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 Disk Management  Disk is a secondary storage device that is used to store data.  The external devices such as hard disk, magnetic disks and floppy disks stores data in the sectors.  These devices provide the data to user programs by means of I/O requests.  Disk Management is an important function of operating system and includes disk buffering and management of swap area and disk cache.  Disk Structure  Disks provide a means to store a large amount of information for modern computer.  A disk is usually divided into tracks, cylinder and sectors.  Below fig shows the various components of a disk system.  Data is stored on a series of magnetic disks called platters. These disks are connected by a common spindle that spins at very high speed (some spindle rotate at speeds of 3600 revolutions per minute).  The two surfaces of a platter are covered with a magnetic material similar to that on a magnetic tape. Information is recorded mag...

 Linux Operating System  Inserting Files :  Let us assume that two people have worked on a project. To cut down on time they have split up writing the report. To combine the finished reports together, they can use the facility provided by 'vi' to insert files into the currently open the document. This can be done by opening the file that contains the first part of the report and positioning the cursor at the end of the report file. After this is done, the 'vi' mode has to be switched to command mode by pressing the 'esc' key.  1. Create a file as first report and insert lines as shown below, save it by pressing wq at the command prompt.  [user1 @linux-mac user1]$cat>>first_report  line1 of report 1 line2 of report 1 line3 of report 1 2. Create a file as second report and insert lines as shown below, save it by pressing by wq at the command prompt.  [user1 @linux-mac user1]$cat>>second_report This is the second report  Line1 of rep...

 Introduction  An editor is a program used to edit files. Files can be of different types such as : Text Files, Graphic Files etc. Depending upon what they contain.   An editor is a program used to edit files that contain text only. For e.g. : A letter of source code of a program.  Linux offers editors such as 'PICO', 'VI' and many others.  The 'VI' Editor  The vi (visual) editor is a full screen editor. This means that you will be able to position the cursor to the location in the file where you want to place the changes and addition.  The changes that you make will reflect on the screen. Vi will work with many different types of terminals if u set the terminal type correctly before invoking the editor.  Vi editor is one of the most powerful and earliest editor available in Linux and Unix environment.  VI Basic Concepts  The three models of operation in vi are :  1. Command Mode   2. Insert or Input Mode  3...

 FILTERS  A filter is a program that reads data from the output of another program or the standard input, processes it in some way, and sends the processed data to standard output or to another program.  There are many filters that are available in linux.  'wc' Command  'wc' stands for 'word count'. The 'wc' command counts the 'lines' , 'words' and 'characters' in a specified file.  Syntax : wc [options]  [filename]  [user1 @linux-mac user1] $ wc names     1          5          22            names  Option                  Purpose             -c          Prints only the character count  -w         Prints only the word count   -l           Prints only the line count  's...

 Editors  In Unix, a text file is created and modified by a program, called text editor or simply editor. Unix operating system also comes with several editors.  Types Of Editors : LINE EDITORS : The Unix editors that edit processes one line at a time are called line editors. Common example are ED and EX.  SCREEN EDITORS : Editors that makes use of whole screen for editing or processing more than one line at a time are called screen editor. With screen editor you can display and edit many lines by giving a single command. Example Vi.  Various Commands of Linux  Listing of files  '1s' command lists the files in the specified directory.  Syntax : 1s[options]  At the command prompt type 1s  [user1 @linux-mac user1]$ 1s The screen will look like this, because we have not created any directory or file.  [user1 @linux-mac user1]$ 1s [user1 @linux-mac user1]$ Find Out Where You Are  The command used for this purpose is 'pwd'. Thi...

 Linux Operating System Linux is an operating system that is modeled on UNIX operating system and is advanced version of UNIX.  Linux was originally developed by Linus Torvalds at the University of Helsinki.  It was initially developed for Intel 80386 processor based IBM compatible personal computer.  Over the years Linux has been ported to other platforms based on different processor architectures such as DEC (now HP) Alpha, Sun, SPARC, Motorolla etc.  Linux is an open source product and its source code is easily available.  It is a multi user system which means that more than one user can work at the same computer system at the same time.  It also supports multi - tasking that means more than one program can be made to run at the same time.  These important characteristics have helped it gain widespread acceptance among a large variety of users.  The various features of Linux are :-  Portability  The Strong thing about Linux...

