Unix Quotes

UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity

Unix is not so much a product as it is a painstakingly compiled oral history of the hacker subculture. It is our Gilgamesh epic: a living body of narrative that many people know by heart, and tell over and over again—making their own personal embellishments whenever it strikes their fancy. The bad embellishments are shouted down, the good ones picked up by others, polished, improved, and, over time, incorporated into the story. […] 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.

An ugly system is one in which there are special interfaces for everything you want to do. Unix is the opposite. It gives you the building blocks that are sufficient for doing everything. That's what having a clean design is all about.

UTSL, which Maxine at first takes for an anagram of LUST or possibly SLUT but later learns is Unix for “Use The Source, Luke.

Forget UNIX - it will be gone in 5 years.

Second by second, the Queng Ho counted from the instant that a human had first set foot on Old Earth's moon. But if you looked at it still more closely ... the starting instant was actually about fifteen million seconds later, the 0-second of one of Humankind's first computer operating systems.

Over the years, Rao would master two computer languages, COBOL and BASIC, and would also go on to write code in the mainframe operating system UNIX. Narasimha

elders.’ ” Working in collaboration with a small group of programmers, Joy took on the task of rewriting UNIX, which was a software system

CSV (fields separated by commas, double quotes used to escape commas, no continuation lines) is rarely found under Unix.

There is a flip side to this. In the Unix world, libraries which are delivered as libraries should come with exerciser programs.

Levchin and Musk soon clashed on an issue that sounded technical but was also theological: whether to use Microsoft Windows or Unix as the main operating system.

The sched_setscheduler() system call changes both the scheduling policy and the priority of the process whose process ID is specified in pid. If pid is specified as 0, the attributes of the calling process are changed.

VI was predecessor to hundreds of word processing systems. By now, Unix folks see it as a bit stodgy—it hasn’t the versatility of Gnu-Emacs, nor the friendliness of more modern editors. Despite that, VI shows up on every Unix system.

When he finally settled down for the interview, he said that even the advent of the web would do little to stop Microsoft’s domination. “Windows has won,” he said. “It beat the Mac, unfortunately, it beat UNIX, it beat OS/2. An inferior product won.

That time in Seattle—during the lawsuit—was a fucking nightmare. I came out of it dead broke, without a house, without anything except a girlfriend and a knowledge of UNIX.” “Well, that’s something,” Avi says. “Normally those two are mutually exclusive.

The name UNIX began as a pun: because early versions of the operating system supported only one user—Ken Thompson—Peter Neumann, a security researcher at Stanford Research International, joked that it was an “emasculated Multics,” or “UNICS.” The spelling was eventually changed to UNIX.

So Apple needed a partner, one that could make a stable operating system, preferably one that was UNIX-like and had an object-oriented application layer. There was one company that could obviously supply such software—NeXT—but it would take a while for Apple to focus on it. Apple first homed in on

But Unix had a serious shortcoming: No common version existed. Over the years different versions of Unix had proliferated like weeds, so that an application written for one would not run unmodified on another. While DOS presented a single target to consumers, applications writers and computer makers, Unix did not.

NeXT and making Jobs its CEO. In the spoof Mike Markkula asked Jobs, “Do you want to spend the rest of your life selling UNIX with a sugarcoating, or change the world?” Jobs responded, “Because I’m now a father, I needed a steadier source of income.” The release noted that “because of his experience at Next, he is expected to bring

Apple’s chief technology officer, Ellen Hancock, argued for going with Sun’s UNIX-based Solaris operating system, even though it did not yet have a friendly user interface. Amelio began to favor using, of all things, Microsoft’s Windows NT, which he felt could be rejiggered on the surface to look and feel just like a Mac while being compatible

I’m glad someone’s finally giving ed the attention it deserves.

Transparency is therefore more than an esthetic triumph; it is a victory that will be reflected in lower costs throughout the software’s life cycle. 6.2.2

HP-UX is a pretty good implementation of BSD, although it's not as featureful as SunOS.

