@comment  node-name,  next,  previous,  up
@node Entering, Windows and Menus, Concept Index, Top
@chapter Entering and Exiting Emacs
@cindex buffer
@cindex file
@cindex windows

While using Emacs you should be familiar with the following three terms:

@table @asis
@item Buffer
A @b{buffer} is a region of memory holding characters. It is the basic
editing unit; one buffer corresponds to one piece of text being
edited. You can have multiple buffers but you can edit only one buffer
at any one time. For more information, @xref{Buffers,,,xemacs,XEmacs User's
Manual}.

@item File
A @b{file} is a region of disk space holding characters. Emacs edits a file by 
reading it into a buffer, editing that buffer and writing out the buffer 
back to the file. To save your work permanently you have to write it to a file.
So after you load and work with a file, you have to save it back.

@item Windows
A @b{window} is a rectangular region in which a buffer is displayed. You can 
open multiple windows with multiple buffers and edit them by selecting the 
corresponding buffer. Initially, when you start emacs, it will automatically 
open up a window for you.
@end table

@comment  node-name,  next,  previous,  up
@menu
* Enter::                       Entering Emacs from the shell
* Frame::                      Basic information about the XEmacs Frame
* Exiting::                     Exiting Emacs
* Mode Line::                   Interpreting the mode line.
* Echo Area::                   Bottom of the frame where you interact
                                with Emacs.
@end menu

@node Enter, Frame, Entering, Entering
@section Entering Emacs
@cindex entering Emacs
@cindex entering XEmacs

To enter Emacs type @kbd{xemacs} and press the Return key at the
shell i.e. @kbd{xemacs @key{RET}}. 
This will bring up an emacs window with @samp{*scratch*} as the default
buffer because Emacs must always have a buffer to work on. Then choose 
the @b{Open...} option from the @b{File} menu on the menubar at the top 
of the frame. It will prompt you to enter a filename. After you enter
the filename, Emacs will read that file into the current buffer. You can
also type :
@example
@kbd{xemacs <filename> @key{RET}} 
@end example
directly which will bring up
an Emacs frame with the @dfn{filename} as the buffer. 
 

@comment 
@node Frame, Exiting, Enter, Entering
@section Emacs Frame
@cindex open another file

When you run XEmacs under X, a menu bar on top of the Emacs frame
provides access to pull-down menus of file, edit, and help-related
commands. The menus only provide convenient shortcuts, the options that
they provide are available via key commands. You can invoke those
commands from the keyboard also. For many of the options, their
corresponding key commands are displayed right besides them. The five
default menus on the menubar that you will see on the frame are
@b{File}, @b{Edit}, @b{Options}, @b{Buffers} and @b{Help}. @xref{XEmacs
Pull-down Menus,,,xemacs,XEmacs User's Manual}, for detailed information on
the functions provided by the pull-down menus.

  The Emacs frame has a rectangle shaped box at the extreme right and you can
drag it up or down to scroll the window accordingly. Clicking on the
arrows also serves the same purpose. 

  The last line in your window is @samp{the Mode line} which will give
you a description of what's going on in that particular
window. @xref{Mode Line}, for more
information. Below the mode line is the @samp{Echo area}. Emacs uses
this area to interact with the user. @xref{Echo Area}. 

  If you wish to open another file in a new window after you enter
XEmacs, select @b{Open in New Frame...} from the @b{File} menu, which
will prompt you for a filename and open a new window with that filename
as the current buffer. If you want to open a new file in the same
window, select @b{Open..} from the @b{File} menu. You need to enter
XEmacs only once, you can edit multiple files by opening several other
frames or by switching between buffers.


@comment new section
@node Exiting, Mode Line, Frame, Entering
@section Exiting Emacs
@cindex exiting
@cindex killing Emacs
@cindex suspending
@cindex shrinking XEmacs frame

There are two commands for exiting Emacs, one for @dfn{suspending} Emacs
and the other for @dfn{killing} Emacs. @dfn{Suspending} means stopping 
Emacs temporarily and returning control to the shell, allowing you to 
resume editing 
later in the same Emacs job, with the same files, same kill ring, same
undo history, and so on.  This is the usual way to exit.  @dfn{Killing}
Emacs means destroying the Emacs job.  You can run Emacs again later,
but you will get a fresh Emacs; there is no way to resume the same
editing session after it has been killed. 

