hackers that it can be re-created from scratch whenever someone needs it. This is very difficult to understand for people who are accustomed to thinking of OSes as things that absolutely have to be bought.

Many hackers have launched more or less successful re-implementations of the Unix ideal. Each one brings in new embellishments. Some of them die out quickly, some are merged with similar, parallel innovations created by different hackers attacking the same problem, others still are embraced, and adopted into the epic. Thus Unix has slowly accreted around a simple kernel and acquired a kind of complexity and asymmetry about it that is organic, like the roots of a tree, or the branchings of a coronary artery. Understanding it is more like anatomy than physics.

For at least a year, prior to my adoption of Linux, I had been hearing about it. Credible, well-informed people kept telling me that a bunch of hackers had got together an implentation of Unix that could be downloaded, free of charge, from the Internet. For a long time I could not bring myself to take the notion seriously. It was like hearing rumors that a group of model rocket enthusiasts had created a completely functional Saturn V by exchanging blueprints on the Net and mailing valves and flanges to each other.

But it's true. Credit for Linux generally goes to its human namesake, one Linus Torvalds, a Finn who got the whole thing rolling in 1991 when he used some of the GNU tools to write the beginnings of a Unix kernel that could run on PC-compatible hardware. And indeed Torvalds deserves all the credit he has ever gotten, and a whole lot more. But he could not have made it happen by himself, any more than Richard Stallman could have. To write code at all, Torvalds had to have cheap but powerful development tools, and these he got from Stallman's GNU project.

And he had to have cheap hardware on which to write that code. Cheap hardware is a much harder thing to arrange than cheap software; a single person (Stallman) can write software and put it up on the Net for free, but in order to make hardware it's necessary to have a whole industrial infrastructure, which is not cheap by any stretch of the imagination. Really the only way to make hardware cheap is to punch out an incredible number of copies of it, so that the unit cost eventually drops. For reasons already explained, Apple had no desire to see the cost of hardware drop. The only reason Torvalds had cheap hardware was Microsoft.

Microsoft refused to go into the hardware business, insisted on making its software run on hardware that anyone could build, and thereby created the market conditions that allowed hardware prices to plummet. In trying to understand the Linux phenomenon, then, we have to look not to a single innovator but to a sort of bizarre Trinity: Linus Torvalds, Richard Stallman, and Bill Gates. Take away any of these three and Linux would not exist.


OS SHOCK


Young Americans who leave their great big homogeneous country and visit some other part of the world typically go through several stages of culture shock: first, dumb wide-eyed astonishment. Then a tentative engagement with the new country's manners, cuisine, public transit systems and toilets, leading to a brief period of fatuous confidence that they are instant experts on the new country. As the visit wears on, homesickness begins to set in, and the traveler begins to appreciate, for the first time, how much he or she took for granted at home. At the same time it begins to seem obvious that many of one's own cultures and traditions are essentially arbitrary, and could have been different; driving on the right side of the road, for example. When the traveler returns home and takes stock of the experience, he or she may have learned a good deal more about America than about the country they went to visit.

For the same reasons, Linux is worth trying. It is a strange country indeed, but you don't have to live there; a brief sojourn suffices to give some flavor of the place and--more importantly--to lay bare everything that is taken for granted, and all that could have been done differently, under Windows or MacOS.

You can't try it unless you install it. With any other OS, installing it would be a straightforward transaction: in exchange for money, some company would give you a CD-ROM, and you would be on your way. But a lot is subsumed in that kind of transaction, and has to be gone through and picked apart.

We like plain dealings and straightforward transactions in America. If you go to Egypt and, say, take a taxi somewhere, you become a part of the taxi driver's life; he refuses to take your money because it would demean your friendship, he follows you around town, and weeps hot tears when you get in some other guy's taxi. You end up meeting his kids at some point, and have to devote all sort of ingenuity to finding some way to compensate him without insulting his honor. It is exhausting. Sometimes you just want a simple Manhattan-style taxi ride.

But in order to have an American-style setup, where you can just go out and hail a taxi and be on your way, there must exist a whole hidden apparatus of medallions, inspectors, commissions, and so forth--which is fine as long as taxis are cheap and you can always get one. When the system fails to work in some way, it is mysterious and infuriating and turns otherwise reasonable people into conspiracy theorists. But when the Egyptian system breaks down, it breaks down transparently. You can't get a taxi, but your driver's nephew will show up, on foot, to explain the problem and apologize.

Microsoft and Apple do things the Manhattan way, with vast complexity hidden behind a wall of interface. Linux does things the Egypt way, with vast complexity strewn about all over the landscape. If you've just flown in from Manhattan, your first impulse will be to throw up your hands and say "For crying out loud! Will you people get a grip on yourselves!?" But this does not make friends in Linux-land any better than it would in Egypt.