Python language is one example. As we noted above, it is also heavily used for mathematical and scientific papers, and will probably dominate that niche for some years yet. 18.3.3

As a system administrator, it's in your best interest to befriend data center technicians and bribe them with coffee, caffeinated soft drinks, and alcoholic beverages

A process is an instance of an executing program. In this section, we elaborate on this definition and clarify the distinction between a program and a process.

graphical user interfaces make easy tasks easy, while command line interfaces make difficult tasks possible

Chapter 5-"Now THAT'S Leverage" discusses the idea of "software leverage," where reusing components results in greater impact. We see how the use of shell scripts achieves a high degree of leverage.

It might seem that security should gradually improve over time as security problems are discovered and corrected, but unfortunately this does not seem to be the case. System software is growing ever more complicated, hackers are becoming better and better organized, and computers are connecting more and more intimately on the Internet. Security is an ongoing battle that can never really be won.

To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive. Oren

The label “jack-of-all-trades but master of none” is normally meant to be derogatory, implying that the labelee lacks the focus to really dive into a subject and master it. But, when your online shopping application is on the fritz and you’re losing orders by the hundreds as each hour passes, it’s the jack-of-all-trades who not only knows how the application’s code works but can also do low-level UNIX debugging of your web server processes, analyze your RDBMS’s configuration for potential performance bottlenecks, and check your network’s router configuration for hard-to-find problems. And, more important, after finding the problem, the jack-of-all-trades can quickly make architecture and design decisions, implement code fixes, and deploy a new fixed system to production. In this scenario, the manufacturing scenario seems quaint at best and critically flawed at worst.

NIH syndrome is characterized by a decision to discard all of what the other developer accomplished with the intent of demonstrating a superior solution. Such an act of sheer egotism demonstrates little interest in preserving the best of another's work and using it as a springboard to newer heights.

Use # as an introducer for comments. It is good to have a way to embed annotations and comments in data files. It’s best if they’re actually part of the file structure, and so will be preserved by tools that know its format. For comments that are not preserved during parsing, # is the conventional start character.

Top-down tends to be good practice when three preconditions are true: (a) you can specify in advance precisely what the program is to do, (b) the specification is unlikely to change significantly during implementation, and (c) you have a lot of freedom in choosing, at a low level, how the program is to get that job done.

There was, of course, one other option. Two years earlier Macworld magazine columnist (and former Apple software evangelist) Guy Kawasaki had published a parody press release joking that Apple was buying NeXT and making Jobs its CEO. In the spoof Mike Markkula asked Jobs, “Do you want to spend the rest of your life selling UNIX with a sugarcoating, or change the world?” Jobs responded, “Because I’m now a father, I needed a steadier source of income.” The release noted that “because of his experience at Next, he is expected to bring a newfound sense of humility back to Apple.” It also quoted Bill Gates as saying there would now be more innovations from Jobs that Microsoft could copy. Everything in the press release was meant as a joke, of course. But reality has an odd habit of catching up with satire.

When a process is rescheduled to run on a multiprocessor system, it doesn’t necessarily run on the same CPU on which it last executed. The usual reason it may run on another CPU is that the original CPU is already busy. When a process changes CPUs, there is a performance impact: in order for a line of the process’s data to be loaded into the cache of the new CPU, it must first be invalidated (i.e., either discarded if it is unmodified, or flushed to main memory if it was modified), if present in the cache of the old CPU. (To prevent cache inconsistencies, multiprocessor architectures allow data to be kept in only one CPU cache at a time.) This invalidation costs execution time. Because of this performance impact, the Linux (2.6) kernel tries to ensure soft CPU affinity for a process — wherever possible, the process is rescheduled to run on the same CPU.

