The operations that you perform in vi fall into two general categories command mode operations,which consist of key sequences that are commands to the editor to take certain actions, and insert mode operations,which allow you to input text.The general organization of the vi text editor and how to switch modes. To change from the command mode ,which you are in when you first enter the editor,to the insert mode,type a valid comand,such as ,to append text at the end of current line,Certain commands that are prefixed with the :,/,?,or:! Characters, are echoed or shown to you on the last line on the screen and must be terminated by press ,To change from Insert Mode to Command Mode,press the key,The keystroke commands that you execute in vi are case-sensitive-for example,uppercase appends new text after the last character at the end of current line,whereas lowercase appends new text after the character the cursor is on. I,i Insert A ,a Appent O,o Open R,r Replace C,c Change