How to Use the Command Line to Run Ruby Scripts

How to Use the Command Line to Run Ruby Scripts Before really starting to use Ruby, you need to have a basic understanding of the command line. Since most Ruby scripts wont have graphical user interfaces, youll be running them from the command line. Thus, youll need to know, at the very least, how to navigate the directory structure and how to use pipe characters (such as |,   and ) to redirect input and output. The commands in this tutorial are the same on Windows, Linux, and OS X. To start a command prompt on Windows, go to Start - Run. In the dialog that appears, enter cmd into the input box and press OK.To start a command prompt on Ubuntu Linux, go to Applications - Accessories - Terminal.To start a command prompt on OS X, go to Applications - Utilities - Terminal. Once youre at the command line, youll be presented with a prompt. Its often a single character such as $ or #. The prompt may also contain more information, such as your username or your current directory. To enter a command  all you need to do is type in the command and hit the enter key. The first command to learn is the cd command, which will be used to get to the directory where you keep your Ruby files. The command below will change directory to the \scripts directory. Note that on Windows systems, the backslash character is used to delimit directories but on Linux and OS X, the forward slash character is used. C:\rubycd \scripts Running Ruby Scripts Now that you know how to navigate to your Ruby scripts (or your rb files), its time to run them. Open your text editor and save the following program as  test.rb. #!/usr/bin/env ruby    print What is your name? name gets.chomp puts Hello #{name}! Open a command line window and navigate to your Ruby scripts directory using the  cd  command. Once there, you can list files, using the  dir  command on Windows or the  ls  command on Linux or OS X. Your Ruby files will all have the .rb file extension. To run the test.rb Ruby script, run the command  ruby test.rb. The script should ask you for your name and greet you. Alternatively, you can configure your script to run without using the Ruby command. On Windows, the  one-click installer  already set up a file association with the .rb file extension. Simply running the command  test.rb  will run the script. In Linux and OS X, for scripts to run automatically, two things must be in place: a shebang line and the file being marked as executable. The shebang line is already done for you; its the first line in the script starting with  #!. This tells the shell what type of file this is. In this case, its a Ruby file to be executed with the Ruby interpreter. To mark the file as executable, run the command  chmod x test.rb. This will set a file permission bit indicating that the file is a program and that it can be run. Now, to run the program, simply enter the command  ./test.rb. Whether you invoke the Ruby interpreter manually with the Ruby command or run the Ruby script directly is up to you. Functionally, they are the same thing. Use whichever method you feel most comfortable with. Using Pipe Characters Using the pipe characters is an important skill to master, as these characters will alter the input or output of a Ruby script. In this example, the  Ã‚  character is used to redirect the output of test.rb to  a text file  called test.txt instead of printing to the screen. If you open new test.txt file after you run the script, youll see the output of the test.rb Ruby script. Knowing how to save output to a .txt file can be very useful. It allows you to save program output for careful examination or to be used as input to another script at a later time. C:\scriptsruby example.rb test.txt Similarly, by using the  Ã‚  character instead of the  Ã‚  character you can redirect any input a Ruby script may read from the keyboard to read from a .txt file. Its helpful to think of these two characters as funnels; youre funneling output to files and input from files. C:\scriptsruby example.rb Then theres the pipe character,  |. This character will funnel the output from one script to the input of another script. Its the equivalent of funneling the output of a script to a file, then funneling the input of a second script from that file. It just shortens the process. The  |  character is useful in creating filter type programs, where one script generates unformatted output and another script formats the output to the desired format. Then the second script could be changed or replaced entirely without having to modify the first script at all. C:\scriptsruby example1.rb | ruby example2.rb The Interactive Ruby Prompt One of the great things about Ruby is that its test-driven. The interactive Ruby prompt provides an interface to the Ruby language for instant experimentation. This comes in handy while learning Ruby and experimenting with things like regular expressions. Ruby statements can be run and the output and return values can be examined immediately. If you make a mistake, you can go back and edit your previous Ruby statements to correct those mistakes. To start the IRB prompt, open your command-line and run the  irb  command. Youll be presented with the following prompt: irb(main):001:0 Type the  hello world  statement weve been using into the prompt and hit Enter. Youll see any output the statement generated as well as the return value of the statement before being returned to the prompt. In this case, the statement output Hello world! and it returned  nil. irb(main):001:0 puts Hello world! Hello world! nilf irb(main):002:0 To run this command again, simply press the up key on your keyboard to get to the statement you previously ran and press the Enter key. If you want to edit the statement before running it again, press the left and right arrow keys to move the cursor to the correct place in the statement. Make your edits and press Enter to run the new command. Pressing up or down additional times will allow you to examine more of statements youve run. The interactive Ruby tool should be used throughout learning Ruby. When you learn about a new feature or just want to try something, start up the interactive Ruby prompt and try it. See what the  statement  returns, pass  different parameters  to it and just do some general experimenting. Trying something yourself and seeing what it does can be a lot more valuable than just reading about it!

