VI editor is the default file editor in most of the Linux/Nix machines. It is having great capabilities to edit a file with in few key strokes.

Lets start with some general information and then move on to some good things what vi editor can do for you while editing a file.
1. Vi stands for visual.
2. Vi have its variants like vim which stands for Vi IMproved, VimX11 for gui and winvi for MS windows.
3. Vi is the most popular editor and next most popular editor is gedit.
4. Do you know there is a book on VI editor from orally which is of 600+ pages.
5. Some other editors which will do the work of editing files are neno, pico, gedit, emacs, joe, nedit, ed etc.

Learning vi editor and remembering them is a very a easy task if you learn it in a systematic way.
a. Modes of VI
b. Navigational commands
c. Editing commands.
d. Search and Replace
e. Save and quiting a file.

a. Modes of VI :
Vi have two mode of operation.
1. Command mode
2. Inserting mode

Command mode :
Vi editor begins in command mode, where cursor movement(navigation in the file) and editing occur. To enter in to command mode from Inserting mode press esc button.

Inserting mode :
Used for entering text, this is similar to notepad in Windows. To enter in to inserting mode you can use any of the following.
i or I => present line
o => one line down the present line
O => one line above

Note : All comments will work in command mode only.

b. Navigational commands :
1. Character navigation k, h, l and j
h => To move one character left.
j => To move one line down.
k => To move one line up.
l => To move one character right.

How to use above commands in clever way?
Examples :
6j => to move 6 lines down from the present courser.
7k => to move 7 lines above from the present courser.

2. Word Navigation
w => word forward.
e =>word forward, but end of the word.
b => one word backward.

Examples :
32w => To move 32 words forward
6b => To move 6 words back.

3. Setting (nu) mbering to lines
:set nu
Removing of (nonu)mbering to lines
:set nonu

4. Moving paragraphs
move one paragraph up => {{
move one paragraph down => }}

5. Moving page up/down
For up => ctrl+b
For down => ctrl+f

6. Moving start/end of the file
Starting of the file(first line => [[
End of the file(last line) => ]]

7. Going to any line :
:lineno

Example :
If we want to go to 56 line then type
:56

c. Editing commands

8. Replace one letter
Replace one letter => r
Delete one letter => x

>9. Editing one word
Edit one word => cw
Delete one word => dw

10. Editing one line
Editing a line from courser to the end of that line => d$

11. Cutting
deleting(cutting) one line => dd

Examples :
2dd(deleting/cutting two lines)

12. Pasting
Pasting a line below the courser => p
Pasting a line above the courser => P

13. Coping
Copying one line => yy
Copying n lines => nyy

14. Special commands
joining lines => J
undoing things => u
repeating previous command => .

d. Search and replace

15. Search for a term /term

Example : If you want to search for suresh then press /suresh enter
/suresh
Moving to next occurrence, press “n” with out quotes moving to previous occurrence, press “N” with out quotes.

16. Searching and replacing a term(here separator is / )
:%s/searchterm/replaceterm/g
change default separator
:%s_/home/surya/grade_/home/testing/dest_g

To search and replace particular term from given line to other given line.
:%s294,304/sahana/xyz/g

e)Save and quiting a file
:w => save the file
:q => quit the file
:wq => save and quit
:w! => force save the file
:q! => force quit with out save
:wq => save and quit forcefully
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