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Basic vi Commands



<br>Basic vi Commands<br>



Basic vi Commands








What is vi?



The default editor that comes with the
UNIX operating system is called vi (visual editor).
[Alternate editors for UNIX environments include pico
and emacs, a product of GNU.]


The UNIX vi editor is a full screen editor and has two modes of
operation:

  1. Command mode commands
    which cause action to be taken on the file, and
  2. Insert mode in which entered text is inserted into the file.

In the command mode, every character typed is a command that does
something to the text file being edited; a character typed in the
command mode may even cause the vi editor to enter the
insert mode.
In the insert mode, every character typed is added to the text
in the file; pressing the (Escape) key
turns off the Insert mode.


While there are a number of vi commands, just a handful
of these is usually sufficient for beginning vi users.
To assist such users, this Web page
contains a sampling of basic vi commands.
The most basic and useful commands are marked with an asterisk
(* or star) in the tables below.
With practice, these commands should become automatic.


NOTE: Both UNIX and vi are case-sensitive.
Be sure not to use a capital letter in place of a lowercase
letter; the results will not be what you expect.



To Get Into and Out Of vi


To Start vi




To use vi on a file, type in vi filename. If
the file named filename exists, then the first page (or screen)
of the file will be displayed; if the file does not exist, then an
empty file and screen are created into which you may enter text.






*
vi filename
edit filename starting at line 1
 
vi -r filename
recover filename that was being
edited when system crashed




To Exit vi




Usually the new or modified file is saved when you
leave vi. However, it is also possible to quit
vi without saving the file.


Note: The cursor moves to bottom of screen whenever a
colon (:) is typed. This type of command is completed by
hitting the (or ) key.









*
:x
quit vi, writing out modified file
to file named in original invocation

 
:wq
quit vi, writing out modified file
to file named in original invocation

 
:q
quit (or exit) vi
*
:q!
quit vi even though latest changes
have not been saved for this vi call





Moving the Cursor




Unlike many of the PC and MacIntosh editors, the mouse does not
move the cursor
within the vi editor screen (or window).
You must use the
the key commands listed below. On some UNIX platforms, the arrow keys
may be used as well; however, since vi was designed with
the Qwerty keyboard (containing no arrow keys) in mind, the arrow
keys sometimes produce strange effects in vi and should
be avoided.


If you go back and forth between a PC environment and a UNIX
environment, you may find that this dissimilarity in methods for
cursor movement is the most frustrating difference between the two.


In the table below, the symbol ^ before a letter means
that the key should be held down while the
letter key is pressed.















*
j or

  [or down-arrow]
move cursor down one line
*
k [or up-arrow]
move cursor up one line
*
h or

  [or left-arrow]
move cursor left one character
*
l or

  [or right-arrow]
move cursor right one character
*
0 (zero)
move cursor to start of current line
(the one with the cursor)

*
$
move cursor to end of current line
 
w
move cursor to beginning of next word
 
b
move cursor back to beginning of preceding word
 
:0 or 1G
move cursor to first line in file
 
:n or nG
move cursor to line n
 
:$ or G
move cursor to last line in file




Screen Manipulation




The following commands allow
the vi editor screen (or window) to
move up or down several lines and to be refreshed.










 
^f
move forward one screen
 
^b
move backward one screen
 
^d
move down (forward) one half screen
 
^u
move up (back) one half screen
 
^l
redraws the screen
 
^r
redraws the screen, removing deleted lines




Adding, Changing, and Deleting Text




Unlike PC editors, you cannot replace or delete text by highlighting it with
the mouse. Instead use the commands in the following tables.


Perhaps the most important command is the one that allows you
to back up and undo your last action. Unfortunately, this
command acts like a toggle, undoing and redoing your most recent
action. You cannot go back more than one step.





*
u
UNDO WHATEVER YOU JUST DID; a simple toggle




The main purpose of an editor is to create, add, or modify text
for a file.



Inserting or Adding Text




The following commands allow you to insert and add text.
Each of these commands puts the vi editor into insert mode;
thus, the key must be pressed to terminate the
entry of text and to put the vi editor back into command mode.











*
i
insert text before cursor, until hit
 
I
insert text at beginning of current line,
until hit

*
a
append text after cursor, until hit
 
A
append text to end of current line,
until hit

*
o
open and put text in a new line below current line,
until hit

*
O
open and put text in a new line above current line,
until hit




Changing Text




The following commands allow you to modify text.












*
r
replace single character under cursor
(no needed)

 
R
replace characters, starting with current cursor position,
until hit

 
cw
change the current word with new text,

starting with the
character under cursor, until hit

 
cNw
change N words beginning with character under cursor,
until hit;

  e.g., c5w changes 5 words

 
C
change (replace) the characters in the current line,
until hit

 
cc
change (replace) the entire current line,
stopping when is hit

 
Ncc or cNc
change (replace) the next N lines,
starting with the current line,

stopping when is hit




Deleting Text




The following commands allow you to delete text.












*
x
delete single character under cursor
 
Nx
delete N characters, starting with character under cursor
 
dw
delete the single word beginning with character under cursor
 
dNw
delete N words beginning with character under cursor;

  e.g., d5w deletes 5 words

 
D
delete the remainder of the line,
starting with current cursor position

*
dd
delete entire current line
 
Ndd or dNd
delete N lines, beginning with the current line;

  e.g., 5dd deletes 5 lines




Cutting and Pasting Text




The following commands allow you to copy and paste text.








 
yy
copy (yank, cut) the current line into the buffer
 
Nyy or yNy
copy (yank, cut) the next N lines, including the current line,
into the buffer

 
p
put (paste) the line(s) in the buffer into the
text after the current line





Other Commands



Searching Text




A common occurrence in text editing is to replace one word or
phase by another. To locate instances of particular sets of characters
(or strings), use the following commands.










 
/string
search forward for occurrence of string in text
 
?string
search backward for occurrence of string in text
 
n
move to next occurrence of search string
 
N
move to next occurrence of search string in opposite
direction




Determining Line Numbers




Being able to determine the line number of the current line
or the total number of lines in the file being edited is sometimes
useful.








 
:.=
returns line number of current line at bottom of screen
 
:=
returns the total number of lines at bottom of screen
 
^g
provides the current line number, along with the total
number of lines,

in the file at the bottom of the screen





Saving and Reading Files



These commands permit you to input and output files other
than the named file with which you are currently working.









 
:r filename
read file named filename and insert after
current line

(the line with cursor)

 
:w
write current contents to file named in original
vi call
 
:w newfile
write current contents to a new file named newfile
 
:12,35w smallfile
write the contents of the lines numbered 12 through 35
to a new file named smallfile
 
:w! prevfile
write current contents over a pre-existing file
named prevfile










ขอขอบคุณ : //www.cs.colostate.edu/helpdocs/vi.html


Create Date : 07 มิถุนายน 2551
Last Update : 7 มิถุนายน 2551 12:29:55 น. 0 comments
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