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[Emacs-diffs] Changes to os.texi


From: Glenn Morris
Subject: [Emacs-diffs] Changes to os.texi
Date: Thu, 06 Sep 2007 04:13:43 +0000

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Glenn Morris <gm>       07/09/06 04:13:42

Index: os.texi
===================================================================
RCS file: os.texi
diff -N os.texi
--- os.texi     13 Jun 2007 00:24:15 -0000      1.108
+++ /dev/null   1 Jan 1970 00:00:00 -0000
@@ -1,2004 +0,0 @@
address@hidden -*-texinfo-*-
address@hidden This is part of the GNU Emacs Lisp Reference Manual.
address@hidden Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 
2001,
address@hidden   2002, 2003, 2004, 2005, 2006, 2007  Free Software Foundation, 
Inc.
address@hidden See the file elisp.texi for copying conditions.
address@hidden ../info/os
address@hidden System Interface, Antinews, Display, Top
address@hidden Operating System Interface
-
-  This chapter is about starting and getting out of Emacs, access to
-values in the operating system environment, and terminal input, output,
-and flow control.
-
-  @xref{Building Emacs}, for related information.  See also
address@hidden, for additional operating system status information
-pertaining to the terminal and the screen.
-
address@hidden
-* Starting Up::         Customizing Emacs startup processing.
-* Getting Out::         How exiting works (permanent or temporary).
-* System Environment::  Distinguish the name and kind of system.
-* User Identification:: Finding the name and user id of the user.
-* Time of Day::                Getting the current time.
-* Time Conversion::     Converting a time from numeric form
-                          to calendrical data, and vice versa).
-* Time Parsing::        Converting a time from numeric form to text
-                          and vice versa.
-* Processor Run Time::  Getting the run time used by Emacs.
-* Time Calculations::   Adding, subtracting, comparing times, etc.
-* Timers::             Setting a timer to call a function at a certain time.
-* Idle Timers::         Setting a timer to call a function when Emacs has
-                          been idle for a certain length of time.
-* Terminal Input::      Accessing and recording terminal input.
-* Terminal Output::     Controlling and recording terminal output.
-* Sound Output::        Playing sounds on the computer's speaker.
-* X11 Keysyms::         Operating on key symbols for X Windows
-* Batch Mode::          Running Emacs without terminal interaction.
-* Session Management::  Saving and restoring state with X Session Management.
address@hidden menu
-
address@hidden Starting Up
address@hidden Starting Up Emacs
-
-  This section describes what Emacs does when it is started, and how you
-can customize these actions.
-
address@hidden
-* Startup Summary::         Sequence of actions Emacs performs at startup.
-* Init File::               Details on reading the init file (@file{.emacs}).
-* Terminal-Specific::       How the terminal-specific Lisp file is read.
-* Command-Line Arguments::  How command-line arguments are processed,
-                              and how you can customize them.
address@hidden menu
-
address@hidden Startup Summary
address@hidden Summary: Sequence of Actions at Startup
address@hidden initialization of Emacs
address@hidden startup of Emacs
address@hidden @file{startup.el}
-
-   The order of operations performed (in @file{startup.el}) by Emacs when
-it is started up is as follows:
-
address@hidden
address@hidden
-It adds subdirectories to @code{load-path}, by running the file named
address@hidden in each directory in the list.  Normally this file
-adds the directory's subdirectories to the list, and these will be
-scanned in their turn.  The files @file{subdirs.el} are normally
-generated automatically by Emacs installation.
-
address@hidden
-It sets the language environment and the terminal coding system,
-if requested by environment variables such as @code{LANG}.
-
address@hidden
-It loads the initialization library for the window system, if you are
-using a window system.  This library's name is
address@hidden/@var{windowsystem}-win.el}.
-
address@hidden
-It processes the initial options.  (Some of them are handled
-even earlier than this.)
-
address@hidden
-It initializes the window frame and faces, if appropriate.