 Meaning of Adventure Sports :-  Adventure sports have been around for thousands of years, only they haven't exactly been considered sports. The words 'Adventure Sports' reveal the meaning themselves. They are thrilling and adventurous. They give a participant a brush with death and a feeling of both fear and pleasure. Adventure sports range from extreme water sports like river rafting to land activities like Rock climbing, Mountaineering etc. These activities are addictive and peaceful to some and horrifying for others.  According to sports adventure website, '' Adventure sports have been best defined as outdoor sports or activities in which the participant competes in a natural environment more against themselves than against others.'' Classification of Adventure Sports Activities  Adventure sports activities are broadly classified in 3 categories : (a) Land based Adventure activities  (b) Water based Adventure activities (water sports)  (c) Air or A...

 History / Introduction  Swimming is considered as an ancient game. Men must have learnt swimming from animals. Swimming is not only a game but it is a life saver and a major technique in battle field. The first book on swimming was written by Prof. Nicolous of Germany in 1538. The first swimming club was established in 1860. Serpentene club has the honour of being the oldest club. When the Olympic games were restarted in 1896, the men's swimming was included in it. In 1912, the first woman's competition were included in Olympic games. India took part for the first time in swimming competition in the 1928 Amsterdam Olympics. Swimming Association of India was formed in 1940. Swimming was included in the Asian games in 1951 which were held in New Delhi.  Tips to Remember : 1. Length of Swimming pool is 50 metre.  2. Width of the swimming pool is 21 metre to 25 metre.  3. Depth of the swimming pool is more than 1.80 metre.  4. Number of lanes in swimming ...

  * THE SEVEN LAYERS OF OSI MODEL OF MODEL ARE :-  1. Physical Layer  2. Data Link Layer  3. Network Layer  4. Transport Layer  5. Session Layer  6. Presentation Layer  7. Application Layer  1. Physical Layer :-  This is the lowest layer in the model.  This layer is responsible for activating, maintaining and deactivating a physical circuit between two end systems.  It specifies the mechanical (physical) and electrical characteristics of interfaces and connections composing the network.  It deals with mechanical, procedural, electrical and functional characteristics of transmission media. Thus it can be think of as a hardware layer.  The layer exists as chips, network adapters (PCB's) and cables .  The actual data transfer takes place between physical layer of sender and receiver stations.  The physical layer is simply responsible for sending bits (bits are binary 1's and 0's of a digital communication)...

History / Introduction  Bocce Ball has been evolving for thousands of years. The basics of the game can be traced back to games that were played in Egypt around 5000 BC when people first began settling along the Nile Delta. Records dating to the 3rd century BC also show the popularity of a Bocce like game with Roman soldiers. As the Roman Empire spread, this game was introduced throughout the European continent, Asia and North Africa.  Bocce Ball is one of the oldest of all lawn or yard games. It was Giussepi Garibaldi, who, while unifying and nationalizing Italy, popularized the sport as it is known as today. Bocce frequently lost and gained popularity throughout the ages. In 1896, during a resurgence of popularity, the first Bocce Olympied was held in Athens, Greece. Bocce has been a part of international sports ever since.  Bocce has seen many changes throughout the ages. It has evolved from being a crude sport played with rounded rocks, or even coconuts to the mo...

 History / Introduction  Wrestling is an attacking game and it is possibly as old as human beings. In our country, the Wrestling is associated with Bheema, who was a brother of Pandavas.  Wrestling is also known as 'Bhalwani'. It is an ancient game. In this game the players are classified according to weight. It was initially played by men only, but now it is played by women also.  Latest Rules of Wrestling : Start of Bout : Referee stands in the middle of the mat and calls both the wrestler near him. He shakes hands with them and examines their costumes. He also assures that no wrestler should have any lubricant on his body. He examines if their nails are properly cut and they must have a handkerchief.  Then the players shake hands and the Wrestling starts with the whistle of the referee.  End of Bout : The Wrestling ends in following conditions : (i) By fall.  (ii) At the time when a player is injured.  (iii) At the end of time.  The W...

  REFERENCE MODELS OF NETWORK  INTRODUCTION :-  The problem of getting a computer of one brand to accept the data created by another manufacturers machine has confirmed users of these machine since their earlier days.  At that time the only practical way around this barrier was to retype the data from the computer into the second.  This is very time consuming procedure and has the chance of lot of errors.  As the computer proliferated, interfaces or adapters we are inverted that translated one machines code into a from that other could understand altering a variety of computers to be hooked together in a network.  But these interfaces were expensive both in agreegate because a substantial number of them needed to establish a large network, and singly, because each type of computer needed an interface of its own.  As a result there was little opportunity to spread the cost of developing give interfaces by selling many copies of it.  Netwo...