Nvi is an implementation of the ex/vi text editor originally distributed as part of the Fourth Berkeley Software Distribution (4BSD), by the University of California, Berkeley. The source code to nvi is freely available, and nvi may be freely redistributed.
Features:
Nvi supports all the historic ex/vi features except for open mode and the lisp edit option (e.g., it has a fully implemented underlying ex mode). It has a number of additional features as well:
8-bit clean data, lines and files limited by available memory
Multiple edit buffers
Colon command-line editing and path name completion
Tag stacks (including support for Cscope databases)
Extended Regular Expressions
Infinite undo
Horizontal scrolling
Message catalogs (Dutch, English, French, German, Russian, Spanish, Swedish)
Preliminary support for Perl and Tcl/Tk scripting languages
Nvi is maintained by Sven Verdoolaege and Keith Bostic.