Vi - UNIX editor - Short Manual (print landscape) "When using vi, if you don't know where you are, press Esc key, to go to the command mode"
This manual is designed to familiarizes users with some of the commonly used vi commands. Please follow all the instructions. Perhaps the most important thing about this editor is to remember that vi has two modes; 1) Input mode : invoked by pressing I, and it is used when you want to type, and 2) Command mode : invoked by pressing Esc, and it is used to do other things, except typing, for instance; moving up-down, left-right, deleting characters, words, lines, saving, exiting, etc. 
Note: In this manual, the words following a % symbol and written in boldface, for eg. % vi, are to be typed out ( without the % symbol). The words written in regular font following the % symbol and boldfaced commands are to be substituted by filename names in your system .
Step (1) : Opening vi:
At the prompt type % vi and press Enter, a blank screen will appear. A blank vi page will open in the command mode.
Step (2) : Typing a text, saving it, and exiting vi
2-1) Type the following 4 lines of text exactly the way it is shown below. To start typing press i to enter the Input mode, and type the following text.
"Depends on the size of the machine, a UNIX mashine can support
from one to handred users. Each user can run different set of programs.
Since a UNIX machine can support several users at the same time, 
the cost of computer per usr is much les.
2-2) Lets save it in the file text1;To save what you have typed press : Esc to go to command mode, then type: :wq text1 and press Enter(don't forget the : before the w) you are back at the command prompt again, %
2-3) To open file text1 again type : % vi text1
2-4) To leave the file without making any change, press Esc, then type : :q! (don't forget the : and the !)
Step (3) : Editing a file, save the changes, and exit vi 
3-1) To open the file in vi, at the command prompt type :% vi text1
3-2) To find a word in the text, for instance mashine, type : :/mashine (don't forget the : and the /)
3-3) Moving on a letter and replacing it with another one : use arrow to move on the letter s in the word mashine, press r (replace) and press c.
3-4) To go to a particular line for instance line 2 type : :2 (don't forget : before 2)
3-5) Delete a character and type a new one in its place : move on the letter a in handred, press x to delete a, press I to switch to input mode, type u, press Esc to switch to the command mode.
3-6) Move to the end of the file : press Shift and G
3-7) Use arrow to move the cursor to the beginning of the word usr

Note: in the command mode, letters i, j, k, and i can be used for navigating up, down, left, and right.

3-8) To delete the word usr press dw (this will delete the word in front of cursor)
3-9) Press I and type the word user, then press Esc to switch to command mode
3-10) To append s after the word les, move to s and press a (append), and type the missing s, press Esc.
3-11) save the file and exit : :wq (remember the : before w)
Congratulations. You just finished the basics of what you need to know to work with vi editor. The following is a list of some more vi commands.
Vi Command Description
yy followed by p command  the yy command copies the current line and p command will paste it at as new line after the cursor
yyn Yank n lines (default is 1) starting from the current
p Put after the line where the line(s) you yanked right cursor is
$ End of line
End of the word to the right
o Open a line below the current line
O Open a line above the current line
x Delete the character
nx Delete the number of characters specified by n, starting with the current
u Undo the change
ddn Delete the current line
) End of sentence
( Beginning of sentence
} End of paragraph
{ Beginning of paragraph
0 Beginning of line
A Add text at the end of the line
J Move down
H Move Right
K Move Up
L Move Left