The vi Editor

• It is the standard editor in all UNIX-related systems
• It requires little space
• It does not require X Windows or any GUI

• man vi
• man ex

• full-screen editor
• two modes of operation: Command and Insert
• Use of one-letter commands
• Flexible search-and-replace facility with pattern matching
• but cryptic
• User-defined editing features using macros

$ vi filename

• If filename exists, vi creates a copy of it and puts the copy into a buffer file in the current directory (typically named .yourfilename.swp).
• If filename doesn't exist, vi opens an empty buffer in the same directory and gives the file the name specified in your vi command.

Exercise: create a new file

• start at your home directory

$ cd
$ vi testfile

• Notice at the bottom of the screen, the editor is telling you it is a "New File".
• Exit vi without making any changes, type

:q

• Since you didn't add any lines to the file, it was not created by vi.
• Lets create a practice file by copying the fstab file to your home directory

$ cp /etc/fstab .
$ vi fstab

• vi gives you the file name in double quotes at the bottom of the page,
• vi also displays the number of lines and number of characters in the file.

  The many way of exiting vi

  :q	quits vi without saving file.
  :wq	writes changes and quits.
  :q!	quits without writing changes.
  :x	another way to write changes and quit.
  <Shift>zz	writes changes and quits
  :wq!	allows you to write changes and quit when you own the file but don't have write permissions.

Getting around a file that exists in vi

Command Mode

Once you type the command vi  filename you leave the shell and move into vi's Command mode.

From the command mode you can:

• move around
• delete text, delete lines
• search forward using the slash (/)
• search backward using the question mark (?)

Moving the Cursor

• use arrow keys
• use j (down),  h (left), k (up), l (right)
• $ - takes you to the end of the current line
• ^ - takes you to the beginning of the current line

• Typing the forward slash '/' automatically puts you in text search forward mode.

Exercise: moving around the fstab file in our home directories

• Once inside vi, find the string "swap" by typing a forward slash and the word swap

$ vi fstab

• to continue searching in the same direction for the string, type n
• to search in the opposite direction, type N
• Typing the question mark '?' automatically puts you in text search backward mode.

?swap

• Delete two line below the line with the string swap in it
• Position your cursor below the line swap device
• Type 2dd
  • this deletes the current line and the line beneath it
• Save your changes and exit vi by typing :wq

General movement within the file

Moving cursor to top of file	1G
Moving cursor to bottom of file	G
moving to line number 7	7G
Finding out how many lines are in the file and the file name	<Control-g>

Deleting text in Command mode: lines, words, or characters

dd	remove a whole line
u	undo the last change
U	Restore the entire line (if the cursor has not left the line)
2dd	delete the current line and the one below it
D	delete the remainder of the line after the cursor
yy	copy one line
2yy	copy two lines
P	paste the copied or deleted line(s) above the line with the cursor
p	paste the copied or deleted line(s) below the line with the cursor
dG	deletes to the end of the file after the cursor
dw	delete current word - place cursor on first letter
3dw	delete 3 words
x	delete individual characters
d$	delete to the end of the line
dG	delete to the end of the file

Insert Mode (also known as append or text mode)

• The mode you are in when inserting (i) or appending (a) text
• Also for opening lines above (O) or below (o) the current location
• You leave command mode to add text to a file.

Single letter commands for inserting text:

i	inserts to the left of cursor
I	inserts text at beginning of the line where cursor sits
a	appends to the right of cursor
A	adds text beginning at end of the line where cursor sits
O	opens a line above the line where cursor sits
o	opens a line below the line where cursor sits

Exercise: practice using these single letter commands in insert mode

• First, positin the cursor at the point in a new or existing file where you want to begin inserting text.

  $ vi fstab

• move cursor to end of the first line, type $
• then type a - this will append text to the right of your cursor
• press <return> and being typing your new line (anything you want)
• Press the Escape to exit insert mode
  

  <Esc>

• now you can move about the file using the arrow keys
• save your changes and exit

  :wq

• To instruct vi to get you out of Insert mode and back to Command mode press <Esc>.
• If you press <Esc> a second time vi will send a beep sound to the terminal.

$ vi fstab

• move cursor to middle of the first line
• type i - this inserts text to the left of the cursor begin typing text
• press <Esc> to go back to Command mode
  

<Esc>

now you can move about with the arrow keys

Exit vi without saving changes

:q!

