Emacs, GNU-Emacs and XEmacs

Information Systems Department

This document describes the GNU Emacs and XEmacs editors as supported by ISD at UMIST. Both are installed and available for use on Cosmos, the UMIST general-purpose Solaris/Unix server; GNU Emacs is available in the PC Clusters on Windows NT, but is not supported.

Both editors are released under the GPL and are therefore available for free download, installation and use.

Document History

  1. First draught: 2001 July 2, Simon Hood.


While ISD has taken great care in the preparation of this document, it assumes no responsibility for errors or omissions, or for problems resulting from the use of the information contained therein.


Copyright © 2001, Information Systems Department, UMIST, Manchester, England.

1. Introduction

In short, Emacs is a text-editor --- in fact, Emacs is much more than that: its a lisp-based advanced, self-documenting, customisable, extensible editor.

There are two well-known versions of Emacs: GNU Emacs, written by members of the Free Software Foundation; and XEmacs, a derivative of GNU Emacs.

N.B. "XEmacs" is a misleading name: in Unix-speak, a prefix of "x" to the name of an application usually means the application is X-aware (i.e., works with the X-Window protocol). In fact both GNU Emacs and XEmacs are X-aware and in addition GNU Emacs will happily work within, for example, a VT100 terminal.

Emacs is available for all "major" operating systems, including Solaris, Irix, Linux, *BSD and Microsoft Windows.

2. Emacs at UMIST

Both GNU-Emacs and XEmacs are available on Cosmos, and are supported at Level 4. GNU-Emacs is also available on the public PC clusters, but is unsupported there.

2.1. GNU Emacs

To start GNU Emacs on Cosmos, simply type emacs at the command line. After a few moments GNU Emacs will start, assuming it has been found on your path. (The full path is /usr/local/bin/emacs, which should always work, irrespective of your path.)

GNU Emacs will start in one of two modes:

  1. If the DISPLAY environment variable is set GNU Emacs will attempt to start as an xclient, that is, launch a window on the display given by DISPLAY --- sometimes DISPLAY is set automatically when you login to Cosmos, otherwise you will need to use the setenv or export command depending upon which shell you are using.
  2. If DISPLAY is not set, GNU Emacs will open in a VT100 (like) mode.
(You may also need to give Cosmos "permission" to open a window on you local machine using xhost if your local machine is a Unix/Linux box; if you are using eXceed this should be done automatically.)

2.2. XEmacs

To start XEmacs on Cosmos, simply type xemacs at the command line. After a few moments GNU Emacs will start, assuming it has been found on your path. (The full path is /software/SUNWspro/bin/xemacs, which should always work, irrespective of your path.)

XEmacs can be run as an xclient, or in VT100 mode, exactly like GNU Emacs, above.

3. On-Line Tutorial

There an excellent on-line tutorial for emacs available at family.zawodny.com; the tutorial may be downloaded in several formats, including postscript for printing.

This tutorial is mirrored at the Linux Documentation Project site at MCC.

4. GNU Emacs

I quote:
An extensible, real-time display editor and computing environment. It offers true Lisp, smoothly integrated into the editor, for writing extensions and provides an interface to the X windows system.

...extraordinarily powerful text editor with additional features including content sensitive major modes, complete online documentation, highly extensible through Lisp, support for many languages and their scripts, and a large number of other extensions available either separately or with the GNU Emacs distribution. It runs on seven different operating systems regardless of machine.

All GNU documentation for all GNU software is available on-line in various formats. In particular all application manuals are available, including the complete (200 page) manual for Emacs v 20.3 (v20.4.1 is installed on Cosmos at the time of writing, but this is not substantially different).

5. XEmacs

I quote:
XEmacs is a highly customizable open-source text editor and application development system. It is protected under the GNU Public License and related to other versions of Emacs, in particular GNU Emacs. Its emphasis is on modern graphical user interface support and an open software development model, similar to Linux. XEmacs...runs on Windows 95 and NT, Linux and nearly every other version of Unix in existence. Support for XEmacs has been supplied by Sun Microsystems, ... and others...

6. Some History

There is some information at www.xemacs.org concerning the split between GNU Emacs and XEmacs. There is also information comparing the two.

7. Coffee

I often tell people whom I am introducing to Emacs that it will do everything bar make the coffee. This is no longer true: herewith I quote a news item from www.xemacs.org:

29 September 1999: The first public release of coffee.el allows RFC2324-compliant coffee devices (Hyper Text Coffee Pot Control Protocol, or HTCPCP) to be controlled from within XEmacs. Coffee-drinking XEmacs users everywhere rejoice as their favorite beverage is unified with their favorite editor.

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