“The Unix Philosophy”
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It's Complicated but It's Probably Already Booting Your Computer
FAQ SYSTEMD SYSTEMD It’s complicated but it’s probably already booting your computer. dynamically connect to your network, a runlevel of 1 for a single-user mode, GRAHAM MORRISON while syslogd pools all the system runlevel 3 for the same command messages together to create a log of prompt we described earlier, and Surely the ‘d’ in Systemd is everything important. Another daemon, runlevel 5 to launch a graphical a typo? though it lacks the ‘d’, is init – famous environment. Changing this for your No –it’s a form of Unix notation for being the first process that runs on next boot often involved editing the used to signify a daemon. your system. /etc/inittab file, and you’d soon get used to manually starting and stopping You mean like those little Isn’t init used to switch your own services simply by executing devils inhabiting Dante’s between the command-line the scripts you found. underworld? and the graphical desktop? There is a link in that Unix usage For many of us, yes. This was the You seem to be using the past of the term daemon supposedly main way of going from the tense for all this talk about the comes from Greek mythology, where desktop to a command line and back init daemon… daemons invisibly wove their magic again without trying to figure out which That’s because the and benign influence. The word is today processes to kill or start manually. aforementioned Systemd wants more commonly spelt ‘demon’, which Typing init 3 would typically close any to put init in the past. -
Getting to Grips with Unix and the Linux Family
Getting to grips with Unix and the Linux family David Chiappini, Giulio Pasqualetti, Tommaso Redaelli Torino, International Conference of Physics Students August 10, 2017 According to the booklet At this end of this session, you can expect: • To have an overview of the history of computer science • To understand the general functioning and similarities of Unix-like systems • To be able to distinguish the features of different Linux distributions • To be able to use basic Linux commands • To know how to build your own operating system • To hack the NSA • To produce the worst software bug EVER According to the booklet update At this end of this session, you can expect: • To have an overview of the history of computer science • To understand the general functioning and similarities of Unix-like systems • To be able to distinguish the features of different Linux distributions • To be able to use basic Linux commands • To know how to build your own operating system • To hack the NSA • To produce the worst software bug EVER A first data analysis with the shell, sed & awk an interactive workshop 1 at the beginning, there was UNIX... 2 ...then there was GNU 3 getting hands dirty common commands wait till you see piping 4 regular expressions 5 sed 6 awk 7 challenge time What's UNIX • Bell Labs was a really cool place to be in the 60s-70s • UNIX was a OS developed by Bell labs • they used C, which was also developed there • UNIX became the de facto standard on how to make an OS UNIX Philosophy • Write programs that do one thing and do it well. -
Introduction to Computer System
Chapter 1 INTRODUCTION TO COMPUTER SYSTEM 1.0 Objectives 1.1 Introduction –Computer? 1.2 Evolution of Computers 1.3 Classification of Computers 1.4 Applications of Computers 1.5 Advantages and Disadvantages of Computers 1.6 Similarities Difference between computer and Human 1.7 A Computer System 1.8 Components of a Computer System 1.9 Summary 1.10 Check your Progress - Answers 1.11 Questions for Self – Study 1.12 Suggested Readings 1.0 OBJECTIVES After studying this chapter you will be able to: Learn the concept of a system in general and the computer system in specific. Learn and understand how the computers have evolved dramatically within a very short span, from very huge machines of the past, to very compact designs of the present with tremendous advances in technology. Understand the general classifications of computers. Study computer applications. Understand the typical characteristics of computers which are speed, accuracy, efficiency, storage capacity, versatility. Understand limitations of the computer. Discuss the similarities and differences between the human and the computer. Understand the Component of the computer. 