We believe that one or more of the following statements are adequate descriptions of Viper:

Viper Is a Package for Emacs Rebels;
it is a VI Plan for Emacs Rescue
and/or a venomous VI PERil.

Technically speaking, Viper is a Vi emulation package for Emacs. It implements all Vi and Ex commands, occasionally improving on them and adding many new features. It gives the user the best of both worlds: Vi keystrokes for editing combined with the power of the Emacs environment.

Viper emulates Vi at several levels, from the one that closely follows Vi conventions to the one that departs from many of them. It has many customizable options, which can be used to tailor Viper to the work habits of various users. This manual describes Viper, concentrating on the differences from Vi and new features of Viper.

Viper, formerly known as VIP-19, was written by Michael Kifer. It is based on VIP version 3.5 by Masahiko Sato and VIP version 4.4 by Aamod Sane. About 15% of the code still comes from those older packages.

Viper is intended to be usable without reading this manual; the defaults are set to make Viper as close to Vi as possible. At startup, Viper will try to set the most appropriate default environment for you, based on your familiarity with Emacs. It will also tell you the basic GNU Emacs window management commands to help you start immediately.

Although this manual explains how to customize Viper, some basic familiarity with Emacs Lisp is a plus.

It is recommended that you read the Overview node. The other nodes may be visited as needed.

Comments and bug reports are welcome. is the current address for Viper bug reports. Please use the Ex command :submitReport for this purpose.

Copyright © 1995–1997, 2001–2015 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual”, and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License”.

(a) The FSF’s Back-Cover Text is: “You have the freedom to copy and modify this GNU manual.”

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