@c This is part of the XEmacs manual.
@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995 Free Software Foundation, Inc.
@c See file xemacs.texi for copying conditions.
@node Entering Emacs, Exiting, Pull-down Menus, Top
@chapter Entering and Exiting Emacs
@cindex entering XEmacs
@cindex starting XEmacs

  The usual way to invoke XEmacs is to type @kbd{xemacs @key{RET}} at
the shell.  XEmacs clears the screen and then displays an initial
advisory message and copyright notice.  You can begin typing XEmacs
commands immediately afterward.

  Some operating systems insist on discarding all type-ahead when XEmacs
starts up; they give XEmacs no way to prevent this.  Therefore, it is
advisable to wait until XEmacs clears the screen before typing your first
editing command.

  If you run XEmacs from a shell window under the X Window System, run it
in the background with @samp{xemacs&}.  This way, XEmacs does not tie up
the shell window, so you can use that to run other shell commands while
XEmacs operates its own X windows.  You can begin typing XEmacs commands
as soon as you direct your keyboard input to the XEmacs frame.

@vindex initial-major-mode
  Before Emacs reads the first command, you have not had a chance to
give a command to specify a file to edit.  Since Emacs must always have
a current buffer for editing, it presents a buffer, by default, a buffer
named @samp{*scratch*}.  The buffer is in Lisp Interaction mode; you can
use it to type Lisp expressions and evaluate them, or you can ignore
that capability and simply doodle. (Which is where the name comes from;
a ``scratch pad'' is a set of paper for doodling on, something not
necessarily clear to all the English-speakers who read this.)

You can specify a different major mode for this buffer by setting the
variable @code{initial-major-mode} in your init file.  @xref{Init File}.

  It is possible to specify files to be visited, Lisp files to be
loaded, and functions to be called, by giving Emacs arguments in the
shell command line.  @xref{Command Switches}.  But we don't recommend
doing this.  The feature exists mainly for compatibility with other
editors.

  Many other editors are designed to be started afresh each time you
want to edit.  You edit one file and then exit the editor.  The next
time you want to edit either another file or the same one, you must run
the editor again.  With these editors, it makes sense to use a
command-line argument to say which file to edit.

  But starting a new Emacs each time you want to edit a different file
does not make sense.  For one thing, this would be annoyingly slow.  For
another, this would fail to take advantage of Emacs's ability to visit
more than one file in a single editing session.  And it would lose the
other accumulated context, such as registers, undo history, and the mark
ring.

  The recommended way to use XEmacs is to start it only once, just
after you log in, and do all your editing in the same Emacs session.
Each time you want to edit a different file, you visit it with the
existing Emacs, which eventually comes to have many files in it ready
for editing.  Usually you do not kill the Emacs until you are about to
log out.  @xref{Files}, for more information on visiting more than one
file.

@node Exiting, Command Switches, Entering Emacs, Top
@section Exiting Emacs
@cindex exiting
@cindex killing Emacs
@cindex suspending
@cindex leaving Emacs
@cindex quitting Emacs
@cindex shrinking XEmacs frame

  There are two commands for exiting Emacs because there are two kinds
of exiting: @dfn{suspending} Emacs and @dfn{killing} Emacs.

  @dfn{Suspending} means stopping Emacs temporarily and returning
control to its parent process (usually a shell), allowing you to resume
editing later in the same Emacs job, with the same buffers, 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.

@table @kbd
@item C-z
Suspend Emacs or iconify a frame
(@code{suspend-emacs-or-iconify-frame}).  If used under the X window
system, shrink the X window containing the Emacs frame to an icon (see
below).
@item C-x C-c
Kill Emacs (@code{save-buffers-kill-emacs}).
@end table

If you use XEmacs under the X window system, @kbd{C-z} shrinks
the X window containing the Emacs frame to an icon.  The Emacs process
is stopped temporarily, and control is returned to the window manager.
If more than one frame is associated with the Emacs process, only the
frame from which you used @kbd{C-z} is iconified.

To activate the "suspended" Emacs, use the appropriate window manager
mouse gestures.  Usually left-clicking on the icon reactivates and
reopens the X window containing the Emacs frame, but the window manager
you use determines what exactly happens.  To actually kill the Emacs
process, use @kbd{C-x C-c} or the @b{Exit XEmacs} item on the @b{File}
menu.

@kindex C-z
@findex suspend-emacs
  To suspend Emacs, type @kbd{C-z} (@code{suspend-emacs}).  This takes
you back to the shell from which you invoked Emacs.  You can resume
Emacs with the shell command @samp{%xemacs} in most common shells.

  On systems that do not support suspending programs, @kbd{C-z} starts
an inferior shell that communicates directly with the terminal.
Emacs waits until you exit the subshell.  (The way to do that is
probably with @kbd{C-d} or @samp{exit}, but it depends on which shell
you use.)  The only way on these systems to get back to the shell from
which Emacs was run (to log out, for example) is to kill Emacs.

  Suspending also fails if you run Emacs under a shell that doesn't
support suspending programs, even if the system itself does support it.
In such a case, you can set the variable @code{cannot-suspend} to a
non-@code{nil} value to force @kbd{C-z} to start an inferior shell.
(One might also describe Emacs's parent shell as ``inferior'' for
failing to support job control properly, but that is a matter of taste.)

  When Emacs communicates directly with an X server and creates its own
dedicated X windows, @kbd{C-z} has a different meaning.  Suspending an
applications that uses its own X windows is not meaningful or useful.
Instead, @kbd{C-z} runs the command @code{iconify-or-deiconify-frame},
which temporarily closes up the selected Emacs frame.
The way to get back to a shell window is with the window manager.

@kindex C-x C-c
@findex save-buffers-kill-emacs
  To kill Emacs, type @kbd{C-x C-c} (@code{save-buffers-kill-emacs}).  A
two-character key is used for this to make it harder to type.  Selecting
the @b{Exit XEmacs} option of the @b{File} menu is an alternate way of
issuing the command.

Unless a numeric argument is used, this command first offers to save any
modified file-visiting buffers.  If you do not save all buffers, you are
asked for reconfirmation with @kbd{yes} before killing Emacs, since any
changes not saved will be lost forever.  If any subprocesses are still
running, @kbd{C-x C-c} asks you to confirm killing them, since killing
Emacs will kill the subprocesses immediately.

  There is no way to restart an Emacs session once you have killed it.
You can, however, arrange for Emacs to record certain session
information, such as which files are visited, when you kill it, so that
the next time you restart Emacs it will try to visit the same files and
so on.
@c @xref{Saving Emacs Sessions}.

  The operating system usually listens for certain special characters
whose meaning is to kill or suspend the program you are running.
@b{This operating system feature is turned off while you are in Emacs.}
The meanings of @kbd{C-z} and @kbd{C-x C-c} as keys in Emacs were
inspired by the use of @kbd{C-z} and @kbd{C-c} on several operating
systems as the characters for stopping or killing a program, but that is
their only relationship with the operating system.  You can customize
these keys to run any commands of your choice (@pxref{Keymaps}).