Assignment Essay Example | Topics and Well Written Essays - 500 words - 46

Assignment - Essay Example This is called differentiation. Marketing lets business leadership find a valuable or innovative feature of a product or service and then promote to customers why this product should be purchased over similar competitor products. Marketing is also about cost controls using different metrics to measure whether a promotional campaign is meeting with success. For example, it might be discovered through market research that making a product costs the organization far too much with the operations budget. This would have an impact on the price to customers so that the company does not lose money in production. Marketing activity lets a business see all of its expenses and make changes to build a more productive manufacturing system. Controls in business strategy are very important to be successful and discover if the business can be more effective. The question as to whether or not marketers should continue to market cigarettes is an ethical issue. If there is consumer demand for the product and it is considered a legal substance, there really is no reason why marketers cannot continue to promote the product. Consumer safety is a big issue in marketing and general business, but in the case of cigarettes, it is consumers that are responsible to make decisions that are good for their health status. Governments and many different special interest groups have provided society with scientific knowledge about the dangers of cigarettes. There are likely few people in the world today, both young and old, that are unaware that cigarettes cause cancer and other serious illnesses and health problems. If consumers continue to buy the product, it is not likely because of tobacco company promotions, but because they enjoy consuming the product. Ethics differ from culture to culture so there is no one universal set of beliefs and values that should be forced on cigarette marketers. Then the answer is yes,

Application of the principles of health and safety to the operating Essay

Application of the principles of health and safety to the operating theatre environment - Essay Example The operating department practitioner (ODP) should be alert to any fears or apprehensions expressed by the patient and transmit such information to the surgeon (Lyons, 1997). The patient and his family should be encouraged to communicate freely with the physician. The preparation and care of the patient before surgery has one major goal to promote the best possible physical and psychological state of the patient prior to surgical therapy. To achieve this goal, the patient’s individual needs must be ascertained and his strengths and limitations evaluated. A plan of care can then be developed to assist the patient in adjusting physically and emotion ­ally to the surgical experience. Preparation for surgery should begin as soon as the patient is told that an operation is necessary. The anticipation of any surgical procedure will result in an emotional reaction  ­of some kind, and much can be done to allevi ­ate fears prior to admission as well as during hospitalization. The patient’s reaction will depend on many factors, including his person ­ality structure and his pattern of reaction to stressful events in the past. A surgical operation is a stressful situation in which the patient may believe that he is in danger of acute pain, serious damage to the body, disability, and death. In addition there is a fear of the unknown. This can be compli ­cated by fear of anesthesia or fear of separa ­tion from activities, family, and friends. The average patient also worries about financial problems, family responsibilities, and em ­ployment status. Anxiety will usually increase as the time for surgery draws near. The ODP can assist the patient, his fami ly, and surgical personnel by listening to the patient and helping him to verbalize his fears. Often the patient only wants the opportunity to acknowledge his fears to a caring, under ­standing, and accepting person (Saylor, 1975). The evening before surgery the