#1. No Escape and feature keys Today’s Apple Event confirmed many of the rumors surrounding the lengthy-awaited refresh of the Macbook Pro line. The Escape and Function keys at the laptops had been deserted in choose of a hint bar that changed relying at the software that is getting used. The last the Macbook Pro got a chief update was a shocking 4 years in the past and many guides are celebrating the brand new design. However, the lack of bodily Escape and Function keys is a disaster for one major set of Apple’s customers — Developers. Let’s test numbers: There are ~ 19 million developers inside the global. And Apple has managed to promote ~19 million Macs over the past four quarters. What a twist of fate! Yes, builders are drawn toward Apple products mainly for software program reasons: the Unix-like running gadget and the proprietary development atmosphere. But builders want to have a useful keyboard to make use of that software and now they don’t. Why Tim Cook, why? This isn’t to say that the contact bar is an inherently awful concept. You should locate it on pinnacle of the Esc and feature keys as opposed to doing away with them completely! Something like this: #2 Power. Almost no improvement for RAM and a processor The 2016 MacBook Pro ships with RAM and processor specifications that are nearly equal to the 2010 model. Deja vu? RAM: At least it appears like that, because the MacBook Pro has had alternatives of as much as 16 GB of RAM in view that 2010. The best difference now's that you pay for the update. Processors: The MacBook Pro had options with 2.4 gigahertz twin-middle processors again in 2010. Anything new in 2016? Not absolutely, well… nope.

We need to be humble enough to recognize that unforeseen things can and do happen that are nobody’s fault. A good example of this occurred during the making of Toy Story 2. Earlier, when I described the evolution of that movie, I explained that our decision to overhaul the film so late in the game led to a meltdown of our workforce. This meltdown was the big unexpected event, and our response to it became part of our mythology. But about ten months before the reboot was ordered, in the winter of 1998, we’d been hit with a series of three smaller, random events—the first of which would threaten the future of Pixar. To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive. Oren Jacobs, one of the lead technical directors on the movie, remembers watching this occur in real time. At first, he couldn’t believe what he was seeing. Then, he was frantically dialing the phone to reach systems. “Pull out the plug on the Toy Story 2 master machine!” he screamed. When the guy on the other end asked, sensibly, why, Oren screamed louder: “Please, God, just pull it out as fast as you can!” The systems guy moved quickly, but still, two years of work—90 percent of the film—had been erased in a matter of seconds. An hour later, Oren and his boss, Galyn Susman, were in my office, trying to figure out what we would do next. “Don’t worry,” we all reassured each other. “We’ll restore the data from the backup system tonight. We’ll only lose half a day of work.” But then came random event number two: The backup system, we discovered, hadn’t been working correctly. The mechanism we had in place specifically to help us recover from data failures had itself failed. Toy Story 2 was gone and, at this point, the urge to panic was quite real. To reassemble the film would have taken thirty people a solid year. I remember the meeting when, as this devastating reality began to sink in, the company’s leaders gathered in a conference room to discuss our options—of which there seemed to be none. Then, about an hour into our discussion, Galyn Susman, the movie’s supervising technical director, remembered something: “Wait,” she said. “I might have a backup on my home computer.” About six months before, Galyn had had her second baby, which required that she spend more of her time working from home. To make that process more convenient, she’d set up a system that copied the entire film database to her home computer, automatically, once a week. This—our third random event—would be our salvation. Within a minute of her epiphany, Galyn and Oren were in her Volvo, speeding to her home in San Anselmo. They got her computer, wrapped it in blankets, and placed it carefully in the backseat. Then they drove in the slow lane all the way back to the office, where the machine was, as Oren describes it, “carried into Pixar like an Egyptian pharaoh.” Thanks to Galyn’s files, Woody was back—along with the rest of the movie.

UNIX. Understanding the meagerly documented, demanding, and complex sources of

Mensagem postada na Usenet, 21 de agosto de 1994:   Start-up com bom capital busca programadores de C/C++/Unix muito talentosos para projeto pioneiro de comércio pela internet. É necessário ter experiência em projetar e desenvolver sistemas grandes e complexos (que possam ser atualizados) e ser capaz de fazer isso em um terço do tempo considerado possível. Exigimos bacharelado, mestrado ou Ph.D. em ciência da computação ou formação equivalente. Grande facilidade de comunicação é essencial. É desejável, mas não imprescindível, ter familiaridade com servidores de Web e HTML. Esperamos trabalhar com pessoas talentosas, motivadas, apaixonadas e interessantes que tenham disponibilidade para se mudar para Seattle (ajudaremos com os custos da mudança). Oferecemos uma participação significativa nas ações da empresa. Enviar currículo e carta de apresentação para Jeff Bezos. Endereço: Cadabra Inc. 10.704 N.E. 28th St., Bellevue, WA 98004 Oferecemos as mesmas oportunidades para todos.

