In the Beginning was the Command Line

by Neal Stephenson

About twenty years ago Jobs and Wozniak, the founders of Apple, came up with the very strange idea of selling information processing machines for use in the home. The business took off, and its founders made a lot of money and received the credit they deserved for being daring visionaries. But around the same time, Bill Gates and Paul Allen came up with an idea even stranger and more fantastical: selling computer operating systems. This was much weirder than the idea of Jobs and Wozniak. A computer at least had some sort of physical reality to it. It came in a box, you could open it up and plug it in and watch lights blink. An operating system had no tangible incarnation at all. It arrived on a disk, of course, but the disk was, in effect, nothing more than the box that the OS came in. The product itself was a very long string of ones and zeroes that, when properly installed and coddled, gave you the ability to manipulate other very long strings of ones and zeroes. Even those few who actually understood what a computer operating system was were apt to think of it as a fantastically arcane engineering prodigy, like a breeder reactor or a U-2 spy plane, and not something that could ever be (in the parlance of high-tech) "productized."

Yet now the company that Gates and Allen founded is selling operating systems like Gillette sells razor blades. New releases of operating systems are launched as if they were Hollywood blockbusters, with celebrity endorsements, talk show appearances, and world tours. The market for them is vast enough that people worry about whether it has been monopolized by one company. Even the least technically-minded people in our society now have at least a hazy idea of what operating systems do; what is more, they have strong opinions about their relative merits. It is commonly understood, even by technically unsophisticated computer users, that if you have a piece of software that works on your Macintosh, and you move it over onto a Windows machine, it will not run. That this would, in fact, be a laughable and idiotic mistake, like nailing horseshoes to the tires of a Buick.

A person who went into a coma before Microsoft was founded, and woke up now, could pick up this morning's New York Times and understand everything in it--almost:

Item: the richest man in the world made his fortune from-what? Railways? Shipping? Oil? No, operating systems. Item: the Department of Justice is tackling Microsoft's supposed OS monopoly with legal tools that were invented to restrain the power of Nineteenth-Century robber barons. Item: a woman friend of mine recently told me that she'd broken off a (hitherto) stimulating exchange of e-mail with a young man. At first he had seemed like such an intelligent and interesting guy, she said, but then "he started going all PC-versus-Mac on me."

What the hell is going on here? And does the operating system business have a future, or only a past? Here is my view, which is entirely subjective; but since I have spent a fair amount of time not only using, but programming, Macintoshes, Windows machines, Linux boxes and the BeOS, perhaps it is not so ill-informed as to be completely worthless. This is a subjective essay, more review than research paper, and so it might seem unfair or biased compared to the technical reviews you can find in PC magazines. But ever since the Mac came out, our operating systems have been based on metaphors, and anything with metaphors in it is fair game as far as I'm concerned.


Around the time that Jobs, Wozniak, Gates, and Allen were dreaming up these unlikely schemes, I was a teenager living in Ames, Iowa. One of my friends' dads had an old MGB sports car rusting away in his garage. Sometimes he would actually manage to get it running and then he would take us for a spin around the block, with a memorable look of wild youthful exhiliration on his face; to his worried passengers, he was a madman, stalling and backfiring around Ames, Iowa and eating the dust of rusty Gremlins and Pintos, but in his own mind he was Dustin Hoffman tooling across the Bay Bridge with the wind in his hair.

In retrospect, this was telling me two things about people's relationship to technology. One was that romance and image go a long way towards shaping their opinions. If you doubt it (and if you have a lot of spare time on your hands) just ask anyone who owns a Macintosh and who, on those grounds, imagines him- or herself to be a member of an oppressed minority group.

The other, somewhat subtler point, was that interface is very important. Sure, the MGB was a lousy car in almost every way that counted: balky, unreliable, underpowered. But it was fun to drive. It was responsive. Every pebble on the road was felt in the bones, every nuance in the pavement transmitted instantly to the driver's hands. He could listen to the engine and tell what was wrong with it. The steering responded immediately to commands from his hands. To us passengers it was a pointless exercise in going nowhere--about as interesting as peering over someone's shoulder while he punches numbers into a spreadsheet. But to the driver it was an experience. For a short time he was extending his body and his senses into a larger realm, and doing things that he couldn't do unassisted.

