3.4. The vi Editor

Text editors are still used for many system administration tasks as well as for programming. In the world of Unix, vi stands out as an editor that offers comfortable editing functions and is more ergonomic than many editors with mouse support.

3.4.1. Operating Modes

[Note]Display of Keys

In the following, find several commands that you can enter in vi by just pressing keys. These appear in uppercase as on a keyboard. If you need to enter a key in uppercase, this is stated explicitly by showing a key combination including the Shift key.

Basically, vi makes use of three operating modes: insert mode, command mode, and extended mode. The keys have different functions depending on the mode. On start-up, vi is normally set to the command mode. The first thing to learn is how to switch between the modes:

Command Mode to Insert Mode

There are many possibilities, including A for append, I for insert, or O for a new line under the current line.

Insert Mode to Command Mode

Press Esc to exit the insert mode. vi cannot be terminated in insert mode, so it is important to get used to pressing Esc.

Command Mode to Extended Mode

The extended mode of vi can be activated by entering a colon (:). The extended or ex mode is similar to an independent line-oriented editor that can be used for various simple and more complex tasks.

Extended Mode to Command Mode

After executing a command in extended mode, the editor automatically returns to command mode. If you decide not to execute any command in extended mode, delete the colon with <—. The editor returns to command mode.

It is not possible to switch directly from insert mode to extended mode without first switching to command mode.

vi, like other editors, has its own procedure for terminating the program. You cannot terminate vi while in insert mode. First, exit insert mode by pressing Esc. Subsequently, you have two options:

  1. Exit without saving: To terminate the editor without saving the changes, enter : Q ! in command mode. The exclamation mark (!) causes vi to ignore any changes.

  2. Save and exit: There are several possibilities to save your changes and terminate the editor. In command mode, use Shift-Z Shift-Z. To exit the program saving all changes using the extended mode, enter : W Q. In extended mode, w stands for write and q for quit.

3.4.2. vi in Action

vi can be used as a normal editor. In insert mode, enter text and delete text with the <— and Del keys. Use the arrow keys to move the cursor.

However, these control keys often cause problems, because there are many terminal types that use special key codes. This is where the command mode comes into play. Press Esc to switch from insert mode to command mode. In command mode, move the cursor with H, J, K, and L. The keys have the following functions:

H

Move one character to the left

J

Move one line down

K

Move one line up

L

Move one character to the right

The commands in command mode allow diverse variations. To execute a command several times, simply enter the number of repetitions before entering the actual command. For example, enter 5 L to move the cursor five characters to the right.

A selection of important commands is shown in Table 3.1, “Simple Commands of the vi Editor” This list is far from complete. More complete lists are available in the documentation found in Section 3.4.3, “For More Information”

Table 3.1. Simple Commands of the vi Editor

Esc

Change to command mode

I

Change to insert mode (characters appear at the current cursor position)

A

Change to insert mode (characters are inserted after the current cursor position)

Shift-A

Change to insert mode (characters are added at the end of the line)

Shift-R

Change to replace mode (overwrite the old text)

R

Replace the character under the cursor

O

Change to insert mode (a new line is inserted after the current one)

Shift-O

Change to insert mode (a new line is inserted before the current one)

X

Delete the current character

D D

Delete the current line

D W

Delete up to the end of the current word

C W

Change to insert mode (the rest of the current word is overwritten by the next entries you make)

U

Undo the last command

Ctrl-R

Redo the change that was undone

Shift-J

Join the following line with the current one

.

Repeat the last command

3.4.3. For More Information

vi supports a wide range of commands. It enables the use of macros, shortcuts, named buffers, and many other useful features. A detailed description of the various options would exceed the scope of this manual. SUSE Linux comes with vim (vi improved), an improved version of vi. There are numerous information sources for this application:

[Important]The VIM License

vim is “charityware,” which means that the authors do not charge any money for the software but encourage you to support a nonprofit project with a monetary contribution. This project solicits help for poor children in Uganda. More information is available online at http://iccf-holland.org/index.html, http://www.vim.org/iccf/, and http://www.iccf.nl/.