-
address@hidden
-It runs the normal hook @code{before-init-hook}.
-
address@hidden
-It loads the library @file{site-start} (if any), unless the option
address@hidden (or @samp{--no-site-file}) was specified.  The library's file
-name is usually @file{site-start.el}.
address@hidden @file{site-start.el}
-
address@hidden
-It loads your init file (usually @file{~/.emacs}), unless the option
address@hidden (or @samp{--no-init-file}), @samp{-Q}, or @samp{--batch} was
-specified on the command line.  The @samp{-u} option can specify
-another user whose home directory should be used instead of @file{~}.
-
address@hidden
-It loads the library @file{default} (if any), unless
address@hidden is address@hidden  (This is not done in
address@hidden mode, or if @samp{-Q} or @samp{-q} was specified on the
-command line.)  The library's file name is usually @file{default.el}.
address@hidden @file{default.el}
-
address@hidden
-It runs the normal hook @code{after-init-hook}.
-
address@hidden
-It sets the major mode according to @code{initial-major-mode}, provided
-the buffer @samp{*scratch*} is still current and still in Fundamental
-mode.
-
address@hidden
-It loads the terminal-specific Lisp file, if any, except when in batch
-mode or using a window system.
-
address@hidden
-It displays the initial echo area message, unless you have suppressed
-that with @code{inhibit-startup-echo-area-message}.
-
address@hidden
-It processes the action arguments from the command line.
-
address@hidden
-It runs @code{emacs-startup-hook} and then @code{term-setup-hook}.
-
address@hidden
-It calls @code{frame-notice-user-settings}, which modifies the
-parameters of the selected frame according to whatever the init files
-specify.
-
address@hidden
-It runs @code{window-setup-hook}.  @xref{Window Systems}.
-
address@hidden
-It displays copyleft, nonwarranty, and basic use information, provided
-the value of @code{inhibit-startup-message} is @code{nil}, you didn't
-specify @samp{--no-splash} or @samp{-Q}.
address@hidden enumerate
-
address@hidden inhibit-startup-message
-This variable inhibits the initial startup messages (the nonwarranty,
-etc.).  If it is address@hidden, then the messages are not printed.
-
-This variable exists so you can set it in your personal init file, once
-you are familiar with the contents of the startup message.  Do not set
-this variable in the init file of a new user, or in a way that affects
-more than one user, because that would prevent new users from receiving
-the information they are supposed to see.
address@hidden defopt
-
address@hidden inhibit-startup-echo-area-message
-This variable controls the display of the startup echo area message.
-You can suppress the startup echo area message by adding text with this
-form to your init file:
-
address@hidden
-(setq inhibit-startup-echo-area-message
-      "@var{your-login-name}")
address@hidden example
-
-Emacs explicitly checks for an expression as shown above in your init
-file; your login name must appear in the expression as a Lisp string
-constant.  Other methods of setting
address@hidden to the same value do not
-inhibit the startup message.
-
-This way, you can easily inhibit the message for yourself if you wish,
-but thoughtless copying of your init file will not inhibit the message
-for someone else.
address@hidden defopt
-
address@hidden Init File
address@hidden The Init File, @file{.emacs}
address@hidden init file
address@hidden @file{.emacs}
-
-  When you start Emacs, it normally attempts to load your @dfn{init
-file}, a file in your home directory.  Its normal name is
address@hidden, but you can also call it @file{.emacs.el}.
-Alternatively, you can use a file named @file{init.el} in a
-subdirectory @file{.emacs.d}.  Whichever place you use, you can also
-compile the file (@pxref{Byte Compilation}); then the actual file
-loaded will be @file{.emacs.elc} or @file{init.elc}.