The analogy between cars and operating systems is not half bad, and so let me run with it for a moment, as a way of giving an executive summary of our situation today.

Imagine a crossroads where four competing auto dealerships are situated. One of them (Microsoft) is much, much bigger than the others. It started out years ago selling three-speed bicycles (MS-DOS); these were not perfect, but they worked, and when they broke you could easily fix them.

There was a competing bicycle dealership next door (Apple) that one day began selling motorized vehicles--expensive but attractively styled cars with their innards hermetically sealed, so that how they worked was something of a mystery.

The big dealership responded by rushing a moped upgrade kit (the original Windows) onto the market. This was a Rube Goldberg contraption that, when bolted onto a three-speed bicycle, enabled it to keep up, just barely, with Apple-cars. The users had to wear goggles and were always picking bugs out of their teeth while Apple owners sped along in hermetically sealed comfort, sneering out the windows. But the Micro-mopeds were cheap, and easy to fix compared with the Apple-cars, and their market share waxed.

Eventually the big dealership came out with a full-fledged car: a colossal station wagon (Windows 95). It had all the aesthetic appeal of a Soviet worker housing block, it leaked oil and blew gaskets, and it was an enormous success. A little later, they also came out with a hulking off-road vehicle intended for industrial users (Windows NT) which was no more beautiful than the station wagon, and only a little more reliable.

Since then there has been a lot of noise and shouting, but little has changed. The smaller dealership continues to sell sleek Euro-styled sedans and to spend a lot of money on advertising campaigns. They have had GOING OUT OF BUSINESS! signs taped up in their windows for so long that they have gotten all yellow and curly. The big one keeps making bigger and bigger station wagons and ORVs.

On the other side of the road are two competitors that have come along more recently.

One of them (Be, Inc.) is selling fully operational Batmobiles (the BeOS). They are more beautiful and stylish even than the Euro-sedans, better designed, more technologically advanced, and at least as reliable as anything else on the market--and yet cheaper than the others.

With one exception, that is: Linux, which is right next door, and which is not a business at all. It's a bunch of RVs, yurts, tepees, and geodesic domes set up in a field and organized by consensus. The people who live there are making tanks. These are not old-fashioned, cast-iron Soviet tanks; these are more like the M1 tanks of the U.S. Army, made of space-age materials and jammed with sophisticated technology from one end to the other. But they are better than Army tanks. They've been modified in such a way that they never, ever break down, are light and maneuverable enough to use on ordinary streets, and use no more fuel than a subcompact car. These tanks are being cranked out, on the spot, at a terrific pace, and a vast number of them are lined up along the edge of the road with keys in the ignition. Anyone who wants can simply climb into one and drive it away for free.

Customers come to this crossroads in throngs, day and night. Ninety percent of them go straight to the biggest dealership and buy station wagons or off-road vehicles. They do not even look at the other dealerships.

Of the remaining ten percent, most go and buy a sleek Euro-sedan, pausing only to turn up their noses at the philistines going to buy the station wagons and ORVs. If they even notice the people on the opposite side of the road, selling the cheaper, technically superior vehicles, these customers deride them cranks and half-wits.

The Batmobile outlet sells a few vehicles to the occasional car nut who wants a second vehicle to go with his station wagon, but seems to accept, at least for now, that it's a fringe player.

The group giving away the free tanks only stays alive because it is staffed by volunteers, who are lined up at the edge of the street with bullhorns, trying to draw customers' attention to this incredible situation. A typical conversation goes something like this:

Hacker with bullhorn: "Save your money! Accept one of our free tanks! It is invulnerable, and can drive across rocks and swamps at ninety miles an hour while getting a hundred miles to the gallon!"

