Command Overview

vi commands are 1-letter abbreviations. vi has many commands and you may not use all of them when you edit a file. There are often many ways to do the same thing in vi, especially because you can put them together.
You will be expected to learn many commands, but while you are working on your own you will remember and use the ones that work the best for you. The important skill to take away from this class is the ability to make any changes to a file using vi that you might need to do.
One of the best ways to learn the commands is to recite in your head what the command stands for as you use it. For instance, i stands for insert.
When working in vi, you will start out in command mode. This means that vi is waiting for you to give it a command.
The other mode is called edit mode. This means that the letters you type are inserted into the file you are editing. Pressing the escape key will put you back into command mode.
There are 3 kinds of commands in vi:
1. Navigation Commands - these commands move you around in the file by moving your cursor. In vi, it is important to know where your cursor is; you will not use a mouse or other pointing device to change it. Any changes you make will typically occur base on the current cursor position.
  An example of a navigation command is e (for end), which will move your cursor to the end of the current word.
2. Editing Commands - these commands make changes. Remember, though, that the file is not really changed until you save it.
  An example of an editing command is x (it "x's" out a character), which deletes the current character.
3. ex Commands - these are commands from an older editor that were incorporated into vi. You can recognize ex commands because they all start with a colon, your cursor drops to the bottom of the screen, you type in the command, then press enter. ex commands are typically longer than 1 character, but are some of the most powerful commands you can use in vi.
  An example of an ex command is :w (for write), which is one way to save your changes and remain in vi.
We will learn commands from all 3 categories.
There are 3 basic behaviors for a command:
1. Some commands will put you in edit mode, which means that the letters you type are entered into the file until you press the escape key.
  An example of a command of this type is s (for substitute), which replaces the current letter with everything you type until you press escape.
2. Some commands will immediately make the change or move the cursor and you will remain in command mode.
  An example of a command of this type is J (for join), which joins two lines together (the next one is joined with the current one.)
3. A few others will make a change that lets you enter a single character, then you are automatically put back in command mode.
  An example of a command of this type is r (for replace), which replaces the current letter with the next letter you type and then puts you right in command mode.

Explanation of Commands

Remember, vi commands are abbreviations. If you use the correct words, remembering the commands will be much easier. (You may have heard the term mnemonics, which means to use short-hand symbolic memory aids to remember things like commands. vi commands are an example of using mnemonics in computer science.)
Also, you can put commands together. In general, if it makes sense, it probably works.
When in doubt, give it a try and see! You can undo it if it is not what you want. (So, make a guess - what 1-letter command do you think is used for undo?)
As an example, w stands for word and will move the cursor to the next word (so what kind of command is it?). The command d stands for delete and is used to delete things. What do you think the command dw does? Guess the obvious and you will be correct.