Chapter 21 notes- the kite runner Essay Example for Free

Chapter 21 notes- the kite runner Essay Amir visits his old house in Kabul and the hill north of Baba’s house- The city is now completely unfamiliar to Amir, and he looks at it almost as a tourist Amir looks outside his bedroom window and remembers looking out of it when watching Hassan and Amir leave. â€Å"Twenty-five years earlier, I had stood behind that same window, thick rain dripping down the panes and my breath fogging up the glass. I had watched Hassan and Ali load their belongings into the trunk of my father’s car† -Amir Characters involved: Amir Farid Hassan- Amir discusses their good memories in the yard of Baba’s house and up at the pomegranate tree on the hill. â€Å"Amir and Hassan. The Sultans of Kabul†- still carved into the pomegranate tree. A man and woman were executed on the soccer oval in front of all the spectators Characters involved: Taliban (Islamic radicals) Amir Farid Woman and man both killed by rocks â€Å"And they call themselves Muslims† -Farid â€Å"Mord? Mord? Is he dead? † -Amir â€Å"Every sinner must be punished in a manner befitting his sin! †- Cleric at the stadium. This part of the text gives evidence that the Taliban are brutal, have no sympathy and are murderers. The Taliban say they are obeying God. Meeting arranged to meet with the Taliban that afternoon. Characters involved: Farid- asks for Amir Taliban official Symbols Pomegranate tree â€Å"Then I went looking for the abandoned cemetery. It didn’t take me long to find it. It was still there, and so was the old pomegranate tree. †- Amir â€Å"I stood under it, remembered all the times we’d climbed it, straddled it’s branches, our legs swinging, dappled sunlight flickering through the leaves and casting on our faces a mosaic of light and shadow. The tangy taste of pomegranate crept into my mouth. † -Amir The ruined, dead tree serves as a symbol that the city Kabul that Amir knew was now dead. Environment- Kabul- *Desolate. *Ruined *Dusty *Abandoned *Sun-dried Amir’s house *Surrounded by weeds *Rusty â€Å"The Wall of Ailing Corn was still there, though I saw no corn, ailing or other-wise, along that wall now. †-Amir Paint peeled off â€Å"The house was far from the sprawling white mansion I remembered from my childhood. It looked smaller. † -Amir â€Å"Like so much else in Kabul, my father’s house was the picture of fallen splendour. † -Amir â€Å"I wanted to step into the foyer, smell the orange peel Ali always tossed into the stove to burn the sawdust. Sit at the kitchen table, have tea with a slice of naan, listen to Hassan sing old Hazara songs. † -Amir.