Prospective station wagon buyer: "I know what you say is don't know how to maintain a tank!"

Bullhorn: "You don't know how to maintain a station wagon either!"

Buyer: "But this dealership has mechanics on staff. If something goes wrong with my station wagon, I can take a day off work, bring it here, and pay them to work on it while I sit in the waiting room for hours, listening to elevator music."

Bullhorn: "But if you accept one of our free tanks we will send volunteers to your house to fix it for free while you sleep!"

Buyer: "Stay away from my house, you freak!"

Bullhorn: "But..."

Buyer: "Can't you see that everyone is buying station wagons?"


The connection between cars, and ways of interacting with computers, wouldn't have occurred to me at the time I was being taken for rides in that MGB. I had signed up to take a computer programming class at Ames High School. After a few introductory lectures, we students were granted admission into a tiny room containing a teletype, a telephone, and an old-fashioned modem consisting of a metal box with a pair of rubber cups on the top (note: many readers, making their way through that last sentence, probably felt an initial pang of dread that this essay was about to turn into a tedious, codgerly reminiscence about how tough we had it back in the old days; rest assured that I am actually positioning my pieces on the chessboard, as it were, in preparation to make a point about truly hip and up-to-the minute topics like Open Source Software). The teletype was exactly the same sort of machine that had been used, for decades, to send and receive telegrams. It was basically a loud typewriter that could only produce UPPERCASE LETTERS. Mounted to one side of it was a smaller machine with a long reel of paper tape on it, and a clear plastic hopper underneath.

In order to connect this device (which was not a computer at all) to the Iowa State University mainframe across town, you would pick up the phone, dial the computer's number, listen for strange noises, and then slam the handset down into the rubber cups. If your aim was true, one would wrap its neoprene lips around the earpiece and the other around the mouthpiece, consummating a kind of informational soixante-neuf. The teletype would shudder as it was possessed by the spirit of the distant mainframe, and begin to hammer out cryptic messages. Since computer time was a scarce resource, we used a sort of batch processing technique. Before dialing the phone, we would turn on the tape puncher (a subsidiary machine bolted to the side of the teletype) and type in our programs. Each time we depressed a key, the teletype would bash out a letter on the paper in front of us, so we could read what we'd typed; but at the same time it would convert the letter into a set of eight binary digits, or bits, and punch a corresponding pattern of holes across the width of a paper tape. The tiny disks of paper knocked out of the tape would flutter down into the clear plastic hopper, which would slowly fill up what can only be described as actual bits. On the last day of the school year, the smartest kid in the class (not me) jumped out from behind his desk and flung several quarts of these bits over the head of our teacher, like confetti, as a sort of semi-affectionate practical joke. The image of this man sitting there, gripped in the opening stages of an atavistic fight-or-flight reaction, with millions of bits (megabytes) sifting down out of his hair and into his nostrils and mouth, his face gradually turning purple as he built up to an explosion, is the single most memorable scene from my formal education.

Anyway, it will have been obvious that my interaction with the computer was of an extremely formal nature, being sharply divided up into different phases, viz.: (1) sitting at home with paper and pencil, miles and miles from any computer, I would think very, very hard about what I wanted the computer to do, and translate my intentions into a computer language--a series of alphanumeric symbols on a page. (2) I would carry this across a sort of informational cordon sanitaire (three miles of snowdrifts) to school and type those letters into a machine--not a computer--which would convert the symbols into binary numbers and record them visibly on a tape. (3) Then, through the rubber-cup modem, I would cause those numbers to be sent to the university mainframe, which would (4) do arithmetic on them and send different numbers back to the teletype. (5) The teletype would convert these numbers back into letters and hammer them out on a page and (6) I, watching, would construe the letters as meaningful symbols.

The division of responsibilities implied by all of this is admirably clean: computers do arithmetic on bits of information. Humans construe the bits as meaningful symbols. But this distinction is now being blurred, or at least complicated, by the advent of modern operating systems that use, and frequently abuse, the power of metaphor to make computers accessible to a larger audience. Along the way--possibly because of those metaphors, which make an operating system a sort of work of art--people start to get emotional, and grow attached to pieces of software in the way that my friend's dad did to his MGB.