Saving as you go

• It is a good practice to save your work every so often when inside vi
• If you want to save your work without exiting, press <Esc> to reenter Command mode, then type the following:

:w

• make sure you are in Command mode (press <Esc>)
• move cursor to any location on a line
• type the open line command, o (lowercase o),
• this opens a line below the cursor
  • begin typing text
• press escape to go back to Command mode

<Esc>

• move to another location in the file
• type O (uppercase O), this opens a line above the cursor
• begin typing
• then save your changes and exit vi
  
  <Esc>
  :wq

• i   inserts to the left
• I inserts text at beginning of the line
• a  appends to the right
• A adds text beginning at end of the line
• O opens a line above
• o  opens a line below

• x   deletes a character
• dw deletes a word
• dd  deletes a line
• D   deletes the remainder of a line

Moving Text: using yank and put

Exercise: create a new file

$ cd
$ vi jack

• Type a, to enter append mode and being typing.

All work and no play makes Jack a dull boy.

• Press <Esc> to enter Command mode
• Type yy, to yank the one line of text you just created
• Type p, to put the text below the cursor line.
• Now you have:

All work and no play makes Jack a dull boy.
All work and no play makes Jack a dull boy.

• Add a 3rd line by typing o after positioning the cursor on bottom line and begin typing:

no play

• Press <Esc> to enter Command mode
• Move the cursor to the top line and yank two lines by typing 2yy.
• Move the cursor to the third line (no play) and type p for put
• Your new file should look like this:

All work and no play makes Jack a dull boy.
All work and no play makes Jack a dull boy.
no play
All work and no play makes Jack a dull boy.
All work and no play makes Jack a dull boy.

• Move the cursor to the third line again (no play) and type yy then P.
• This will put the yanked line above the line where you placed the cursor.
  • The yanked line is still in the vi buffer
• Use the dd command to delete a line and then use the P or p command to put it somewhere else.
  • Deleting a line put that line in the buffer
• You can also experiment with deleting and putting several lines.
• Save you file
• Jack would be proud!

  :wq

Executing Linux/UNIX Commands in vi

• Lets say you are inside vi and need to run a command but don't want to exit vi.
• The exclamation point (!) used in Command mode will create a shell for you to run a command.

$ cp /etc/passwd .
$ vi passwd

• To list the contents of the current directory from inside vi:

:!ls

• You can also insert the output of a command into your file.

G
o
<Esc>
!!date

• Type !!or :.! followed by the command to insert the output of the command in your text.
• If you have a number of commands you want to run but you don't want to exit vi you can create a shell by typing

<Esc>
:!sh

• When you are done, exit the shell typing <Ctrl> d or exit
• This will take you back to the file you were editing.
• You can also read the contents of another file into the file you  are currently editing.

<Esc>
:r jack
:wq

Options for Changing How vi Operates (more advanced)

• The default appearance and behavior characteristics of vi are set in the .exrc file in your home directory.

$ cat /home/pattyo/.exrc
set ts=4

A few vi Customizing Options (do not use the ":" inside the .exrc file)

:set all	display all settings
:set nu	turn on line numbering
:set nonu	turn off line numbering
:set list	display nonprintable characters
:set nolist	hide nonprintable characters
:set ts=4	tab set to four character jumps
:set ic	ignore case sensitivity
:set noic	set case sensitivity
:set wrapmargin=15	set automatic word wrap to 15 spaced before the right margin

• Turn on line numbering:

$ vi jack
:set nu
:set ic

• search for the string all (lower-case)

/all
:set noic

• search again for the string all (lower-case)

/all
:q

Advanced Concepts

Global Changes Substitution

• Change all occurances of the string dull to fun in our test file jack.

  $ vi jack
  :%s/dull/fun/g

Two other examples for making global substitutions

• From the current cursor location to the end of the file substitute:

  :.,$s/Jack/Jill/g

• From the beginning of the file to the end of the file substitute:

:1,$s/Jack/Jill/g

Deletion

• To delete all lines beginning with Jill

:g/^Jill/d

• Get rid of blank lines:

:g/^$/d

Sorting

• To sort the first column starting from the line where the cursor is to the first blank line    

  !}sort

• or

  :.,$!sort

• 
  
• To sort the second column starting from the line where the cursor is to the first blank line
  

!}sort +1

• "a is the name of the buffer
• you could have a buffer named "b as well
• If you modify the file jack, you must save it before it will allow you to edit the other file
• Here we are yanking 5 lines from jack and putting it into the file newjack.

$ vi /tmp/jack
"a5yy
:vi newjack
"ap