1.1 INTRODUCTION- Computer Today, almost all of us in the world make use of computers in one way or the other. It finds applications in various fields of engineering, medicine, commercial, research and others. Not only in these sophisticated areas, but also in our daily lives, computers have become indispensable. They are present everywhere, in all the dev ices that we use daily like cars, games, washing machines, microwaves etc. and in day to day computations like banking, reservations, electronic mails, internet and many more. -
The Strange Birth and Long Life of Unix - IEEE Spectrum Page 1 of 6
The Strange Birth and Long Life of Unix - IEEE Spectrum Page 1 of 6 COMPUTING / SOFTWARE FEATURE The Strange Birth and Long Life of Unix The classic operating system turns 40, and its progeny abound By WARREN TOOMEY / DECEMBER 2011 They say that when one door closes on you, another opens. People generally offer this bit of wisdom just to lend some solace after a misfortune. But sometimes it's actually true. It certainly was for Ken Thompson and the late Dennis Ritchie, two of the greats of 20th-century information technology, when they created the Unix operating system, now considered one of the most inspiring and influential pieces of software ever written. A door had slammed shut for Thompson and Ritchie in March of 1969, when their employer, the American Telephone & Telegraph Co., withdrew from a collaborative project with the Photo: Alcatel-Lucent Massachusetts Institute of KEY FIGURES: Ken Thompson [seated] types as Dennis Ritchie looks on in 1972, shortly Technology and General Electric after they and their Bell Labs colleagues invented Unix. to create an interactive time- sharing system called Multics, which stood for "Multiplexed Information and Computing Service." Time-sharing, a technique that lets multiple people use a single computer simultaneously, had been invented only a decade earlier. Multics was to combine time-sharing with other technological advances of the era, allowing users to phone a computer from remote terminals and then read e -mail, edit documents, run calculations, and so forth. It was to be a great leap forward from the way computers were mostly being used, with people tediously preparing and submitting batch jobs on punch cards to be run one by one. -
The Strange Birth and Long Life of Unix - IEEE Spectrum
The Strange Birth and Long Life of Unix - IEEE Spectrum http://spectrum.ieee.org/computing/software/the-strange-birth-and-long-li... COMPUTING / SOFTWARE FEATURE The Strange Birth and Long Life of Unix The classic operating system turns 40, and its progeny abound By WARREN TOOMEY / DECEMBER 2011 They say that when one door closes on you, another opens. People generally offer this bit of wisdom just to lend some solace after a misfortune. But sometimes it's actually true. It certainly was for Ken Thompson and the late Dennis Ritchie, two of the greats of 20th-century information technology, when they created the Unix operating system, now considered one of the most inspiring and influential pieces of software ever written. A door had slammed shut for Thompson and Ritchie in March of 1969, when their employer, the American Telephone & Telegraph Co., withdrew from a collaborative project with the Photo: Alcatel-Lucent Massachusetts Institute of KEY FIGURES: Ken Thompson [seated] types as Dennis Ritchie looks on in 1972, shortly Technology and General Electric after they and their Bell Labs colleagues invented Unix. to create an interactive time-sharing system called Multics, which stood for "Multiplexed Information and Computing Service." Time-sharing, a technique that lets multiple people use a single computer simultaneously, had been invented only a decade earlier. Multics was to combine time-sharing with other technological advances of the era, allowing users to phone a computer from remote terminals and then read e-mail, edit documents, run calculations, and so forth. It was to be a great leap forward from the way computers were mostly being used, with people tediously preparing and submitting batch jobs on punch cards to be run one by one. -
