man/entering.texi

   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
   8
   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.
  15
  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.
  21
  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}.)
  29
  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.
  35
  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.
  41
  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.
  48
  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.
  56
  57 @node Exiting, Basic, Entering Emacs, Top
  58 @section Exiting Emacs
  59 @cindex exiting
  60 @cindex killing Emacs
  61 @cindex suspending
  62 @cindex leaving Emacs
  63 @cindex quitting Emacs
  64
  65   There are two commands for exiting Emacs because there are two kinds
  66 of exiting: @dfn{suspending} Emacs and @dfn{killing} Emacs.
  67
  68   @dfn{Suspending} means stopping Emacs temporarily and returning
  69 control to its parent process (usually a shell), allowing you to resume
  70 editing later in the same Emacs job, with the same buffers, same kill
  71 ring, same undo history, and so on.  This is the usual way to exit.
  72
  73   @dfn{Killing} Emacs means destroying the Emacs job.  You can run Emacs
  74 again later, but you will get a fresh Emacs; there is no way to resume
  75 the same editing session after it has been killed.
  76
  77 @table @kbd
  78 @item C-z
  79 Suspend Emacs (@code{suspend-emacs}) or iconify a frame
  80 (@code{iconify-or-deiconify-frame}).
  81 @item C-x C-c
  82 Kill Emacs (@code{save-buffers-kill-emacs}).
  83 @end table
  84
  85 @kindex C-z
  86 @findex suspend-emacs
  87   To suspend Emacs, type @kbd{C-z} (@code{suspend-emacs}).  This takes
  88 you back to the shell from which you invoked Emacs.  You can resume
  89 Emacs with the shell command @command{%emacs} in most common shells.
  90
  91   On systems that do not support suspending programs, @kbd{C-z} starts
  92 an inferior shell that communicates directly with the terminal.
  93 Emacs waits until you exit the subshell.  (The way to do that is
  94 probably with @kbd{C-d} or @command{exit}, but it depends on which shell
  95 you use.)  The only way on these systems to get back to the shell from
  96 which Emacs was run (to log out, for example) is to kill Emacs.
  97
  98   Suspending also fails if you run Emacs under a shell that doesn't
  99 support suspending programs, even if the system itself does support it.
 100 In such a case, you can set the variable @code{cannot-suspend} to a
 101 non-@code{nil} value to force @kbd{C-z} to start an inferior shell.
 102 (One might also describe Emacs's parent shell as ``inferior'' for
 103 failing to support job control properly, but that is a matter of taste.)
 104
 105   When Emacs communicates directly with an X server and creates its own
 106 dedicated X windows, @kbd{C-z} has a different meaning.  Suspending an
 107 application that uses its own X windows is not meaningful or useful.
 108 Instead, @kbd{C-z} runs the command @code{iconify-or-deiconify-frame},
 109 which temporarily iconifies (or ``minimizes'') the selected Emacs
 110 frame (@pxref{Frames}).  Then you can use the window manager to get
 111 back to a shell window.
 112
 113 @kindex C-x C-c
 114 @findex save-buffers-kill-emacs
 115   To exit and kill Emacs, type @kbd{C-x C-c}
 116 (@code{save-buffers-kill-emacs}).  A two-character key is used for
 117 this to make it harder to type by accident.  This command first offers
 118 to save any modified file-visiting buffers.  If you do not save them
 119 all, it asks for reconfirmation with @kbd{yes} before killing Emacs,
 120 since any changes not saved will be lost forever.  Also, if any
 121 subprocesses are still running, @kbd{C-x C-c} asks for confirmation
 122 about them, since killing Emacs will also kill the subprocesses.
 123
 124 @vindex confirm-kill-emacs
 125   If the value of the variable @code{confirm-kill-emacs} is
 126 non-@code{nil}, @kbd{C-x C-c} assumes that its value is a predicate
 127 function, and calls that function.  If the result is non-@code{nil}, the
 128 session is killed, otherwise Emacs continues to run.  One convenient
 129 function to use as the value of @code{confirm-kill-emacs} is the
 130 function @code{yes-or-no-p}.  The default value of
 131 @code{confirm-kill-emacs} is @code{nil}.
 132
 133   There is no way to resume an Emacs session once you have killed it.
 134 You can, however, arrange for Emacs to record certain session
 135 information when you kill it, such as which files are visited, so that
 136 the next time you start Emacs it will try to visit the same files and
 137 so on.  @xref{Saving Emacs Sessions}.
 138
 139   The operating system usually listens for certain special characters
 140 whose meaning is to kill or suspend the program you are running.
 141 @b{This operating system feature is turned off while you are in Emacs.}
 142 The meanings of @kbd{C-z} and @kbd{C-x C-c} as keys in Emacs were
 143 inspired by the use of @kbd{C-z} and @kbd{C-c} on several operating
 144 systems as the characters for stopping or killing a program, but that is
 145 their only relationship with the operating system.  You can customize
 146 these keys to run any commands of your choice (@pxref{Keymaps}).