Technologist Kevin Kelly suggests, “If a thousand lines of letters in UNIX qualifies as a technology, . . . then a thousand lines of letters in English (Hamlet) must qualify as well. They both can change our behavior, alter the course of events, or enable future inventions. A Shakespeare sonnet and a Bach fugue, then, are in the same category as Google’s search engine and the iPod. They are something useful produced by a mind.

To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive.

In 1958 AT&T, the owner of Bell Labs, was served with an antitrust court order that forbade it to ever enter the computer business and that forced it to license any non-telephone inventions to the whole world. This odd ruling turned Unix into a worldwide phenomenon, as it spread from one corner of the computer world to the other.

Modern Operating Systems Andrew S. Taunenbaum The Design of the UNIX Operating System Andrew S. Taunenbaum Object-Oriented Analysis and Design with Applications Booch Design Patterns: Elements of Reusable Object-Oriented Software Gamma

I took 17 computer science classes and made an A in 11 of them. 1 point away from an A in 3 of them and the rest of them didn't matter. Math is a tool for physics,chemistry,biology/basic computation and nothing else. CS I(Pascal Vax), CS II(Pascal Vax), Sr. Software Engineering, Sr. Distributed Systems, Sr. Research, Sr. Operating Systems, Sr. Unix Operating Systems, Data Structures, Sr. Object Oriented A&D, CS (perl/linux), Sr. Java Programming, Information Systems Design, Jr. Unix Operating Systems, Microprocessors, Programming Algorithms, Calculus I,II,III, B Differential Equations, TI-89 Mathematical Reasoning, 92 C++ Programming, Assembly 8086, Digital Computer Organization, Discrete Math I,II, B Statistics for the Engineering & Sciences (w/permutations & combinatorics) -- A-American Literature A-United States History 1865 CLEP-full year english CLEP-full year biology A-Psychology A-Environmental Ethics

They learned that small programs, like small cars, handled better, were more adaptable, and were easier to maintain than large programs.

System administrators often help organizations develop sensible policies that meet the letter and intent of the law and yet still promote progress and productivity.

The bank knew exactly what it was looking for and how to go about it. There was consensus on two critical aspects: the system had to be centralized and had to be based on UNIX, even if that meant spending tonnes of money. MicroBanker, a fully integrated online banking automation system, developed by Citicorp Information Technology Industries Ltd (Citil), a Citibank subsidiary, fit the bill, but Citil was not willing to deal with HDFC Bank. A small outfit, Citil thought, would not be able to afford the system. Citil was expanding operations in Africa and Europe and was not too keen to sell the software to a start-up Indian bank. While Citil reluctantly made a presentation on the system, Citibank intervened before a deal could be signed, saying that selling MicroBanker to HDFC Bank could give the Indian bank more muscle as a competitor. Aditya had to call Rajesh Hukku, Citil head, to play ball and he relented. Citil later became i-Flex Solutions Ltd (now Oracle Financial Services Software Ltd).

Usenet bulletin-board posting, August 21, 1994: Well-capitalized start-up seeks extremely talented C/C++/Unix developers to help pioneer commerce on the Internet. You must have experience designing and building large and complex (yet maintainable) systems, and you should be able to do so in about one-third the time that most competent people think possible. You should have a BS, MS, or PhD in Computer Science or the equivalent. Top-notch communication skills are essential. Familiarity with web servers and HTML would be helpful but is not necessary. Expect talented, motivated, intense, and interesting co-workers. Must be willing to relocate to the Seattle area (we will help cover moving costs). Your compensation will include meaningful equity ownership. Send resume and cover letter to Jeff Bezos.

When the superior programmer refrains from coding, his force is felt for a thousand miles.

RCS was the first version control tool I used. When I was at Spyglass, we had a team of 50 or so developers across three platforms using RCS on a shared code base. Since RCS never had support for networking, people on Windows and Mac had to log in to the Sun workstation that hosted RCS, FTP their code changes up there, and then check them in from the Unix shell. It was an interesting experience just trying to get all that to work.

NCA uses a kernel module to transparently cache static web content in a kernel memory buffer, and replies to HTTP document requests for documents in its cache without ever waking up the application web server.

