Early text editors were line oriented and typically were used from dumb printing terminals. A typical editor that operates in this mode is Ed . The editor is powerful and efficient, using a very small amount of computer resources, and worked well with the display equipment of the time. vi offers the user a visual alternative with a significantly expanded command set compared with ed.
vi as we know it today started as the line editor ex . In fact ex is seen as a special editing mode of vi, although actually the converse is true. The visual component of ex can be initiated from the command line by using the vi command, or from within ex.
The ex/vi editor was developed at the University of California at Berkeley by William Joy . It was originally supplied as an unsupported utility until its official inclusion in the release of AT&T System 5 Unix. It has steadily become more popular, even with the challenges of more modern full screen editors.
Due to the popularity of vi there exists many clone variants and versions can be found for most operation systems. It is not the intention of this chapter to include all the commands available under vi or its variants. Many clones have expanded and changed the original behaviour of vi. Most clones do not support all the original commands of vi.
If you have a good working knowledge of ed then vi offers a smaller learning curve to master. Even if you have no intention of using vi as your regular editor, a basic knowledge of vi can only be an asset.