It’s the End of the Worldand I Feel Fine Essay -- essays papers

It’s the End of the Worldand I Feel Fine It’s the End of the World†¦and I Feel Fine! (The role of intellectuals in the creation and justification of nuclear weapons.) In Fail Safe and Dr. Strangelove, Or: How I Learned to Stop Worrying and Love the Bomb, Sidney Lumet and Stanley Kubrick question the relationship between technology and humanity by emphasizing mankind’s tendency to create machines that cannot be adequately controlled. By blatantly revealing the absurdity of game theory (Mutual Assured Destruction as a reasonable deterrence for nuclear war), both directors call into question the dominant pro-Cold War American ideology. One of the most quintessential aspects of this ideology includes the drive for constant technological advance and strategic superiority. Without the brainpower of the scientists and intellectuals who dedicated their lives to the extension of technological power and the study of international conflict, the Arms Race would certainly not have been possible. These academics not only became the architects of atomic weapons but they were also faced with justifying the use of these nuclear bombs, and creating a th eoretical framework within which nuclear warfare might be appropriately (and rationally) conducted. Within this context, one noteworthy parallel between Fail Safe and Dr. Strangelove is the existence (in both films) of a single intellectual genius that actively perpetuates the â€Å"science† of nuclear advancement and strategy. Indeed, through the characterizations of Professor Groeteschele and Dr. Strangelove, both Lumet and Kubrick examine the prominent role of intellectuals (both scientists and theorists) in the creation and justification of nuclear warfare. Ultimately, both Lumet and Kubrick reveal the problems with relying solely on science and mathematics to resolve international conflict, thus suggesting that modern warfare requires a more humanistic, ethical definition of right and wrong. Both Fail Safe and Dr Strangelove serve as moralizing responses to the dominant American Cold War culture, rhetoric, and political policy. In his article titled â€Å"Dr. Strangelove (1964): Nightmare Comedy and the ideology of Liberal Consensus,† Charles Maland identi fies the dominant American cultural paradigm (during the Cold War) as â€Å"the Ideology of the Liberal Consensus.† Maland maintains that the Ideology of the ... ...ocosm of possible nuclear disasters, both directors choose to include a character that embodies the contemporary ‘nuclear intellectual.’ Indeed, scientists and theoreticians (like Groeteschele and Strangelove) played a prominent role in defining and perpetuating the new Cold War culture. These academics not only became the architects of nuclear bombs but they were also faced with creating a viable theoretical framework within which the use of these weapons would be both recommended and justified. However, both Kubrick and Lumet suggest that in order to apply their brilliance towards mass destruction and death, intellectuals must give up a portion of their humanity, becoming increasingly more like the devices they create and defend. The mutual catastrophes that occur in Fail Safe and Dr. Strangelove show the inevitability of human weakness and scientific fallibility. Through the development of Professor Groeteschele and Dr. Strangelove, both Lumet and Kubrick illustra te the catastrophic possibilities of relying solely on science and mathematics to resolve international conflicts. Ultimately, modern, high stake warfare requires a more humanistic, ethical code of right and wrong.

Ka Ching Tone Assignment

In Margaret Atwood’s Ka-Ching!, the dominant tone of the passage is nostalgic and contemplative. When Atwood describes her first job, working for a small hotel coffee shop, she refers to it as being a clean, well-lighted, with booths, counters and waitresses. She is looking back on what seemed to be a poor experience.The basis of the Machiavellian characteristics was to do whatever it took to gain power and maintain that power. During the time of William Shakespeare being a ruler had nothing to do with being a good person, nor did it ever mean doing the right thing. The characteristics that Claudius possess are that he manipulates people, he is unapologetic, and extremely selfish.The dominant tone of the passage is cynical and satirical.The idea that a baby or child could be used as a snack is cynical and satirical. Swift presents his point of view on cannibalism as if it were something completely normal, ignoring the fact that it is taboo, and not socially acceptable. When re ading, we are able to understand that eating children would never happen, but due to his use of diction, a sarcastic and a cynical tone is used. With use of proper connotative diction the author allows us to understand the terrible conditions in Ireland and reveals the dominant tone. â€Å"I can think of no one objection that will possibly be raised against this proposal, unless it be urged that the number of people will be thereby much lessened in the kingdom.† It may seem that the narrator may be serious when proposing his solution, but we are able to detect plenty of cynicism.â€Å"For this kind of commodity will not bear exportation, the flesh being of too tender a consistence to admit a long continuance in salt, although perhaps I could name a country which would be glad to eat up our whole nation without it.† An awful lot of extremity is  portrayed when Jonathan Swift explains how humans could possibly be exported to other countries in order to be sold and eate n. This demonstrates plenty of sarcastic diction. The denotation of cynical is showing the belief that a person could be solely motivated by selfish concerns.In this passage Swift is able to support his points of view towards the conditions of Ireland with valid reasoning although not realistic. The denotation of sarcasm is not necessarily ironic, but rather a rude or bitter remark toward a thought or point of view. Again, Swift uses sarcastic diction in a connotative way in order to explain to the reader that eating and selling humans is a valid option to better the country and the citizens.