John Hennessy and David Patterson: they are titled Computer Organization and Design: The Hardware/Software Interface and Computer Architecture: A Quantitative Approach (both published by Morgan Kaufmann).

The first represents the amount of time required to read or write a given location in memory, and is called the memory access time.

second, the memory cycle time, describes how frequently you can repeat a memory reference.

Paging is not necessarily indicative of a problem; it is the action of the page scanner to try and increase the size of the free list by moving inactive pages to disk.

One of the many consequences of the exponential power-versus-time curve in computing, and the corresponding pace of software development, is that 50% of what one knows becomes obsolete over every 18 months.

By mid-1970, they had a preliminary version up and running. Somewhere along the way, moreover, their homebrew operating system had acquired a name. According to one version of the story, the name signified “one of whatever Multics was many of.” According to another, it stood for “Multics without balls.” But either way it came out the same: Unix.

collect all the code that had to be customized for each new computer or disk drive and put it into a small Unix-like kernel that he called the Basic Input/Output System, or BIOS.

Un shell permite ser ejecutado de forma interactiva cuando acepta comandos directamente desde el teclado, no interactivos cuando aceptas comandos que provienen de un archivo.

- ¿Que opción del comando ls puede ser usado para listar archivos y directorios de forma recursiva?

Randy and Amy had spent a full hour talking to Scott and Laura last night; they were the only people who made any effort to make Amy feel welcome. Randy hadn’t the faintest idea what these people thought of him and what he had done, but he could sense right away that, essentially that was not the issue because even if they thought he had done something evil, they at least had a framework, a sort of procedure manual, for dealing with transgressions. To translate it into UNIX system administration terms (Randy’s fundamental metaphor for just about everything), the post- modern, politically correct atheists were like people who had suddenly found themselves in charge of a big and unfathomably complex computer system (viz. society) with no documentation or instructions of any kind, and so whose only way to keep the thing running was to invent and enforce certain rules with a kind of neo-Puritanical rigor, because they were at a loss to deal with any deviations from what they saw as the norm. Whereas people who were wired into a church were like UNIX system administrators who, while they might not understand everything, at least had some documentation, some FAQs and How-tos and README files, providing some guidance on what to do when things got out of whack. They were, in other words, capable of displaying adaptability.

Convert Text Files from Windows Format to Linux Format and Vice-Versa $ dos2unix $ unix2dos Sooner or later you're going to be sent a file or download one that uses a pair of CR (carriage return) and LF (line feed) characters to terminate lines in the file.  Those type of files are Windows/DOS formatted.  Unix-like operating systems simply use the LF character to terminate a line.  Sometimes this can cause issues.  To convert the file to a unix-like format, use dos2unix.  To examine the line termination characters use "cat -A" or the "file" command. $

To design for compactness and orthogonality, start from zero. Zen teaches that attachment leads to suffering; experience with software design teaches that attachment to unnoticed assumptions leads to non-orthogonality, noncompact designs, and projects that fail or become maintenance nightmares.

To design the perfect anti-Unix, write an operating system that thinks it knows what you’re doing better than you do. And then adds injury to insult by getting it wrong.

Make each program do one thing well. To do a new job, build afresh rather than complicate old programs by adding new features.

first of which would threaten the future of Pixar. To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive.

there are some problems no Unix command can address.

There are many different Unix shells, but all derive several of their features from the Bourne shell (/bin/sh), a standard shell developed at Bell Labs for early versions of Unix. Every Unix system needs the Bourne shell in order to function correctly, as you will see throughout this book. Linux uses an enhanced version of the Bourne shell called bash or the “Bourne-again” shell. The bash shell is the default shell on most Linux distributions, and /bin/sh is normally a link to bash on a Linux system.

When you feel the urge to design a complex binary file format, or a complex binary application protocol, it is generally wise to lie down until the feeling passes.

Tools that look glossy but shatter under stress are not good long-term value. Unix

it is not really in most vendors’ interest for the standards definition process to ever stop.

