Wednesday, March 12, 2014

using SSH in Linux Systems


There are a couple of ways that you can access a shell (command line) remotely on most Linux/Unix systems. One of the older ways is to use the telnet program, which is available on most network capable operating systems. Accessing a shell account through the telnet method though poses a danger in that everything that you send or receive over that telnet session is visible in plain text on your local network, and the local network of the machine you are connecting to. So anyone who can "sniff" the connection in-between can see your username, password, email that you read, and commands that you run. For these reasons you need a more sophisticated program than telnet to connect to a remote host.

SSH, which is an acronym for Secure SHell, was designed and created to provide the best security when accessing another computer remotely. Not only does it encrypt the session, it also provides better authentication facilities, as well as features like secure file transfer, X session forwarding, port forwarding and more so that you can increase the security of other protocols. It can use different forms of encryption ranging anywhere from 512 bit on up to as high as 32768 bits and includes ciphers like AES (Advanced Encryption Scheme), Triple DES, Blowfish, CAST128 or Arcfour. Of course, the higher the bits, the longer it will take to generate and use keys as well as the longer it will take to pass data over the connection. 

Open you Linux Terminal ( Ctrl + Alt + T)


ssh chitrankdixit@insomnia247.nl


after the screen will prompt for the user password associated with that Shell account


Lydia on Insomnia 24/7 network.

chitrankdixit@insomnia.nl's password: 



The following video will show you how to use the shell access. please have a look.




Friday, December 20, 2013

Course to watch out Power Searching with Google: 1 Introduction

Power Searching with Google:
The following course is not related to Computer Programming , Software Development and Theoretical aspects of Computer Science. The following course offered by Google is to understand the seen yet unseen power of Google Search. Please have a look at the details. I am posting the Unit 1 so as to have a quick review of the Google Search and services offered, I hope you would find it good and join to enjoy more units ahead at the source below.


Lesson 1.1: Instructions for taking this course



The videos for this class are presented by Dr. Dan Russell, a research scientist at Google. In the text versions you will find parallel information, with illustrations, in case you prefer learning through the written word.

Dan’s research demonstrates that while Google is really easy to use, many people do not use it to its full advantage. Through this course, we hope to help you become even faster at finding what you need.

The course is composed of six classes:

  • How Google works
  • Extending what you know
  • Advanced techniques
  • Finding facts faster
  • Checking your facts
  • Putting it all together

Each class consists of five lessons. Within each lesson there is a short video followed by a hands-on activity that lets you try the techniques discussed. The activities are not required, but we recommend that you use them as an opportunity to apply what you see in the video. Be sure to also read the additional Search Tips at the top of each activity page.

The course includes two assessments, which are required if you want to earn the certificate of completion. There is a mid-term after Class Three, worth ⅓ of your final score, and another assessment after Class Six, worth ⅔ of your final score. You must earn a 70% overall score to pass. Because the goal is for you to be able to find what you need even more efficiently and effectively, you can take the two assessments as many times as you want. Only your most recent score will count.

As you go through the class, you will hear about a variety of ways to use Google to find information. As you move among Google products, you will frequently have the opportunity to search, and the techniques and ideas that you learn in this course often apply to them as well.



Lesson 1.2: Filtering by color



NOTE: When you see square brackets ([ ]), they denote a search box. That is, if you see [golfcross rules], then you type only the words golfcross rules into the search box on Google—you do not type the square brackets into Google. It would look like this:




Searching on Google often starts with entering a query.

A query is the set of words you type into the search box to tell Google what you want to find.

Once you enter a query and get results, you can consider whether you want to focus the results in some way.

One really fun way to focus is to search in Google Images and filter results by color.

For example, you can do a search in Google Images for [fossils]. Once you have your results, you can look on the left-hand side of the screen and locate these rows of colored boxes:


Using these boxes, you can filter to find images of a specific color. So, if you want images that are primarily grey in color, you can click on the grey color box:



Not only does this technique select images that are grey in color, in the picture above you can see that the color actually implies context: these fossils are all in grey stone.

By clicking on different color boxes, you can see fossils embedded in different kinds of rock:




Color filtering is so compelling because you can find images based on information that might not be included in the text of the page. The web pages containing these images may not say in what kind of rock the fossils are embedded, but you might have the expertise tell by its color. In this way you can use color to search for information that is only available to the eye.

