9.1 The vi Editor
9.1.1 Introducing vi
The vi (visual display) editor is an interactive editor that is used to create and/or modify ASCII (American Code for Information Interchange) text files. It is a character-based editor that is an integral part of all UNIX operating systems. The vi editor uses a screen display, but you cannot use the mouse to position the cursor. All editing with the vi editor is done within a memory buffer. Changes can be written to the disk or discarded. The vi editor works only with text files and does not have any formatting capabilities.

For users learning to become system administrators, it is important to know how to use vi. It is sometimes the only full screen editor available to edit crucial system files. Examples of these include scripts and environment control files. Since it does not impart any special formatting characters, the vi editor can also be used to create programs for various programming languages. Skill in using vi is also needed if the windowing system is not available. The vi editor is a useful tool when working remotely on other UNIX workstations or servers. Administrators routinely remote login or telnet to another UNIX computer to perform maintenance and troubleshooting tasks using vi. The availability and operation of vi is consistent across all UNIX platforms and thus it is a tool that will always be available.