Vi

Basics

• Modes:

i                   insert
Crtl + c or Esc     exit insert mode
ZZ or :x or :wr     save & exit

• EX Commands:

set number 		Displays line numbers
set nonumber 		Removes line numbers
set autoindent  	Automatic indentation in insert mode
set noautoindent	Removes the automatic indentation feature in insert mode
se tabstop=3 		Sets the number of spaces by which the tab indents during editing
syntax on 		Turns on highlighting of syntax
syntax off 		Turns off highlighting of syntax
set shiftwidth=4	The size of the indent, measured in spaces

• The .vimrc file

The EX commands (those that you key in after typing : in the Vi editor), which you want to execute whenever you start the Vi editor, can be saved in the .vimrc file in your home directory.

Intermediate

• Abbreviations can be set, which Vi will expand into full text whenever they are typed in edit mode

:ab  abbr   full text
:ab aman Amandeep Singh

The abbreviation can be disabled by:

:unab abbr
:unab aman

• Encryption in Vi

To encrypt any file in the Vi editor, type the following in command mode and press the Enter key,then Enter a password twice.:

:X 

To decrypt the encrypted file, open the file and type below command and hit the Enter key twice; then save and exit the Vi editor by typing :wq, the file will be saved in the decrypted format:

:X

• Inserting the contents of an existing file

: r  filename

• Opening Vi directly at a particular line

vim filename +5

• Opening Vi at the end of the file

vim + filename

• Writing the buffer to a new file

:w newname

You can now quit the original file by typing :q.

• Indenting the source code

gg=G

Where gg indicates the beginning of the file, = is for indenting and G indicates the end of the file.

• Repeating the last change

. (period)  key to repeat the last change. 

• Undoing and redoing

u           undo the last change.
Ctrl-R      repeat a change that has been undone.

• Jumping to matching braces

%           can jump to curly brace or square bracket

• Preventing auto-indent

:set pastetoggle=<F2>

You can then press <F2> in the insert mode when you are ready to paste. After pasting, you can press <F2> again to go to the auto-indent mode.

Advanced

• Going to any line

:50

• In the command mode to get the same result:

50G

Typing just G in the command mode takes the cursor to the last line of the file and typing 1G takes the cursor to the beginning of the file.

• Incrementing or decrementing a number

Ctrl-a
Ctrl-x

• Changing the case of letters

~         To toggle the case of the character below which the cursor is positioned
gUU       To change the case of the current line to upper case
guu       To change the case of the current line to lower case
g~~       To toggle the case of the current line
g~$       To toggle the case of all characters from the cursor position to the end of the line

• Sorting within Vi

:sort

• To sort lines and remove duplicate lines

:sort u

Executing a filter command

1. ‘!’ symbol is used within the command line of Vi editor to execute an external program.
2. The line number 1 and the $ symbol in the above command can be replaced with any portion of the file with the numbers of the starting line and ending line of the particular portion.

• To sort the file from the first line to the last line

:1,$!sort

• The -u option with sort will keep only the unique lines and remove the duplicate lines.

:1,$!sort -u

• To sort the lines starting from the contents of line number 5 to 15, give the following command:

:5,15! Sort

Using tr within Vi

• The following command will convert all the letters in the line numbers 10 to 20 to upper case:

:10,20 ! tr a-z A-Z

• Writing a portion of file, lines from 20 to 50 to a new file named newfile.txt:

:20,50 w > newfile.txt

Inserting the output of a command executed within the Vi editor

• Most users are familiar with the method to execute a shell command within the Vi editor.

:! ls

• Less known is the fact that you can insert the output of the command given within the Vi editor by placing a ‘.’ (period) before the exclamation mark.

:.! date
:r! date

• Cursor movements

H      The cursor is positioned at the first line of the screen
M      The cursor is positioned at the middle line of the screen
L      The cursor is positioned at the last line of the screen

• Scrolling through a file

Ctrl-f     Scroll down by one screen
Ctrl-b     Scroll up by one screen
Ctrl-u     Scroll up by half a screen
Ctlr-d     Scroll down by half a screen
zz         Scroll the screen so that the current line appears at the middle of the screen, very useful for viewing the block of code associated with the current line.

• Editing a file opened without sudo

Let’s assume that you are editing a file which requires root access, instead of saving the file by taking many steps, you can save it straight away by using a combination of the tee and sudo commands:

:w !sudo tee %1

• Powerful delete commands

di(      Deletes all characters within the parentheses
di”      Deletes all characters within the quotes

• Recovering a file, after a crash, from the swap file of the file being edited:

$vi -r filename