Entering and Exiting Emacs
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The usual way to invoke XEmacs is to type xemacs 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 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.

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 *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.  (You can specify a different major mode for this buffer by setting the variable initial-major-mode in your init file.  See 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.  See 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.  See Files, for more information on visiting more than one file.

Exiting Emacs
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There are two commands for exiting Emacs because there are two kinds of exiting: suspending Emacs and killing Emacs.

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.

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.

C-z
     Suspend Emacs or iconify a frame (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).

C-x C-c
     Kill Emacs (save-buffers-kill-emacs).

If you use XEmacs under the X window system, 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 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 C-x C-c or the Exit XEmacs item on the File menu.

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

On systems that do not support suspending programs, 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 C-d or 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 cannot-suspend to a non-nil value to force 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, C-z has a different meaning.  Suspending an applications that uses its own X windows is not meaningful or useful. Instead, C-z runs the command 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.

To kill Emacs, type C-x C-c (save-buffers-kill-emacs).  A two-character key is used for this to make it harder to type.  Selecting the Exit XEmacs option of the 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 yes before killing Emacs, since any changes not saved will be lost forever.  If any subprocesses are still running, 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.

The operating system usually listens for certain special characters whose meaning is to kill or suspend the program you are running. This operating system feature is turned off while you are in Emacs. The meanings of C-z and C-x C-c as keys in Emacs were inspired by the use of C-z and 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 (see Keymaps).