Unix Quotes

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

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.

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.

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.

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

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.

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.

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.

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

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

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

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.

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.

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

During those same years, there were other achievements at Bell Labs that would, in time, alter the world. One occurred when several computer scientists at Murray Hill got together to write a revolutionary computer operating system they called Unix, which was written in a new computer language called C.

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.

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

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

Rule of Optimization: Prototype before polishing. Get it working before you optimize it.

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.

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

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

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

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

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.

with anything else under UNIX (of which Finux is a variant), there are a million options that only young, lonely, or obsessed people have the time and patience to explore.

As companies move toward distributed systems, Sybase and competing vendors—such as The ASK Group Inc., Informix Software Inc., and Oracle Corp.—are all offering products similar to System 10 . . . . Here we are in the “safe as milk” category, somewhat ironic in light of subsequent revelations about the limitations of Server 10. The innovations presented here are all continuous—performance, functionality, and capacity—and a number of other mainstream vendors are “all offering products similar” to it. Note the emphasis on company and market issues as opposed to product and technology. All of this speaks to mainstream positioning, either tornado or post-tornado. Since there is not a lot of emphasis on cutthroat competition, which one always expects with tornado products, the conclusion one would draw here is that Sybase 10 is on Main Street. Additional Indicators Beyond press coverage, a second source of clues to market status comes from the behavior of other companies in the infrastructure. Lew Platt at HP, for example, realized that their commercial Unix server business was in the tornado when software vendors were calling him rather than the other way around. Going further, when a tornado is under way, the easiest way to spot the gorilla is to look for the

And the next time you’re at a job interview where you need to demonstrate your skills by sharing your screen, establish your dominance early. Use ed.

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).

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.

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.

It's times like this when the age of the universe becomes a useful unit of measurement: 64-bit Unix time will last until twenty-one times the age of the universe from now - until (assuming we don't manage another upgrade in the meantime) December 4 in the year 292,277,026,596 CE, when all the computers will go down. On a Sunday.

from the many that are listed. In addition to selecting the version of sendmail you want, you must choose between two forms of compressed tar(1) distributions. Those that end in . Z are compressed withUnix compress(1); those that end in . gz are compressed withGNU gzip(1). The latter is the preferred form because the file is smaller and therefore quicker to transfer

Nobody, at least on the Unix side, had any idea they wanted it yet. Everyone uses them now but we had to spend a lot of time explaining to people why this was better than vi and GCC.

download the source you must select a file appropriate to your needs from the many that are listed. In addition to selecting the version of sendmail you want, you must choose between two forms of compressed tar(1) distributions. Those that end in . Z are compressed withUnix compress(1); those that end in . gz are compressed withGNU gzip(1). The latter is the preferred form because the file is smaller and therefore quicker to transfer. In addition to the two forms of distribution, each release has a PGP signature file associated withit.* Prior

strongest reasons early adopters of Linux chose it over, say, Windows NT was the powerful command line interface which made the “difficult tasks possible.” What This Book Is About This book is a broad overview of “living” on the Linux command line. Unlike some books that concentrate on just a single program, such as the shell program, bash, this book will try to convey how to get along with the command line interface in a larger sense. How does it all work? What can it do? What's the best way to use it? This is not a book about Linux system administration. While any serious discussion of the command line will invariably lead to system administration topics, this book only touches on a few administration issues. It will, however, prepare the reader for additional study by providing a solid foundation in the use of the command line, an essential tool for any serious system administration task. This book is very Linux-centric. Many other books try to broaden their appeal by including other platforms such as generic Unix and OS X. In doing so, they “water down” their content to feature only general topics. This book, on the other hand, only covers contemporary Linux distributions. Ninety-five percent of the content is useful for users of other Unix-like systems, but this book is highly

Unix, BSD, Linux, Mac OS, Windows are Monozukuri.

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.

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.

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.

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.

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!

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.

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.

There are two major products that come out of Berkeley: LSD and UNIX. We don’t believe this to be a coincidence.

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.

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

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

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.

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

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.

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

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

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.

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.

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.

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

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.

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

Web Application Development In this modern world of computer technology all people are using internet. In particular, to take advantage of this scenario the web provides a way for marketers to get to know the people visiting their sites and start communicating with them. One way of doing this is asking web visitors to subscribe to newsletters, to submit an application form when requesting information on products or provide details to customize their browsing experience when next visiting a particular website. In computing, a web application is a client–server software application in which the client runs in a web browser. HTML5 introduced explicit language support for making applications that are loaded as web pages, but can store data locally and continue to function while offline. Web Applications are dynamic web sites combined with server side programming which provide functionalities such as interacting with users, connecting to back-end databases, and generating results to browsers. Examples of Web Applications are Online Banking, Social Networking, Online Reservations, eCommerce / Shopping Cart Applications, Interactive Games, Online Training, Online Polls, Blogs, Online Forums, Content Management Systems, etc.. Applications are usually broken into logical chunks called “tiers”, where every tier is assigned a role. Traditional applications consist only of 1 tier, which resides on the client machine, but web applications lend themselves to an n-tiered approach by nature. Though many variations are possible, the most common structure is the three-tiered application. In its most common form, the three tiers are called presentation, application and storage, in this order. A web browser is the first tier (presentation), an engine using some dynamic Web content technology (such as ASP, CGI, ColdFusion, Dart, JSP/Java, Node.js, PHP, Python or Ruby on Rails) is the middle tier (application logic), and a database is the third tier (storage).The web browser sends requests to the middle tier, which services them by making queries and updates against the database and generates a user interface. Client Side Scripting / Coding – Client Side Scripting is the type of code that is executed or interpreted by browsers. Client Side Scripting is generally viewable by any visitor to a site (from the view menu click on “View Source” to view the source code). Below are some common Client Side Scripting technologies: HTML (HyperTextMarkup Language) CSS (Cascading Style Sheets) JavaScript Ajax (Asynchronous JavaScript and XML) jQuery (JavaScript Framework Library – commonly used in Ajax development) MooTools (JavaScript Framework Library – commonly used in Ajax development) Dojo Toolkit (JavaScript Framework Library – commonly used in Ajax development) Server Side Scripting / Coding – Server Side Scripting is the type of code that is executed or interpreted by the web server. Server Side Scripting is not viewable or accessible by any visitor or general public. Below are the common Server Side Scripting technologies: PHP (very common Server Side Scripting language – Linux / Unix based Open Source – free redistribution, usually combines with MySQL database) Zend Framework (PHP’s Object Oriented Web Application Framework) ASP (Microsoft Web Server (IIS) Scripting language) ASP.NET (Microsoft’s Web Application Framework – successor of ASP) ColdFusion (Adobe’s Web Application Framework) Ruby on Rails (Ruby programming’s Web Application Framework – free redistribution) Perl (general purpose high-level programming language and Server Side Scripting Language – free redistribution – lost its popularity to PHP) Python (general purpose high-level programming language and Server Side Scripting language – free redistribution). We also provide Training in various Computer Languages. TRIRID provide quality Web Application Development Services. Call us @ 8980010210

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.

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.

If a process tries to write to a shared page, it incurs a copy-on-write fault.[5

kswapd’s behavior is controlled by three parameters, called tries_base, tries_min, and swap_cluster,

system that is paging is writing selected, infrequently used pages of memory to disk,

while a system that is swapping is writing entire processes from memory to disk.

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.

Memory is consumed by four things: the kernel, filesystem caches, processes, and intimately shared memory.

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).

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.

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.

Buses implement either circuit-switched or packet-switched protocols.

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

Caches are organized into equal-sized chunks called lines.

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?

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.