SIGOPS Annual Report 2012
SIGOPS Annual Report 2012 Fiscal Year July 2012-June 2013 Submitted by Jeanna Matthews, SIGOPS Chair Overview SIGOPS is a vibrant community of people with interests in “operatinG systems” in the broadest sense, includinG topics such as distributed computing, storaGe systems, security, concurrency, middleware, mobility, virtualization, networkinG, cloud computinG, datacenter software, and Internet services. We sponsor a number of top conferences, provide travel Grants to students, present yearly awards, disseminate information to members electronically, and collaborate with other SIGs on important programs for computing professionals. Officers It was the second year for officers: Jeanna Matthews (Clarkson University) as Chair, GeorGe Candea (EPFL) as Vice Chair, Dilma da Silva (Qualcomm) as Treasurer and Muli Ben-Yehuda (Technion) as Information Director. As has been typical, elected officers agreed to continue for a second and final two- year term beginning July 2013. Shan Lu (University of Wisconsin) will replace Muli Ben-Yehuda as Information Director as of AuGust 2013. Awards We have an excitinG new award to announce – the SIGOPS Dennis M. Ritchie Doctoral Dissertation Award. SIGOPS has lonG been lackinG a doctoral dissertation award, such as those offered by SIGCOMM, Eurosys, SIGPLAN, and SIGMOD. This new award fills this Gap and also honors the contributions to computer science that Dennis Ritchie made durinG his life. With this award, ACM SIGOPS will encouraGe the creativity that Ritchie embodied and provide a reminder of Ritchie's leGacy and what a difference a person can make in the field of software systems research. The award is funded by AT&T Research and Alcatel-Lucent Bell Labs, companies that both have a strong connection to AT&T Bell Laboratories where Dennis Ritchie did his seminal work. -
July 1St Century and a Half Later by 1960S
The underlying technology, the After CTSS, he moved onto Leibniz wheel, was reused a Multics [Nov 30] during the mid- July 1st century and a half later by 1960s. That OS is often deemed Thomas de Colmar [May 5] in his a commercial failure, but arithmometer, the first mass- nevertheless had an enormous Gottfried Wilhelm produced mechanical calculator. influence on the design of later systems. For example, UNIX was In 1961, Norbert Wiener [Nov written by two ex-Multics (von) Leibni[t]z 26] suggested that Leibniz programmers, Ken Thompson should be considered the patron Born: July 1, 1646; [Feb 4] and Dennis Ritchie [Sept saint of cybernetics. Leipzig, Saxony 9]. Died: Nov. 14, 1716 Corbató is credited with the first During the 1670s, Leibniz use of passwords (to secure independently developed a very Hans Peter Luhn access to CTSS), although he similar theory of calculus to that Born: July 1, 1896; himself suggested that they first of Issac Newton. More appeared in IBM’s SABRE Barmen, Germany importantly for us, at around the ticketing system [Nov 5]. same time, in 1672, Leibniz cam Died: August 19, 1964 Corbató’s Law: The number of up with the first practical Luhn is sometimes called “the lines of code a programmer can calculating machine, which he father of information retrieval”, write in a fixed period of time is called the “Step Reckoner”. He due to his invention of the Luhn the same independent of the had the initial idea from algorithm, KWIC (Key Words In language used. examining a pedometer. Context) indexing, and Selective It was the first calculator that Dissemination of Information could perform all four arithmetic (“SDI”) operations, although the carry The Luhn algorithm is a Project MAC operation wasn't fully checksum formula used to July 1, 1963 mechanized. -
If Data Is Confidential and Available but Altered Decryption of Altered Data Usually Gives Garbage Exception: Electronic-Codeboo