@kindex C-z
@findex suspend-emacs
@kindex C-x C-c
@findex save-buffers-kill-emacs
 
@table @kbd
@item C-z
Suspend Emacs (@code{suspend-emacs}).  If used under the X window system,
this command will shrink the X window containing the Emacs frame to an 
icon. Clicking on the icon will resume that Emacs process
again. @xref{Exiting Emacs,,,xemacs,XEmacs User's Manual}. 

@item C-x C-c
Kill Emacs (@code{save-buffers-kill-emacs}). You can also select 
@b{Exit Emacs} option from the @b{File} menu to kill that Emacs
process. If you haven't saved the file, Emacs will ask you if you wish
to save the file before killing that process. 
@end table



@comment node-name,  next,  previous,  up
@node Mode Line, Echo Area, Exiting, Entering
@section The Mode Line
@cindex mode line
@cindex top level

  When you enter XEmacs, each text window's last line is a @dfn{mode
line} which describes what is going on in that window. Normally, the
mode line looks like :

@example
@cartouche
--@var{ch}-XEmacs: @var{buf}     (@var{major} @var{minor})----@var{pos}------
@end cartouche
@end example

@noindent
This gives information about the buffer being displayed in the window: the
buffer's name, what major and minor modes are in use, whether the buffer's
text has been changed, and how far down the buffer you are currently
looking.

  The @var{ch} contains :
@table @samp
@item **
if the text in the buffer has been edited

@item --
if the text in the buffer has not been edited

@item %%
if the buffer is a read-only-buffer i.e. it cannot be edited
@end table

  @var{buf} is the name of the window's chosen @dfn{buffer}. If you are
editing a file (which is the selected buffer), the file name appears
in @var{buf}.  @xref{Buffers,,,xemacs,XEmacs User's Manual}.

  @var{pos} contains :
@table @samp
@item All
if your entire file is visible on the screen.
@item Top
if you are looking at the beginning of the file.
@item Bot
if you are looking at the end of the file.
@item @var{nn}%
@var{nn} will be a number corresponding to the percentage of the file
above the top of the screen, for example @samp{52}, which means that 52%
of the file is above the top of the screen.
@end table

   @var{major} is the name of the @dfn{major mode} in effect in the
buffer.  At any time, each buffer is in one and only one major mode.
The available major modes include Fundamental mode (the least
specialized), Text mode, Lisp mode, and C mode.  @xref{Major
Modes,,,xemacs,XEmacs User's Manual}, for details on how the modes differ
and how you select one.

   @var{minor} is a list of some of the @dfn{minor modes} that are
turned on in the window's chosen buffer.  For example, @samp{Fill} means
that Auto Fill mode is on which means that lines are broken
automatically when they become too wide. @xref{Minor
Modes,,,xemacs,XEmacs User's Manual}, for more information on various
minor modes and how to enable them.

  You can also display time in the mode line. @xref{The Mode
Line,,,xemacs,XEmacs User's Manual}, for more information regarding the
mode line.


@comment  node-name,  next,  previous,  up
@node Echo Area,  , Mode Line, Entering
@section The Echo Area
@cindex echo area

  The line at the bottom of the frame (below the mode line) is the
@dfn{echo area}.  Emacs uses this area to communicate with you:

@itemize @bullet
@item
  The @dfn{echo area} will print out the characters that you type. For
example, if you choose the @b{Open...} option from the @b{File} menu you
might get the following in the echo area:

@example
Find file: /usr/lib/x11/
@end example

@noindent
Now you need to give a file name to open, for example if the file name
is @file{myfile}, you will type @file{myfile} after
@file{/usr/lib/x11/} and press the @key{Return} key. If you pause for
more than a second while typing, you will see the characters that you
type in the @dfn{echo area}. 
@item
  The @dfn{echo area} also prints error messages. For example, if you
misspell @samp{usr} and type @file{/urs/lib/x11/myfile} @key{RETURN} in
the above example you might get an error message. Since 
Emacs will not be able to find the @file{/urs} 
directory, the @dfn{echo area} will say:

@example
@error{} Opening directory: no such file or directory, /urs/lib/x11/myfile
@end example

@noindent
This error message will be accompanied by a beep. Some XEmacs commands
will print informative messages in the @dfn{echo area}. @xref{The Echo
Area,,,xemacs,XEmacs User's Manual}, for more information on the @dfn{echo
area}.
@end itemize