Appendix 2: Text Editors

241

vi

One of the standard editors found on any UNIX system, vi, is a modal editor

that provides many useful features. This section is not spacious enough to do

justice to vi's many features, so only the basic commands needed to do simple

editing will be covered here. A few of the more useful commands include:

:viusage

Show a list of vi commands.

:exusage

Show the list of ex commands.

:q!

Unconditional exit back to the shell.

:wq

Write the file and quit.

i

Enter insert mode (characters can only be entered when

in input mode).

Return to command mode.

Modal refers to the way that vi operates in different modes. When first in 

voked, vi is in command input mode. The cursor can be moved around the

screen, but any other keys typed are expected to be commands. Some of those

commands, like the i command, switch the editor into text input mode. For

the insert command, the characters typed are inserted to the left of the cursor.

The escape key will return to command mode, either from text input mode or

to abort a command in the middle. If you type several characters that do not

create a command, no other command can be entered until these characters

are cleared. The escape key returns to command input mode and clears the

partial command.