You can suck Linux right out of the air, as it were, by downloading the right files and putting them in the right places, but there probably are not more than a few hundred people in the world who could create a functioning Linux system in that way. What you really need is a distribution of Linux, which means a prepackaged set of files. But distributions are a separate thing from Linux per se.

Linux per se is not a specific set of ones and zeroes, but a self-organizing Net subculture. The end result of its collective lucubrations is a vast body of source code, almost all written in C (the dominant computer programming language). "Source code" just means a computer program as typed in and edited by some hacker. If it's in C, the file name will probably have .c or .cpp on the end of it, depending on which dialect was used; if it's in some other language it will have some other suffix. Frequently these sorts of files can be found in a directory with the name /src which is the hacker's Hebraic abbreviation of "source."

Source files are useless to your computer, and of little interest to most users, but they are of gigantic cultural and political significance, because Microsoft and Apple keep them secret while Linux makes them public. They are the family jewels. They are the sort of thing that in Hollywood thrillers is used as a McGuffin: the plutonium bomb core, the top-secret blueprints, the suitcase of bearer bonds, the reel of microfilm. If the source files for Windows or MacOS were made public on the Net, then those OSes would become free, like Linux--only not as good, because no one would be around to fix bugs and answer questions. Linux is "open source" software meaning, simply, that anyone can get copies of its source code files.

Your computer doesn't want source code any more than you do; it wants object code. Object code files typically have the suffix .o and are unreadable all but a few, highly strange humans, because they consist of ones and zeroes. Accordingly, this sort of file commonly shows up in a directory with the name /bin, for "binary."

Source files are simply ASCII text files. ASCII denotes a particular way of encoding letters into bit patterns. In an ASCII file, each character has eight bits all to itself. This creates a potential "alphabet" of 256 distinct characters, in that eight binary digits can form that many unique patterns. In practice, of course, we tend to limit ourselves to the familiar letters and digits. The bit-patterns used to represent those letters and digits are the same ones that were physically punched into the paper tape by my high school teletype, which in turn were the same one used by the telegraph industry for decades previously. ASCII text files, in other words, are telegrams, and as such they have no typographical frills. But for the same reason they are eternal, because the code never changes, and universal, because every text editing and word processing software ever written knows about this code.

Therefore just about any software can be used to create, edit, and read source code files. Object code files, then, are created from these source files by a piece of software called a compiler, and forged into a working application by another piece of software called a linker.

The triad of editor, compiler, and linker, taken together, form the core of a software development system. Now, it is possible to spend a lot of money on shrink-wrapped development systems with lovely graphical user interfaces and various ergonomic enhancements. In some cases it might even be a good and reasonable way to spend money. But on this side of the road, as it were, the very best software is usually the free stuff. Editor, compiler and linker are to hackers what ponies, stirrups, and archery sets were to the Mongols. Hackers live in the saddle, and hack on their own tools even while they are using them to create new applications. It is quite inconceivable that superior hacking tools could have been created from a blank sheet of paper by product engineers. Even if they are the brightest engineers in the world they are simply outnumbered.

In the GNU/Linux world there are two major text editing programs: the minimalist vi (known in some implementations as elvis) and the maximalist emacs. I use emacs, which might be thought of as a thermonuclear word processor. It was created by Richard Stallman; enough said. It is written in Lisp, which is the only computer language that is beautiful. It is colossal, and yet it only edits straight ASCII text files, which is to say, no fonts, no boldface, no underlining. In other words, the engineer-hours that, in the case of Microsoft Word, were devoted to features like mail merge, and the ability to embed feature-length motion pictures in corporate memoranda, were, in the case of emacs, focused with maniacal intensity on the deceptively simple-seeming problem of editing text. If you are a professional writer--i.e., if someone else is getting paid to worry about how your words are formatted and printed--emacs outshines all other editing software in approximately the same way that the noonday sun does the stars. It is not just bigger and brighter; it simply makes everything else vanish. For page layout and printing you can use TeX: a vast corpus of typesetting lore written in C and also available on the Net for free.

I could say a lot about emacs and TeX, but right now I am trying to tell a story about how to actually install Linux on your machine. The hard-core survivalist approach would be to download an editor like emacs, and the GNU Tools--the compiler and linker--which are polished and excellent to the same degree as emacs. Equipped with these, one would be able to start downloading ASCII source code files (/src) and compiling them into binary object code files (/bin) that would run on the machine. But in order to even arrive at this point--to get emacs running, for example--you have to have Linux actually up and running on your machine. And even a minimal Linux operating system requires thousands of binary files all acting in concert, and arranged and linked together just so.