A Short Description of vi  vi is a full-screen text editor
originally written to run under Unix, but it has been cloned and
imitated to run under MS-DOS, Windows, OS/2, Macintosh OS, Unix,
and several other operating systems as well. vi is unusual in
that it has two modes: an input mode in which text may be
inserted, appended, or overwritten, and a command mode in which
the user may issue searches and/or replacements of text, move
around the file being edited, delete and copy text, perform file
operations (read/write/save), and invoke external system
commands (such as the Unix commands sort, date, and fmt).  Up
and Running Fast, But Powerful Basic editing tasks with vi
(opening a file, moving around, inserting text, deleting text,
saving the file) can be learned in a few minutes, but mastering
this editor will take much longer since it is relatively
feature-rich and it can draw upon the full power of Unix,
including regular expressions, reading the output of external
commands, and allowing exernal commands to