38 40 If Data is Confidential and Available but Altered Encryption • do not use ECB–Mode • use CBC– or CTR–mode (recommendation Schneier/Ferguson) • use AES or one of the finalists – Twofish (Schneier, Ferguson, Kelsey, Whiting, Wagner, Hall) decryption of altered data usually gives garbage – Serpent (Anderson, Biham, Knudsen) – MARS (Coppersmith et al., IBM) exception: electronic-codebook-mode (ECB) (uses independent blocks) – RC6 (Rivest, patented by RSA) 39 41 ECB-Mode Encrypted Penguin If Data is Non-Alterable and Confidential but not Available ,,Your message with authenticator 08931281763e1de003e5f930c449bf791c9f0db6 encryption is block by block has been received, but unfortunately the server is down. ❀ every block gets another color Your mail-service will never be accessible.” Example: lavabit.com, Snowden’s e-Mail-Provider 42 44 Authorization: Who is Allowed to Do All This? Problem: Person/Process/Role ⇐⇒ String (2) How to link a person to a string? • Person knows something (password, secret cryptographic key). • Person has something (token, USB–key, chipcard). Authorized entities only. • Person is something (biometrics, fingerprint etc.). Only Bob is allowed to enter here. We have to identify persons, processes and their roles. 43 45 Problem: Person/Process/Role ⇐⇒ String (1) Proof of Identity is Called Authentication Person identified by picture String identified by equality relation. 46 48 Proof of Identity: Links Person to a String Third party guarantees real identity. Has something: ID–card. 47 49 Proof of True Source is Called Authenticity -
Introduction
Introduction J. M. P. Alves Laboratory of Genomics & Bioinformatics in Parasitology Department of Parasitology, ICB, USP BMP0260 / ICB5765 / IBI5765 ● Introduction to computers and computing (UNIX) ● Linux basics ● Introduction to the Bash shell ● Connecting to this course’s virtual machine J.M.P. Alves 2 / 82 BMP0260 / ICB5765 / IBI5765 TuxThe Linux mascot “TUXedo”... By Larry Ewing, 1996 ...or Torvalds UniX Tux's ancestor J.M.P. Alves 3 / 82 BMP0260 / ICB5765 / IBI5765 Linux (Unix) & science Why so popular together? ● Historical reasons (programs made for Unix/Linux) ● Available on any kind of computer, especially powerful servers ● Works efficiently with humongous text files (head, tail, sort, cut, paste, grep, etc.) ● Complicated tasks can be made easy by concatenating simpler commands (piping) ● Creating new programs is easy – tools just one or two commands (or clicks) away (gcc, g++, python, perl) ● Stable, efficient, open (free software), no cost (software for free) J.M.P. Alves 4 / 82 BMP0260 / ICB5765 / IBI5765 What IS this Linux, anyway? J.M.P. Alves 5 / 82 BMP0260 / ICB5765 / IBI5765 Operating system J.M.P. Alves 6 / 82 BMP0260 / ICB5765 / IBI5765 An operating system is a collection of programs that initialize the computer's hardware, providing basic instructions for the control of devices, managing and scheduling tasks, and regulating their interactions with each other. J.M.P. Alves 7 / 82 BMP0260 / ICB5765 / IBI5765 You WhatsApp Android Phone J.M.P. Alves 8 / 82 BMP0260 / ICB5765 / IBI5765 You MUSCLE Linux Computer J.M.P. Alves 9 / 82 BMP0260 / ICB5765 / IBI5765 formerly: J.M.P. Alves 10 / 82 BMP0260 / ICB5765 / IBI5765 History J.M.P. -
Squinting at Power Series
Squinting at Power Series M. Douglas McIlroy AT&T Bell Laboratories Murray Hill, New Jersey 07974 ABSTRACT Data streams are an ideal vehicle for handling power series. Stream implementations can be read off directly from simple recursive equations that de®ne operations such as multiplication, substitution, exponentiation, and reversion of series. The bookkeeping that bedevils these algorithms when they are expressed in traditional languages is completely hidden when they are expressed in stream terms. Communicating processes are the key to the simplicity of the algorithms. Working versions are presented in newsqueak, the language of Pike's ``squint'' system; their effectiveness depends critically on the stream protocol. Series and streams Power series are natural objects for stream processing. Pertinent computations are neatly describable by recursive equations. CSP (communicating sequential process) languages1, 2 are good vehicles for implementation. This paper develops the algorithmic ideas and reduces them to practice in a working CSP language,3 not coincidentally illustrating the utility of concurrent programming notions in untangling the logic of some intricate computations on sequences. This elegant approach to power series computation, ®rst demonstrated but never published by Kahn and MacQueen as an application of their data stream system, is still little known.4 Power series are represented as streams of coef®cients, the exponents being given implicitly by ordinal position. (This is an in®nite analogue of the familiar representation of a polynomial as an array of coef®cients.) Thus the power series for the exponential function ∞ 1 1 1 e x = Σ x n / n! = 1 + x + __ x 2 + __ x 3 + ___ x 4 + . -
Uma Introdução À Computação: História E Ciência Editora Ixtlan - São Paulo – 2016
São Paulo – 2016 Copyright © Autores diversos Projeto gráfico: Editora Ixtlan Revisão: Eduardo Telmo Fonseca Santos Milena Montenegro Pereira Diagramação: Márcia Todeschini Capa: Gabriel Polizello Uma introdução à computação: história e ciência Editora Ixtlan - São Paulo – 2016 ISBN: 978-85-8197-510-8 1.Ciência da computação 2.história CDD 000 Editora Ixtlan - CNPJ 11.042.574/0001-49 - I.E. 456166992117 [email protected] – www.editoraixtlan.com DIREITOS PRESERVADOS – É proibida a reprodução total ou parcial, de qualquer forma ou por qualquer meio. A violação dos direitos de autor (Lei Federal 9.610/1998) é crime previsto no art. 184 do Código Penal. Sumário 1. Início da computação - 3 2. Software - 19 3. Representação da Informação - 27 4. Ciência da Computação é Ciência? - 35 5. Rede de Computadores - 37 6. Exercícios Complementares - 49 7. Bibliografia - 53 Cap´ıtulo 1 Início da computação Para entender os fundamentos da computação atual é preciso olhar para o passado e ver como essa disciplina/área foi fundada e como vem se desenvolvendo até a atualidade [5]. Uma das bases da computação é a Matemática. Desde os primórdios o ser humano percebeu a necessidade de desenvolver algo para auxiliá-lo nas mais diversas operações. Essa necessidade é a responsável pelo surgimento desde as máquinas de calcular até as mais diversas máquinas utilizadas no mundo todo. Em torno de 2600 anos a.C., surgiu um dos primeiros instrumentos manuais voltados para ajudar o homem a calcular quantias numéricas. Esse instrumento usado para representação dos números era o ábaco chinês, que apesar do tempo em que surgiu, ainda é comumente utilizado em certas localidades. -
Mount Litera Zee School Grade-VIII G.K Computer and Technology Read and Write in Notebook: 1
Mount Litera Zee School Grade-VIII G.K Computer and Technology Read and write in notebook: 1. Who is called as ‘Father of Computer’? a. Charles Babbage b. Bill Gates c. Blaise Pascal d. Mark Zuckerberg 2. Full Form of virus is? a. Visual Information Resource Under Seize b. Virtual Information Resource Under Size c. Vital Information Resource Under Seize d. Virtue Information Resource Under Seize 3. How many MB (Mega Byte) makes one GB (Giga Byte)? a. 1025 MB b. 1030 MB c. 1020 MB d. 1024 MB 4. Internet was developed in _______. a. 1973 b. 1993 c. 1983 d. 1963 5. Which was the first virus detected on ARPANET, the forerunner of the internet in the early 1970s? a. Exe Flie b. Creeper Virus c. Peeper Virus d. Trozen horse 6. Who is known as the Human Computer of India? a. Shakunthala Devi b. Nandan Nilekani c. Ajith Balakrishnan d. Manish Agarwal 7. When was the first smart phone launched? a. 1992 b. 1990 c. 1998 d. 2000 8. Which one of the following was the first search engine used? a. Google b. Archie c. AltaVista d. WAIS 9. Who is known as father of Internet? a. Alan Perlis b. Jean E. Sammet c. Vint Cerf d. Steve Lawrence 10. What us full form of GOOGLE? a. Global Orient of Oriented Group Language of Earth b. Global Organization of Oriented Group Language of Earth c. Global Orient of Oriented Group Language of Earth d. Global Oriented of Organization Group Language of Earth 11. Who developed Java Programming Language? a.