emacs/doc/emacs/entering.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985-1987, 1993-1995, 2001-2019 Free Software
@c Foundation, Inc.
@c See file emacs.texi for copying conditions.
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@chapter Entering and Exiting Emacs

  This chapter explains how to enter Emacs, and how to exit it.
@end iftex

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@node Entering Emacs
@section Entering Emacs
@cindex entering Emacs
@cindex starting Emacs

  The usual way to invoke Emacs is with the shell command
@command{emacs}.  From a terminal window running a Unix shell on a GUI
terminal, you can run Emacs in the background with @kbd{emacs &}; this
way, Emacs won't tie up the terminal window, so you can use it to run
other shell commands.  (For comparable methods of starting Emacs on
MS-Windows, see @ref{Windows Startup}.)

@cindex startup screen
  When Emacs starts up, the initial frame displays a special buffer
named @samp{*GNU Emacs*}.  This @dfn{startup screen} contains
information about Emacs and @dfn{links} to common tasks that are
useful for beginning users.  For instance, activating the @samp{Emacs
Tutorial} link opens the Emacs tutorial; this does the same thing as
the command @kbd{C-h t} (@code{help-with-tutorial}).  To activate a
link, either move point onto it and type @kbd{@key{RET}}, or click on
it with @kbd{mouse-1} (the left mouse button).

  Using a command line argument, you can tell Emacs to visit one or
more files as soon as it starts up.  For example, @command{emacs
foo.txt} starts Emacs with a buffer displaying the contents of the
file @samp{foo.txt}.  This feature exists mainly for compatibility
with other editors, which are designed to be launched from the shell
for short editing sessions.  If you call Emacs this way, the initial
frame is split into two windows---one showing the specified file, and
the other showing the startup screen.  @xref{Windows}.

  Generally, it is unnecessary and wasteful to start Emacs afresh each
time you want to edit a file.  The recommended way to use Emacs is to
start it just once, just after you log in, and do all your editing in
the same Emacs session.  @xref{Files}, for information on visiting
more than one file.  If you use Emacs this way, the Emacs session
accumulates valuable context, such as the kill ring, registers, undo
history, and mark ring data, which together make editing more
convenient.  These features are described later in the manual.

  To edit a file from another program while Emacs is running, you can
use the @command{emacsclient} helper program to open a file in the
existing Emacs session.  @xref{Emacs Server}.

  Emacs accepts other command line arguments that tell it to load
certain Lisp files, where to put the initial frame, and so forth.
@xref{Emacs Invocation}.

@vindex inhibit-startup-screen
  If the variable @code{inhibit-startup-screen} is non-@code{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 @file{*scratch*},
which can be used to evaluate Emacs Lisp expressions interactively.
@xref{Lisp Interaction}.  You can set the variable
@code{inhibit-startup-screen} using the Customize facility
(@pxref{Easy Customization}), or by editing your initialization file
(@pxref{Init File}).@footnote{Setting @code{inhibit-startup-screen} in
@file{site-start.el} doesn't work, because the startup screen is set
up before reading @file{site-start.el}.  @xref{Init File}, for
information about @file{site-start.el}.}

  You can also force Emacs to display a file or directory at startup
by setting the variable @code{initial-buffer-choice} to a string
naming that file or directory.  The value of
@code{initial-buffer-choice} may also be a function (of no arguments)
that should return a buffer which is then displayed.
@ignore
@c I do not think this should be mentioned.  AFAICS it is just a dodge
@c around inhibit-startup-screen not being settable on a site-wide basis.
@code{initial-buffer-choice} may also be @code{t} in which case the
@file{*scratch*} buffer will be shown.
@end ignore
If @code{initial-buffer-choice} is non-@code{nil}, then if you specify
any files on the command line, Emacs still visits them, but does not
display them initially.

@node Exiting
@section Exiting Emacs
@cindex exiting
@cindex killing Emacs
@cindex leaving Emacs
@cindex quitting Emacs

@table @kbd
@item C-x C-c
Kill Emacs (@code{save-buffers-kill-terminal}).
@item C-z
On a text terminal, suspend Emacs; on a graphical display,
iconify (or ``minimize'') the selected frame (@code{suspend-frame}).
@end table

@kindex C-x C-c
@findex save-buffers-kill-terminal
  @dfn{Killing} Emacs means terminating the Emacs program.  To do
this, type @kbd{C-x C-c} (@code{save-buffers-kill-terminal}).  A
two-character key sequence is used to make it harder to type by
accident.  If there are any modified file-visiting buffers when you
type @kbd{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 (@pxref{Shell}).

  @kbd{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.  @xref{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.
@xref{Saving Emacs Sessions}.

@vindex confirm-kill-emacs
  If the value of the variable @code{confirm-kill-emacs} is
non-@code{nil}, @kbd{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-@code{nil}, the session is killed, otherwise Emacs continues to
run.  One convenient function to use as the value of
@code{confirm-kill-emacs} is the function @code{yes-or-no-p}.  The
default value of @code{confirm-kill-emacs} is @code{nil}.

@vindex confirm-kill-processes
  If the value of the variable @code{confirm-kill-processes} is
@code{nil}, @kbd{C-x C-c} does not ask for confirmation before killing
subprocesses started by Emacs.  The value is @code{t} by default.

  To further customize what happens when Emacs is exiting, see
@ref{Killing Emacs,,, elisp, The GNU Emacs Lisp Reference Manual}.

@findex kill-emacs
  To kill Emacs without being prompted about saving, type @kbd{M-x
kill-emacs}.

@kindex C-z
@findex suspend-frame
@cindex minimizing
@cindex iconifying
@cindex suspending
  @kbd{C-z} runs the command @code{suspend-frame}.  On a graphical
display, this command @dfn{minimizes} (or @dfn{iconifies}) the
selected Emacs frame, hiding it in a way that lets you bring it back
later (exactly how this hiding occurs depends on the window system).
On a text terminal, the @kbd{C-z} command @dfn{suspends} Emacs,
stopping the program temporarily and returning control to the parent
process (usually a shell); in most shells, you can resume Emacs after
suspending it with the shell command @command{%emacs}.

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

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