(calc-graph-lookup): Avoid assignment to free variable `var'.

[bpt/emacs.git] / doc / emacs / entering.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 2001, 2002, 2003,
@c   2004, 2005, 2006, 2007, 2008, 2009  Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@iftex
@chapter Entering and Exiting Emacs

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

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@end ifnottex

@node Entering Emacs, Exiting, Commands, Top
@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 in the X Window
System, you can also run Emacs in the background with
@command{emacs&}; this way, Emacs won't tie up the terminal window, so
you can use it to run other shell commands.

@cindex startup screen
  When Emacs starts up, the initial frame displays a special buffer
named @samp{*GNU Emacs*}.  This buffer contains some information about
Emacs, and includes @dfn{links} to common tasks that might be useful
to 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 specific 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 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.  @xref{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 @command{emacsclient} helper program to open a file in the
already running Emacs.  @xref{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.  @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 @samp{*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{Note that 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
non-@code{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 @code{initial-buffer-choice} can be either the name of
the desired file or directory, or @code{t}, which means to display the
@samp{*scratch*} buffer.

@node Exiting, Basic, Entering Emacs, Top
@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 (@code{suspend-emacs}); on a
graphical display, iconify (or ``minimize'') the selected frame
(@code{iconify-or-deiconify-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 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}.

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

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

@kindex C-z
@findex iconify-or-deiconify-frame
@findex suspend-emacs
  On a graphical display, @kbd{C-z} runs the command
@code{iconify-or-deiconify-frame}, which iconifies the selected Emacs
frame.  On a text terminal, @kbd{C-z} runs the command
@code{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 @command{%emacs}.

@vindex cannot-suspend
  On very old systems that don't support suspending programs,
@kbd{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 @kbd{C-d} or @command{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 @code{cannot-suspend} to a non-@code{nil} value
to force @kbd{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.
@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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