Entering Emacs
==============

The usual way to invoke Emacs is with the shell command emacs.  From a terminal window running in the X Window System, you can also run Emacs in the background with emacs&; this way, Emacs won't tie up the terminal window, so you can use it to run other shell commands.

When Emacs starts up, the initial frame displays a special buffer named *GNU Emacs*.  This buffer contains some information about Emacs, and includes links to common tasks that might be useful to beginning users.  For instance, activating the Emacs Tutorial link opens the Emacs tutorial; this does the same thing as the command C-h t (help-with-tutorial).  To activate a link, either move point onto it and type RET, or click on it with mouse-1 (the left mouse button).

Using a command line argument, you can tell Emacs to visit one or more specific files as soon as it starts up.  For example, emacs foo.txt starts Emacs with a buffer displaying the contents of the file foo.txt.  This feature exists mainly for compatibility with other editors, which are designed to edit one file at a time: once you are done with that file, you exit the editor, and start it again the next time you need it.

Using Emacs in this way---starting it afresh each time you want to edit a file---is unnecessary and wasteful.  Emacs can visit more than one file in a single editing session, and exiting the Emacs session loses valuable accumulated context, such as the kill ring, registers, undo history, and mark ring.  These features, described later in the manual, are useful for performing edits across multiple files, or continuing edits to a single file.

The recommended way to use Emacs is to start it only once, just after you log in, and do all your editing in the same Emacs session. Each time you edit a file, visit it with the existing Emacs, which eventually has many files in it ready for editing.  See Files, for more information on visiting more than one file.

To edit a file from another program while Emacs is running, you can use the emacsclient helper program to open a file in the already running Emacs.  See Emacs Server.

Emacs accepts other command line arguments that tell it to load certain Lisp files, call certain functions, and so forth.  These features exist mainly for advanced users.  See Emacs Invocation.

If the variable inhibit-startup-screen is non-nil, Emacs does not display the startup screen.  In that case, if one or more files were specified on the command line, Emacs simply displays those files; otherwise, it displays a buffer named *scratch*, which can be used to evaluate Emacs Lisp expressions interactively. See Lisp Interaction.  You can set the variable inhibit-startup-screen using the Customize facility (see Easy Customization), or by editing your initialization file (see Init File). (Note that setting inhibit-startup-screen in site-start.el doesn't work, because the startup screen is set up before reading site-start.el.  See Init File, for information about site-start.el.)

You can also force Emacs to display a file or directory at startup by setting the variable initial-buffer-choice to a non-nil value.  (In that case, even if you specify one or more files on the command line, Emacs opens but does not display them.) The value of initial-buffer-choice can be either the name of the desired file or directory, or t, which means to display the *scratch* buffer.

Exiting Emacs
=============

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

C-z
     On a text terminal, suspend Emacs (suspend-emacs); on a graphical display, iconify (or ``minimize'') the selected frame (iconify-or-deiconify-frame).

Killing Emacs means terminating the Emacs program.  To do this, type C-x C-c (save-buffers-kill-terminal).  A two-character key is used to make it harder to type by accident.  If there are any modified file-visiting buffers when you type C-x C-c, Emacs first offers to save these buffers.  If you do not save them all, it asks for confirmation again, since the unsaved changes will be lost.  Emacs also asks for confirmation if any subprocesses are still running, since killing Emacs will also kill the subprocesses (see Shell).

C-x C-c behaves specially if you are using Emacs as a server. If you type it from a ``client frame'', it closes the client connection.  See Emacs Server.

Emacs can, optionally, record certain session information when you kill it, such as the files you were visiting at the time.  This information is then available the next time you start Emacs. See Saving Emacs Sessions.

If the value of the variable confirm-kill-emacs is non-nil, C-x C-c assumes that its value is a predicate function, and calls that function.  If the result of the function call is non-nil, the session is killed, otherwise Emacs continues to run.  One convenient function to use as the value of confirm-kill-emacs is the function yes-or-no-p.  The default value of confirm-kill-emacs is nil.

To kill Emacs without being prompted about saving, type M-x kill-emacs.

You can ``exit'' Emacs in two other ways.  On a graphical display, you can iconify (or minimize) an Emacs frame; depending on the window system, this either replaces the Emacs frame with a tiny ``icon'' or conceals the frame entirely (see Frames).  On a text-only terminal, you can suspend Emacs; this means stopping the Emacs program temporarily, returning control to its parent process (usually a shell).

On a graphical display, C-z runs the command iconify-or-deiconify-frame, which iconifies the selected Emacs frame.  On a text terminal, C-z runs the command suspend-emacs, which suspends Emacs.

After iconifying or suspending Emacs, you can return to it and continue editing wherever you left off.  The way to do this depends on the window system or shell.  In most common shells, you can resume Emacs after suspending it with the shell command %emacs.

On very old systems that don't support suspending programs, C-z starts an inferior shell that communicates directly with the terminal, and Emacs waits until you exit the subshell.  (The way to exit the subshell is usually C-d or exit.)  On these systems, you can only get back to the shell from which Emacs was run (to log out, for example) when you kill Emacs.  Suspending can also fail if you run Emacs under a shell that doesn't support suspending jobs, even if the system itself does support it.  In this case, you can set the variable cannot-suspend to a non-nil value to force C-z to start an inferior shell.

Text-only terminals usually listen for certain special characters whose meaning is to kill or suspend the program you are running. This terminal 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).