When you see the right thing, do it—this may look like more work in the short term, but it’s the path of least effort in the long run. If you don’t know what the right thing is, do the minimum necessary to get the job done, at least until you figure out what the right thing is. To do the Unix philosophy right, you have to be loyal to excellence. You have to believe that software design is a craft worth all the intelligence, creativity, and passion you can muster. Otherwise you won’t look past the easy, stereotyped ways of approaching design and implementation; you’ll rush into coding when you should be thinking. You’ll carelessly complicate when you should be relentlessly simplifying—and then you’ll wonder why your code bloats and debugging is so hard.

If you have any trouble sounding condescending, find a Unix user to show you how it’s done. Dilbert newsletter 3.0, 1994 —Scott Adams

Rushing to optimize before the bottlenecks are known may be the only error to have ruined more designs than feature creep. From tortured code to incomprehensible data layouts, the results of obsessing about speed or memory or disk usage at the expense of transparency and simplicity are everywhere. They spawn innumerable bugs and cost millions of man-hours—often, just to get marginal gains in the use of some resource much less expensive than debugging time. Disturbingly often, premature local optimization actually hinders global optimization (and hence reduces overall performance). A prematurely optimized portion of a design frequently interferes with changes that would have much higher payoffs across the whole design, so you end up with both inferior performance and excessively complex code.

As with buildings, it’s easier to repair superstructure on top of a solid foundation than it is to replace the foundations without trashing the superstructure.

Mixing languages is better than writing everything in one, if and only if using only that one is likely to overcomplicate the program.

Are the individual functions in your modules too large? This is not so much a matter of line count as it is of internal complexity. If you can’t informally describe a function’s contract with its callers in one line, the function is probably too large.9 9 Many years ago, I learned from Kernighan & Plauger’s The Elements of Programming Style a useful rule. Write that one-line comment immediately after the prototype of your function. For every function, without exception.

One of the main lessons of Zen is that we ordinarily see the world through a haze of preconceptions and fixed ideas that proceed from our desires. To achieve enlightenment, we must follow the Zen teaching not merely to let go of desire and attachment, but to experience reality exactly as it is—without the preconceptions and the fixed ideas getting in the way. This

On a UNIX system, everything is a file; if something is not a file, it is a process.

Web pages get bogged down in the dispute over whether the reader or author should control the appearance.

Poor performance was a common failing of most new programs. The annals of software amply showed this; nearly every landmark system, from IBM’s 360 to the various flavors of Unix to Microsoft’s Windows, was released in an immature state and evolved over time to win broader acceptance. Indeed, people expected the first commercial release of a new program to contain flaws of all sorts.

The nightmare scenario is one in which corporate monopolism and statist power-seeking, always natural allies, feed back into each other and create rationales for increasing regulation, repression, and criminalization of digital speech.

As a case in point, the ps used by Linux is a trisexual and hermaphroditic version that understands multiple option sets and uses an environment variable to tell it what universe it’s living in.

Fire Fighting Although helping users with their various problems is rarely included in a system administrator’s job description, it claims a significant portion of most administrators’ workdays. System administrators are bombarded with problems ranging from “It worked yesterday and now it doesn’t! What did you change?” to “I spilled coffee on my keyboard! Should I pour water on it to wash it out?” In most cases, your response to these issues affects your perceived value as an administrator far more than does any actual technical skill you might possess. You can either howl at the injustice of it all, or you can delight in the fact that a single well-handled trouble ticket scores as many brownie points as five hours of midnight debugging. You pick!

found on other Unix-like systems. The design is actually specified in a published standard called the Linux Filesystem Hierarchy Standard.

Vernor Vinge's novel, A Deepness in the Sky, describes a spacefaring trading civilization tens of thousands of years (hundreds of gigaseconds) in the future that apparently still uses the Unix epoch. The "programmer-archaeologist" responsible for finding and maintaining usable code in mature computer systems first believes that the epoch refers to the time when man first walked on the Moon, but then realizes that it is "the 0-second of one of Humankind’s first computer operating systems.

HP, Oracle(구 SUN)사의 서버는 전용 OS를 별도로 사야만 합니다. 아니 오히려 서버에 잘 맞는 Unix 를 쓰기 위해서 HP, Oracle사의 서버를 사기도 했습니다. 그런데 요즘에는 무료 운영체제인 Linux가 Unix를 충분히 대체할 수 있게 되었습니다. 그래서 대부분 서버에 Linux 를 설치해서 사용합니다.

