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1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995 Free Software Foundation, Inc.
3 @c See file emacs.texi for copying conditions.
4 @node Entering Emacs, Exiting, Text Characters, Top
5 @chapter Entering and Exiting Emacs
6 @cindex entering Emacs
7 @cindex starting Emacs
9 The usual way to invoke Emacs is with the shell command @command{emacs}.
10 Emacs clears the screen and then displays an initial help message and
11 copyright notice. Some operating systems discard all type-ahead when
12 Emacs starts up; they give Emacs no way to prevent this. Therefore, it
13 is advisable to wait until Emacs clears the screen before typing your
14 first editing command.
16 If you run Emacs from a shell window under the X Window System, run it
17 in the background with @command{emacs&}. This way, Emacs does not tie up
18 the shell window, so you can use that to run other shell commands while
19 Emacs operates its own X windows. You can begin typing Emacs commands
20 as soon as you direct your keyboard input to the Emacs frame.
22 @vindex initial-major-mode
23 When Emacs starts up, it creates a buffer named @samp{*scratch*}.
24 That's the buffer you start out in. The @samp{*scratch*} buffer uses Lisp
25 Interaction mode; you can use it to type Lisp expressions and evaluate
26 them, or you can ignore that capability and simply doodle. (You can
27 specify a different major mode for this buffer by setting the variable
28 @code{initial-major-mode} in your init file. @xref{Init File}.)
30 It is possible to specify files to be visited, Lisp files to be
31 loaded, and functions to be called, by giving Emacs arguments in the
32 shell command line. @xref{Command Arguments}. But we don't recommend
33 doing this. The feature exists mainly for compatibility with other
34 editors.
36 Many other editors are designed to be started afresh each time you
37 want to edit. You edit one file and then exit the editor. The next
38 time you want to edit either another file or the same one, you must run
39 the editor again. With these editors, it makes sense to use a
40 command-line argument to say which file to edit.
42 But starting a new Emacs each time you want to edit a different file
43 does not make sense. For one thing, this would be annoyingly slow.
44 For another, this would fail to take advantage of Emacs's ability to
45 visit more than one file in a single editing session. And it would
46 lose the other accumulated context, such as the kill ring, registers,
47 undo history, and mark ring.
49 The recommended way to use GNU Emacs is to start it only once, just
50 after you log in, and do all your editing in the same Emacs session.
51 Each time you want to edit a different file, you visit it with the
52 existing Emacs, which eventually comes to have many files in it ready
53 for editing. Usually you do not kill the Emacs until you are about to
54 log out. @xref{Files}, for more information on visiting more than one
55 file.
57 If you want to edit a file from another program and already have
58 Emacs running, you can use the @command{emacsclient} program to open a
59 file in the already running Emacs. @xref{Emacs Server}, for more
60 information on editing files with Emacs from other programs.
62 @node Exiting, Basic, Entering Emacs, Top
63 @section Exiting Emacs
64 @cindex exiting
65 @cindex killing Emacs
66 @cindex suspending
67 @cindex leaving Emacs
68 @cindex quitting Emacs
70 There are two commands for exiting Emacs because there are two kinds
71 of exiting: @dfn{suspending} Emacs and @dfn{killing} Emacs.
73 @dfn{Suspending} means stopping Emacs temporarily and returning
74 control to its parent process (usually a shell), allowing you to resume
75 editing later in the same Emacs job, with the same buffers, same kill
76 ring, same undo history, and so on. This is the usual way to exit.
78 @dfn{Killing} Emacs means destroying the Emacs job. You can run Emacs
79 again later, but you will get a fresh Emacs; there is no way to resume
80 the same editing session after it has been killed.
82 @table @kbd
83 @item C-z
84 Suspend Emacs (@code{suspend-emacs}) or iconify a frame
85 (@code{iconify-or-deiconify-frame}).
86 @item C-x C-c
87 Kill Emacs (@code{save-buffers-kill-emacs}).
88 @end table
90 @kindex C-z
91 @findex suspend-emacs
92 To suspend Emacs, type @kbd{C-z} (@code{suspend-emacs}). This takes
93 you back to the shell from which you invoked Emacs. You can resume
94 Emacs with the shell command @command{%emacs} in most common shells.
96 On systems that do not support suspending programs, @kbd{C-z} starts
97 an inferior shell that communicates directly with the terminal.
98 Emacs waits until you exit the subshell. (The way to do that is
99 probably with @kbd{C-d} or @command{exit}, but it depends on which shell
100 you use.) The only way on these systems to get back to the shell from
101 which Emacs was run (to log out, for example) is to kill Emacs.
103 Suspending also fails if you run Emacs under a shell that doesn't
104 support suspending programs, even if the system itself does support it.
105 In such a case, you can set the variable @code{cannot-suspend} to a
106 non-@code{nil} value to force @kbd{C-z} to start an inferior shell.
107 (One might also describe Emacs's parent shell as ``inferior'' for
108 failing to support job control properly, but that is a matter of taste.)
110 When Emacs communicates directly with an X server and creates its own
111 dedicated X windows, @kbd{C-z} has a different meaning. Suspending an
112 application that uses its own X windows is not meaningful or useful.
113 Instead, @kbd{C-z} runs the command @code{iconify-or-deiconify-frame},
114 which temporarily iconifies (or ``minimizes'') the selected Emacs
115 frame (@pxref{Frames}). Then you can use the window manager to get
116 back to a shell window.
118 @kindex C-x C-c
119 @findex save-buffers-kill-emacs
120 To exit and kill Emacs, type @kbd{C-x C-c}
121 (@code{save-buffers-kill-emacs}). A two-character key is used for
122 this to make it harder to type by accident. This command first offers
123 to save any modified file-visiting buffers. If you do not save them
124 all, it asks for reconfirmation with @kbd{yes} before killing Emacs,
125 since any changes not saved will be lost forever. Also, if any
126 subprocesses are still running, @kbd{C-x C-c} asks for confirmation
127 about them, since killing Emacs will also kill the subprocesses.
129 @vindex confirm-kill-emacs
130 If the value of the variable @code{confirm-kill-emacs} is
131 non-@code{nil}, @kbd{C-x C-c} assumes that its value is a predicate
132 function, and calls that function. If the result is non-@code{nil}, the
133 session is killed, otherwise Emacs continues to run. One convenient
134 function to use as the value of @code{confirm-kill-emacs} is the
135 function @code{yes-or-no-p}. The default value of
136 @code{confirm-kill-emacs} is @code{nil}.
138 There is no way to resume an Emacs session once you have killed it.
139 You can, however, arrange for Emacs to record certain session
140 information when you kill it, such as which files are visited, so that
141 the next time you start Emacs it will try to visit the same files and
142 so on. @xref{Saving Emacs Sessions}.
144 The operating system usually listens for certain special characters
145 whose meaning is to kill or suspend the program you are running.
146 @b{This operating system feature is turned off while you are in Emacs.}
147 The meanings of @kbd{C-z} and @kbd{C-x C-c} as keys in Emacs were
148 inspired by the use of @kbd{C-z} and @kbd{C-c} on several operating
149 systems as the characters for stopping or killing a program, but that is
150 their only relationship with the operating system. You can customize
151 these keys to run any commands of your choice (@pxref{Keymaps}).