The colors in an image often imply information you can not easily search for with words.

Another example is an image search for [tesla], where the general results represent a number of different ideas:






Clicking on purple selects for images of electricity arcing from a transformer called a Tesla Coil:



And clicking on the black and white option—above the color boxes in the left-hand panel—helps select images of Nikola Tesla, the inventor of the Tesla Coil:



You can focus on even more precise results when you find an image you like. Mousing over a particular image makes a larger version pop up, which allows you to access the Similar link:






You can take color filtering for context one step further.
If you modify your query to [tesla coil]:






With diagrams you can also mouse over an image to use the Similar link. You could use this filter, for example, if you specifically wanted to get more schematic diagrams:




Try the activity on color filtering. 

Lesson 1.3: How Search Works



This lesson features a video by Matt Cutts, an engineer at Google. It demonstrates how spiders work: how they crawl the web, collect information, and pull it all together to provide an index Google uses every time you do a search.

Here's Matt Cutts explaining how search actually works:




Matt Cutts: Hi. My name is Matt Cutts. I am an engineer in the Quality group at Google, and I'd like to talk today about what happens when you do a web search. The first thing to understand is, when you do a Google search, you aren't actually searching the web. You're searching Google's index of the web, or at least as much of it as we can find.
We do this with software programs called spiders. Spiders start by fetching a few web pages, then they follow the links on those pages and fetch the pages they point to; and follow all the links on those pages, and fetch the pages they link to, and so on, until we've indexed a pretty big chunk of the web; many billions of pages stored on thousands of machines.

Now, suppose I want to know how fast a Cheetah can run. I type in my search, say [cheetah, running, speed] and hit return.

Our software searches our index to find every page that includes those search terms. In this case, there are hundreds of thousands of possible results.

How does Google decide which few documents I really want?

By asking questions; more than two hundred of them. Like:

  • How many times does this page contain your key words?
  • Do the words appear in the title? In the URL (web address)?
  • Do the words appear directly adjacent?
  • Does the page include synonyms for those words?
  • Is this page from a quality website? Or is it low quality, even spammy? What is this page's PageRank? That's a formula invented by our founders, Larry Page and Sergey Brin, that rates a webpage's importance by looking at how many outside links point to it, and how important those links are.

Finally, we combine all those factors together to produce each page's overall score and send you back your search results, about half a second after you submit your search.

At Google, we take our commitment to delivering useful and impartial search results VERY seriously. We don't ever accept a payment to add a site to our index, update it more often, or improve its ranking.

Sometimes, along the right, and at the top, you'll see ads.



We take our advertising business very seriously as well. Both, our commitment to delivering the best possible audience for our advertisers, and to strive to only show ads that you really want to see.

We're very careful to distinguish your ads from your search results. And we won't show you any ads at all if we can't find any we think will help you find the information you're looking for. Which in this case, a cheetah's top running speed, is more than sixty miles an hour.

Thanks for watching. I hope this makes Google a little more understandable.

Give the activity a try!


Lesson 1.4: The art of keyword choice



In the last lesson, engineer Matt Cutts talked about how search works. How do you apply that knowledge to choose better words to use in your query?

Sometimes you have to try a couple of different queries to focus in on the information you want, trying different combinations of keywords. Keywords are the most important words in your idea or question—they tell the search engine what you are seeking. They can also be called search terms.

When you get ready to type in a query, think for a moment about what you really want to find. One way to do that is to consider what words you think will appear on the page that would have the perfect answer. Imagine that page for a moment. How would someone else write about it? That is actually an important skill: how you put yourself in the mindset of the author who wrote your perfect page?


For example, if you search Google for information about your kid who broke an arm, what kind of results would you get for a query like [busted arm]? 

Lesson 1.5: Word order matters



The previous lesson focused on choosing words to use in your query. This lesson concentrates on the way you enter those words, and how those choices impact your results.

1. Every word matters

As you saw in the last lesson, every word you enter into a query has the potential to impact your results. Consider the difference among your results for [who], [a who], and [the who].

If you search for [who], what do you expect to see?


Lesson 1.6: Finding text on a web page



Have you ever needed to locate words on a page efficiently? Suppose you want to find your time in the local 8K race. It’s easy to find the page that contains the information, but what do you do then?