Это сообщение представлено вам при поддержке Linux, свободного Unix. Windows без X — это как заниматься сексом в одиночку. [пп: пропаганда наркотиков вырезана в соответствии с законодательством РФ, на всякий случай] Яблоки были проблемой еще в Эдеме. Linux — способ избавиться от вирусов в автозагрузке. — mwikholm@at8.abo.fi, MaDsen Wikholm

Use manual sanity checks in data pipelines. When optimizing data processing systems, it’s easy to stay in the “binary mindset” mode, using tight pipelines, efficient binary data formats, and compressed I/O. As the data passes through the system unseen, unchecked (except for perhaps its type), it remains invisible until something outright blows up. Then debugging commences. I advocate sprinkling a few simple log messages throughout the code, showing what the data looks like at various internal points of processing, as good practice — nothing fancy, just an analogy to the Unix head command, picking and visualizing a few data points. Not only does this help during the aforementioned debugging, but seeing the data in a human-readable format leads to “aha!” moments surprisingly often, even when all seems to be going well. Strange tokenization! They promised input would always be encoded in latin1! How did a document in this language get in there? Image files leaked into a pipeline that expects and parses text files! These are often insights that go way beyond those offered by automatic type checking or a fixed unit test, hinting at issues beyond component boundaries. Real-world data is messy. Catch early even things that wouldn’t necessarily lead to exceptions or glaring errors. Err on the side of too much verbosity.

The history of Unix should have prepared us for what we’re learning from Linux (and what I’ve verified experimentally on a smaller scale by deliberately copying Linus’s methodsNote 12). That is, while coding remains an essentially solitary activity, the really great hacks come from harnessing the attention and brainpower of entire communities. The developer who uses only his or her own brain in a closed project is going to fall behind the developer who knows how to create an open, evolutionary context in which feedback exploring the design space, code contributions, bug-spotting, and other improvements come from from hundreds (perhaps thousands) of people.

Terminal Guides is a comprehensive online resource designed for both new and experienced users of Unix-like operating systems. It offers a range of tutorials, tips, and guides on using the terminal, managing files, and performing system tasks efficiently.

I once worked on a project in which a software product originally written for UNIX was being redesigned and implemented on Windows NT. Most of the programming team consisted of programmers who had great facility with Windows and Microsoft Visual C++. In no time at all, it seemed, they had generated many screens full of windows and toolbars and dialogues, all with connections to networks and data sources, thousands and thousands of lines of code. But when the inevitable difficulties of debugging came, they seemed at sea. In the face of the usual weird and and unexplainable outcomes, they stood agog. It was left to the UNIX-trained programmers to fix things. The UNIX team members were accustomed to not knowing. Their view of programming as language-as-text gave them the patience to look slowly through the code. In the end, the overall 'productivity' of the system, the fact that it came into being at all, was not the handiwork of tools that sought to make programming seem easy, but the work of engineers who had no fear of 'hard.

Unix has always lurked provocatively in the background of the operating system wars, like the Russian Army. Most people know it only by reputation, and its reputation, as the Dilbert cartoon suggests, is mixed. But everyone seems to agree that if it could only get its act together and stop surrendering vast tracts of rich agricultural land and hundreds of thousands of prisoners of war to the onrushing invaders, it could stomp them (and all other opposition) flat.

Thompson, who designed and implemented the first UNIX system, has stated that he much prefers printf debugging.24 But as Baird put it, “If you are a genius like Ken Thompson, you are going to write good code.”25 The rest of us need to move beyond printf debugging to get our code working, as I rapidly discovered once I started working on the internals of Windows NT at Microsoft (the fundamental skill is learning to use a specialized piece of software called a debugger, which can examine the memory of another program).

processor performance doubles roughly every eighteen months, but memory performance doubles roughly every seven years.

Caches are organized into equal-sized chunks called lines.

Linux addresses this issue by adopting an empirical rule related to the processor’s cache size: the larger the processor’s cache, the longer a process will wait for a piece of time on that processor.

Every LWP has a kernel thread, but every kernel thread need not have an LWP:

Threads generally fall into five categories for scheduling: timesharing (ts), interactive (ia), kernel, real-time (rt), and interrupt.