Disk Management In Operating System

Image
 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...

Text Editor in Linux Operating System

 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. Last Line Mode 

At any time vi will be in one of these mode. 

The Command mode is one in which user is able to enter the commands, for e.g. To add text, to delete text. 

In Input or Insert mode the user can enter data or edit the data. 

The Last Line mode is one in which the user is able to enter special commands, which typically start with, : 

When VI is invoked, it comes up in command mode. For the user to be able to enter any text, the user must type a command that takes him into 'input' mode. The user can come back to 'command' mode by pressing the 'Escape' key. 

Starting 'VI' 

The 'vi' editor can invoked by typing the following command at the prompt. 

At command prompt, type the following, 

[user1 @linux-mac user1]$ vi 

Since the file name is not specified with 'vi' command ''Empty Buffer" is displayed at the end of the screen. 

An existing file can also be opened by specifying it's name with 'vi' command. 

The cursor is brought to a specifying the line number at the command promp  along with the file name. 

At the command promp type the following : 

[user1 @linux-mac user1]$ vi +5 candy 

The above command positions the cursor to the 5th line of the file called 'candy' 

Now type the following command :

[user1 @linux-mac user1]$vi +/fruit candy 

This command will take the user to the line in the file called 'candy' which contain the first occurrence of the string 'fruit'. 

Inserting Text 

To enter the data user have to switch to input mode by pressing character 'i'. 

List of Insertion Commands 

Command                   Purpose 

i : Invokes insert mode and inserts before character. 

I : Same as 'i' but insertion is at the beginning of the line. 

O : Open blank line before the current line. 

O : Same as 'o' but puts blank line after current line. 

a : Same as 'i' but appends after cursor. 

A : Same as 'a' but appends at the end of the line. 

J : Join the next line with the current line. 

Navigation 

The 'vi' editor gives the option of navigation without relying on the cursor keys. 

There are other commands to help in scrolling the screen. The character 'n' before the commands which are used in cursor control. 

List of cursor navigation commands 

Command                             Purpose 

k : same as "up" arrow key 

h : same as "left" arrow key 

l : same as "right" arrow key 

J : same as "down" arrow key   

w : moves forward by word 

'n' w : moves forward by 'n' numbers of word 

e : move to the last character of the world or that of next 

'n' e : move to the last character of n(th) next word. 

b : take the user back by word 

'n' b : take the user back by 'n' number of words 

0 or '^' : take the user to the beginning of the line 

$ : take the user to the end of the line 

'n' G : take the user to the n(th) line 

L : take the user to the last line 

Commands For Scrolling 

List of screen scrolling commands 

Command                     Purpose 

Ctrl - f : Scrolls a screen forward 

Ctrl - b : Scrolls a screen backward 

Ctrl - u : Scrolls half a screen backward 

Ctrl - d : Scrolls half a screen forward 

Ctrl - L : Refreshes the screen 

Undoing The Changes 

'vi' has the option for undoing the last action. The 'u' command removes the effect of last command. For e.g. If the block of text has been deleted by mistake, it can be undone by using the 'u' command. 

Copying and Moving Blocks of Text : 

To be able to select a block of text, we need to select the lines of text by taking the cursor to the first line of text block that we have to copy. We then need to first of all specify the no of lines followed by the command 'yy'. This copies the specified lines to temporary buffers. To be able to copy a block of text, we move a copy of the specified text to the temporary buffer. To be able to move a block of text, we move the specified text itself to temporary buffer. The paste command 'p' moves the text store in the temporary storage to the current cursor location. 

List of Copy Commands and Move Commands 

Command                       Purpose 

Yy : copy a line into temporary storage 

'n'yy : copy 'n' number of lines into temporary storage 

Dd : move a line in to temp storage 

'n'dd : move 'n' lines in to temp storage 

p : move the text from temp storage to the current position of the cursor. 

https://youtube.com/channel/UCLZqVRZUkuXIlST8BteqTig

This is the link of my YouTube please visit at this link and if you like it don't forget to like, share and subscribe the channel.

Comments

Post a Comment

Popular posts from this blog

Disk Management In Operating System

You must know about Adventure sports