People who have only interacted with computers through graphical user interfaces like the MacOS or Windows--which is to say, almost everyone who has ever used a computer--may have been startled, or at least bemused, to hear about the telegraph machine that I used to communicate with a computer in 1973. But there was, and is, a good reason for using this particular kind of technology. Human beings have various ways of communicating to each other, such as music, art, dance, and facial expressions, but some of these are more amenable than others to being expressed as strings of symbols. Written language is the easiest of all, because, of course, it consists of strings of symbols to begin with. If the symbols happen to belong to a phonetic alphabet (as opposed to, say, ideograms), converting them into bits is a trivial procedure, and one that was nailed, technologically, in the early nineteenth century, with the introduction of Morse code and other forms of telegraphy.

We had a human/computer interface a hundred years before we had computers. When computers came into being around the time of the Second World War, humans, quite naturally, communicated with them by simply grafting them on to the already-existing technologies for translating letters into bits and vice versa: teletypes and punch card machines.

These embodied two fundamentally different approaches to computing. When you were using cards, you'd punch a whole stack of them and run them through the reader all at once, which was called batch processing. You could also do batch processing with a teletype, as I have already described, by using the paper tape reader, and we were certainly encouraged to use this approach when I was in high school. But--though efforts were made to keep us unaware of this--the teletype could do something that the card reader could not. On the teletype, once the modem link was established, you could just type in a line and hit the return key. The teletype would send that line to the computer, which might or might not respond with some lines of its own, which the teletype would hammer out--producing, over time, a transcript of your exchange with the machine. This way of doing it did not even have a name at the time, but when, much later, an alternative became available, it was retroactively dubbed the Command Line Interface.

When I moved on to college, I did my computing in large, stifling rooms where scores of students would sit in front of slightly updated versions of the same machines and write computer programs: these used dot-matrix printing mechanisms, but were (from the computer's point of view) identical to the old teletypes. By that point, computers were better at time-sharing--that is, mainframes were still mainframes, but they were better at communicating with a large number of terminals at once. Consequently, it was no longer necessary to use batch processing. Card readers were shoved out into hallways and boiler rooms, and batch processing became a nerds-only kind of thing, and consequently took on a certain eldritch flavor among those of us who even knew it existed. We were all off the Batch, and on the Command Line, interface now--my very first shift in operating system paradigms, if only I'd known it.

A huge stack of accordion-fold paper sat on the floor underneath each one of these glorified teletypes, and miles of paper shuddered through their platens. Almost all of this paper was thrown away or recycled without ever having been touched by ink--an ecological atrocity so glaring that those machines soon replaced by video terminals--so-called "glass teletypes"--which were quieter and didn't waste paper. Again, though, from the computer's point of view these were indistinguishable from World War II-era teletype machines. In effect we still used Victorian technology to communicate with computers until about 1984, when the Macintosh was introduced with its Graphical User Interface. Even after that, the Command Line continued to exist as an underlying stratum--a sort of brainstem reflex--of many modern computer systems all through the heyday of Graphical User Interfaces, or GUIs as I will call them from now on.


Now the first job that any coder needs to do when writing a new piece of software is to figure out how to take the information that is being worked with (in a graphics program, an image; in a spreadsheet, a grid of numbers) and turn it into a linear string of bytes. These strings of bytes are commonly called files or (somewhat more hiply) streams. They are to telegrams what modern humans are to Cro-Magnon man, which is to say the same thing under a different name. All that you see on your computer screen--your Tomb Raider, your digitized voice mail messages, faxes, and word processing documents written in thirty-seven different typefaces--is still, from the computer's point of view, just like telegrams, except much longer, and demanding of more arithmetic.

The quickest way to get a taste of this is to fire up your web browser, visit a site, and then select the View/Document Source menu item. You will get a bunch of computer code that looks something like this: