- Control + g   -----> Check the number of lines.
- G         	-----> GO to the end of the file.
- cc		-----> Replace the entire line.
- Control + l	-----> Redraw the screen.
- D		-----> REplace the entire line starting at the cursor.
- J		-----> Joining 2 lines.
- :sh		-----> give several Unix commands in a row w/o returning to VI, when done press Control + d.
- :r !date	-----> read into the system's date and insert the info below the current cursor.
- :r !sort phone	-----> read into the "phone" file then sort it, then insert the contents of the file "phone" below the current cursor.
- :r file	-----> Append the contents of the file "file" below the current cursor. THis is how to do appending in VI.
- :set number	-----> Display line number in VI.
- :set nu	-----> Display line number in VI.
- :.#		-----> Display the current line number.
- :.,+10#	-----> DIsplay the current line number AND the next 9 lines with preceding line number (for a total of 10 lines).
- :=		-----> print the total number of line.
- :/pattern/=	-----> Print the line number of the first one that matches pattern.st
- :set nonumber	-----> DO not display line number.
- :set nonu	-----> DO not display line number.
- :set window=20	-----> set the number of lines shown in the screen's window.
- :set ic	-----> specify search pattern should ignore case.
- :set noic	-----> specify search to be case sensitive.
- The .exrc file controls your VI environment and it is in your home directory.
- :1,10!sort	-----> Sort from line 1 thru line 10.
- !)  then we will see at the bottom of the screen the "!" sign, typing
	tr '[a-z]' '[A-Z]'
will change all lower cases letters into upper cases letters.
- !10+ then we will see the "!" sign at the bottom of the screen. by typing
	tr '[a-z]' '[A-Z]'
will change all lower case letters into upper case letters from the current line up to the next 9 lines.(for a total of 10 lines)
- :.,$d		-----> Delete from current line to the end of file.
- %d		-----> Delete all lines in the file.
- :.,.+20d	-----> Delete from current line thru the next 20 lines. 
- :/pattern/d	-----> Delete the next line that conatins "pattern"
- :/pattern1/, /pattern2/d	-----> Delete from the firrst line containing pattern1 thru the first line containing pattern2.
- :g/pattern/p	-----> Finds and displays all lines in the file containing pattern.
- :1,20w newfile	-----> will save line 1 to line 10 to the file "newfile".

- :20,$w newfile	-----> will save the contents from line 20 to the end of the file to the file "newfile".
- :1,$s/old/new/g	-----> change ever occurence of "old" to "new" within the entire file.
- :%s/old/new/g	-----> change ever occurence of "old" to "new" within the entire file.
- :g/^$/d	-----> Delete ALL blank lines.
- :g/^[ tab]*$/d	-----> Delete ALL blank lines but with white spaces and tab(s) in that line (non-readable cahracters).