One option is the Find feature, using Control-F (Command-F on Mac), to find a piece of text on a web page. Unlike searching, which looks across a number of web pages to find which of the pages contain certain words, Control-F/Command-F looks within the text of a single page to find precisely where that word is located.

You can try out Control-F/Command-F on any webpage. For example, if you want to know where Mumbai, India ranks among the most populous cities in the world, you might search for [most populous cities world] and pick one of the pages that come up. Next, your task is to locate the word Mumbai on the page.

Find the Control key (Command key on Mac). While holding that key down, also press the F key. A find box will open, and you can enter the word Mumbai to locate it on the page.

Where exactly your find box opens on the screen varies, depending on which browser you are using:

  • Firefox: Bottom left corner of the screen. You can type in the word you want to find and use the next and previous buttons to go forward or backward in the document. You can click on the button that says "highlight all" and that will put a yellow background on all instances of that text anywhere in the document.
  • Safari: Upper right corner of the screen. If you type a word on this page, you can see how many matches there are, and you can also use forward and back buttons. You can use the "Enter" ("return" on Mac) key to go forward to the next search as well.
  • Chrome: Upper right corner of the screen. You can see how many instances of that word there are.
  • Internet Explorer: Opens in a pop-up box in the middle of the screen, or underneath the address bar across the top of the screen.
  • iPad (Safari): When you are viewing a webpage, click on the search box in the upper right corner of the screen. The find box appears on the top right side of the on-screen keyboard.
  • Android tablet: Select menu in top right, then select "Find on page" in the menu.

This feature allows you to review a long document quickly.

When you are using the Find feature, consider what word to use. For example, you wanted to know which games Scotland played in cricket in the month of August 2010. If you had a list of sporting events in August 2010 and used the Find feature to look for [scotland], you would need to scroll through 26 occurrences of the term to find the ones related to cricket. Alternately, you might chose to find the word [cricket] on the page, instead. There are 29 occurrences of cricket, but since the word "cricket" is always at the head of each section, it might be a faster process.

Please note that at this time, there is no easy way using Control-F/ Command-F to find two words near each other if they are not adjacent.

Why do you need to know this? The big reason is that it can really speed up finding what you want. In our studies we've found that it cuts the time people need to locate information in regular web search by about 12%. When we carried out this study, we found that only 10% of all searchers knew about using Control-F/Command-F.

Please use the activity to try out the Find feature for yourself.

Wednesday, December 18, 2013

Teach Yourself Programming in 10 years : Summary

The following article by Peter Norvig (Google Director of Research) says that you would need atleast 10 years to learn the programming in a particular language from the tip to the end. Learning programming language and its nature is not a big task but in the quick way to learn something we lose the stuff that we would have learnt from our success and failures with the Programming language.

There are lots of books available in the market with the title "Teach yourself Java in 7 days" and similarly "Teach yourself  Bla Bla Bla in 5 hours". But these books would not increase your knowledge. Because

Let's analyze what a title like Learn C++ in Three Days could mean:
  • Learn: In 3 days you won't have time to write several significant programs, and learn from your successes and failures with them. You won't have time to work with an experienced programmer and understand what it is like to live in a C++ environment. In short, you won't have time to learn much. So the book can only be talking about a superficial familiarity, not a deep understanding. As Alexander Pope said, a little learning is a dangerous thing.
  • C++: In 3 days you might be able to learn some of the syntax of C++ (if you already know another language), but you couldn't learn much about how to use the language. In short, if you were, say, a Basic programmer, you could learn to write programs in the style of Basic using C++ syntax, but you couldn't learn what C++ is actually good (and bad) for. So what's the point? Alan Perlis once said: "A language that doesn't affect the way you think about programming, is not worth knowing". One possible point is that you have to learn a tiny bit of C++ (or more likely, something like JavaScript or Flash's Flex) because you need to interface with an existing tool to accomplish a specific task. But then you're not learning how to program; you're learning to accomplish that task.
  • in Three Days: Unfortunately, this is not enough, as the next section shows.
Please read out the full article by Peter Norvig here: http://norvig.com/21-days.html



The following Article has been translated in 24 languages so far (don't say Google Translate would do the job , remember the English (U.K.) and English (U.S.A.) is not the same so as Spanish (in Mexico) and Spanish (in Spain)). This is also available in Hindi please have a look and see the Importance of Learning the Programming Language with not just days , hours or months but it is a long journey for years.
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