The Trail of Socrates and the development of Western...

THESIS STATEMENT Socrates was accused of corrupting the youth of Athens and sentenced to die for his beliefs. He accepted this punishment because he truly thought what he believed was right. PURPOSE STATEMENT By conducting research and examining various sources, The trail of Socrates proved to be an important part in history, impacting the development of Western Philosophy and allowing the beliefs of Socrates to live on to this day. INTRODUCTION â€Å"The death of Socrates has had a huge and almost continuous impact on western culture† (Wilson 1). Socrates life, trial, and death are all important parts of history. Socrates was a philosopher in Athens who believed in using reason to explain different aspects of life. During his†¦show more content†¦Throughout his entire life, to the moment he died, he did his best to help the people around him. He wanted them to think and make correct moral decisions. â€Å"Athens, one of the world’s earliest democracies, raised Socrates, educated him and finally sentenced him to death, having found him guilty of religious unorthodoxy and corrupting the young† (Wilson 2). Socrates was born in Alopece, a district of ancient Athens. He was born of Sophroniscus and Phaenarete. He married Xanthippe and they had three children. We do not have any writing that Socrates wrote himself. Therefore, our major sources for Socrates are Plato, Xenophan, and Aristophanes. Plato was a student of Socrates. However, not everything he wrote about Socrates can be taken literally. Plato used Socrates as a figure to voice different viewpoints. Everything Plato said about Socrates may not be completely true. Xenophan defended the accusations that were being held against Socrates. In the Apology, he describes Socrates mindset. This gives us an understanding of how Socrates stood up for his beliefs to the point where it cost him his life. Aristophanes wrote a play entitled The Clouds. Socrates was a character in this fictional comedy. The Clouds portrays Socrates as corrupting the youth of Athens and not properly venerating the gods of Athens. Socrates did not take offense to this, as comedies are meant just as entertainment.Show MoreRelatedThe Political Philosophy Of Niccolo Machiavelli And Socrates1444 Words   |  6 PagesAmong the most well-known and notorious philosophers, Niccolo Machiavelli and Socrates laid the groundwork f or western political philosophy and modern day politics. Though both lived through times of political transition and war, the fragility of their politics, violence of their wars, and the leaders they lived under influenced the development of their differing ideologies about the governing of principalities. From Machiavelli’s experience, came, â€Å"The Prince,† a guidebook about the importance ofRead MoreQuestion and Correct Answer7042 Words   |  29 Pages | | Along which river did Indian civilization develop?Answer | | | | | Selected Answer: |   Ã‚   Indus | Correct Answer: |   Ã‚   Indus | | | | | ï‚ · Question 27 2 out of 2 points | | | Why was the Silk Road so important in Chinas development?Answer | | | | | Selected Answer: |   Ã‚   It spurred the cultural interchange between East and West, India and China | Correct Answer: |   Ã‚   It spurred the cultural interchange between East and West, India and China | | | | | ï‚ · QuestionRead MoreContemporary Issues in Management Accounting211377 Words   |  846 Pagesinterested in gaining direct insights into specialized management accounting areas will Wnd this book to be an especially valuable reference source. Established Welds cannot grow in the absence of committed Wgureheads who tirelessly contribute to their development. One individual who has contributed immensely to management accounting thought and practice over the course of more than four decades is Michael Bromwich. Bromwich, who is about to retire as CIMA Professor of Accounting and Financial ManagementRead MoreLogical Reasoning189930 Words   |  760 Pagesupdated: April 26, 2016 Logical Reasoning Bradley H. Dowden Philosophy Department California State University Sacramento Sacramento, CA 95819 USA ii iii Preface Copyright  © 2011-14 by Bradley H. Dowden This book Logical Reasoning by Bradley H. Dowden is licensed under a Creative Commons AttributionNonCommercial-NoDerivs 3.0 Unported License. That is, you are free to share, copy, distribute, store, and transmit all or any part of the work under the following conditions: