.TI EMACS
Introduction to the GNU Emacs Text Editor

.I Emacs
is a general-purpose, full-screen text editor that Academic
Computing Services provides with neither consulting
nor bug-fixing support.
The 
.I emacs
command resides in the directory
.I /usr/xtra ,
so you must either include it in your search path (type
.E "help searchpath"
for more information) or invoke it with its full name,
.E /usr/xtra/emacs .
We chose the GNU version \*- GNU stands for Gnu's Not Unix,
the name of a Unix-compatible software system intended
for free distribution \*- because it appears to be the most
popular and best-documented, not to mention cheapest,
of the various versions available.
.SH Key Features and Cautions
Here are some important factors to consider when using
.I emacs .
First of all, when there are system crashes, terminal disconnections,
or other problems that cause an editing session to be aborted,
.I emacs ,
like
.I vi ,
does its best to save your editor buffers before giving up, but unlike
.I vi ,
you have no recourse if you lose the results of your editing session.
In such a case
.I
you will not be eligible for any refund
.R
nor can you be assured that the problem will be fixed.
Second,
.I emacs
is perhaps the most powerful editor in existence, but it is also complex
and slow, especially on starting up (although it has screen updating
and typeahead facilities that make it seem faster than
.I vi
on a slow terminal).
On the other hand, it has an extensive built-in help mechanism
and a style that some people say is more natural than
.I vi 's.
The manual for this version of 
.I emacs
is currently available from the ACS Library in 218 Evans Hall.
.SH Other Advantages
.I Emacs
can easily be customized and extended with your own commands,
it can display two or more files at once (in different
regions of the screen called windows), and can do horizontal scrolling.
In support of text processing it can do automatic filling of text,
detection and correction of spelling mistakes, and textual transposition.
In support of program development it accomodates indentation and
comment styles for different programming languages, tag tables, and
Lisp expression evaluation.
Miscellaneous extra features include mechanisms for editing pictures,
editing directories, and handling mail.
One of the most unusual advantages of this version of
.I emacs ,
the GNU version, is that it is probably the most celebrated
program in the GNU free-software movement, which holds that good
programs should be shared without cost among people who want to use them.
See the manual section entitled ``The GNU Manifesto'' for more details.
.SH Local Differences
This version contains support for X Windows, a general-purpose
window package running on Micro-Vax and Sun workstations.
We will try to keep current with latest releases of
.I emacs
running on the campus, but once again, we cannot promise to
respond to specific new releases or bug reports.
.SH Getting Started
There are a few points to keep in mind when you first begin to use
.I emacs .
First, your TERM environment variable setting must be consistent
with your terminal or terminal emulator (just as for
.I vi ).
Second, the terminal or terminal emulator must be set up to send
full 8-bit bytes.
In a regular login session full 8-bit transmission can be enabled
by setting NO PARITY before entering
.I emacs ;
in an
.I rlogin
session you have to have invoked
.I rlogin
with the
.E \-8
option.
If the terminal type is wrong or 8-bit transmission is not set
(for example, if your terminal or terminal emulator is set up
for IBM CMS connections), you may get parity error messages
or garbage on the screen.

Another less crucial point is to turn off flow-control (xon/xoff)
in your terminal or terminal emulator, that is, to set it so
that it does not transmit Control-S and Control-Q characters
during your login session.
A symptom of this problem is the spontaneous occurrence of
the message ``I-search'' at the bottom of the screen.

To start up the editor, type
.E emacs ,
and to get out of it type the two-character sequence
.E "Control-X Control-C" .
Although the help mechanism is very powerful, we recommend
reading the first few chapters of the manual before starting up
.I emacs .
If you want to go ahead anyway, you may find it hard to get rid
rid of the help text displayed on your screen
when you have finished reading it:  use the two-character sequence
.E "Control-X 1"
(one) to restore your display to normal.
To get a tutorial type the sequence
.E "Control-H t" ;
if you select it
.I emacs
simply switches your editing session to a copy of a file which
is the tutorial; perhaps the easiest way to get out of the tutorial
is to type the sequence
.E "Control-X Control-C" .
There is also a very informative ``info'' facility; type
.E "ESC info"
to get into it.

After using the editor you may notice some new files in your
directory having the same name as the one you were editing but with
a `~' appended or a `#' prepended to the name.
These are special backup and auto-save files, respectively,
and are no cause for concern unless you want to save space,
in which case it is safe to remove them.


jak