-
-  The command-line switches @samp{-q}, @samp{-Q}, and @samp{-u}
-control whether and where to find the init file; @samp{-q} (and the
-stronger @samp{-Q}) says not to load an init file, while @samp{-u
address@hidden says to load @var{user}'s init file instead of yours.
address@hidden Emacs,,, emacs, The GNU Emacs Manual}.  If neither
-option is specified, Emacs uses the @code{LOGNAME} environment
-variable, or the @code{USER} (most systems) or @code{USERNAME} (MS
-systems) variable, to find your home directory and thus your init
-file; this way, even if you have su'd, Emacs still loads your own init
-file.  If those environment variables are absent, though, Emacs uses
-your user-id to find your home directory.
-
address@hidden default init file
-  A site may have a @dfn{default init file}, which is the library
-named @file{default.el}.  Emacs finds the @file{default.el} file
-through the standard search path for libraries (@pxref{How Programs Do
-Loading}).  The Emacs distribution does not come with this file; sites
-may provide one for local customizations.  If the default init file
-exists, it is loaded whenever you start Emacs, except in batch mode or
-if @samp{-q} (or @samp{-Q}) is specified.  But your own personal init
-file, if any, is loaded first; if it sets @code{inhibit-default-init}
-to a address@hidden value, then Emacs does not subsequently load the
address@hidden file.
-
-  Another file for site-customization is @file{site-start.el}.  Emacs
-loads this @emph{before} the user's init file.  You can inhibit the
-loading of this file with the option @samp{--no-site-file}.
-
address@hidden site-run-file
-This variable specifies the site-customization file to load before the
-user's init file.  Its normal value is @code{"site-start"}.  The only
-way you can change it with real effect is to do so before dumping
-Emacs.
address@hidden defvar
-
-  @xref{Init Examples,, Init File Examples, emacs, The GNU Emacs Manual}, for
-examples of how to make various commonly desired customizations in your
address@hidden file.
-
address@hidden inhibit-default-init
-This variable prevents Emacs from loading the default initialization
-library file for your session of Emacs.  If its value is address@hidden,
-then the default library is not loaded.  The default value is
address@hidden
address@hidden defopt
-
address@hidden before-init-hook
-This normal hook is run, once, just before loading all the init files
-(the user's init file, @file{default.el}, and/or @file{site-start.el}).
-(The only way to change it with real effect is before dumping Emacs.)
address@hidden defvar
-
address@hidden after-init-hook
-This normal hook is run, once, just after loading all the init files
-(the user's init file, @file{default.el}, and/or @file{site-start.el}),
-before loading the terminal-specific library and processing the
-command-line action arguments.
address@hidden defvar
-
address@hidden emacs-startup-hook
-This normal hook is run, once, just after handling the command line
-arguments, just before @code{term-setup-hook}.
address@hidden defvar
-
address@hidden user-init-file
-This variable holds the absolute file name of the user's init file.  If the
-actual init file loaded is a compiled file, such as @file{.emacs.elc},
-the value refers to the corresponding source file.
address@hidden defvar
-
address@hidden user-emacs-directory
-This variable holds the name of the @file{.emacs.d} directory.  It is
-ordinarily @file{~/.emacs.d}, but differs on some platforms.
address@hidden defvar
-
address@hidden Terminal-Specific
address@hidden Terminal-Specific Initialization
address@hidden terminal-specific initialization
-
-  Each terminal type can have its own Lisp library that Emacs loads when
-run on that type of terminal.  The library's name is constructed by
-concatenating the value of the variable @code{term-file-prefix} and the
-terminal type (specified by the environment variable @code{TERM}).
-Normally, @code{term-file-prefix} has the value
address@hidden"term/"}; changing this is not recommended.  Emacs finds the file
-in the normal manner, by searching the @code{load-path} directories, and
-trying the @samp{.elc} and @samp{.el} suffixes.
-
address@hidden Termcap
-  The usual function of a terminal-specific library is to enable
-special keys to send sequences that Emacs can recognize.  It may also
-need to set or add to @code{function-key-map} if the Termcap or
-Terminfo entry does not specify all the terminal's function keys.
address@hidden Input}.
-
-  When the name of the terminal type contains a hyphen, and no library
-is found whose name is identical to the terminal's name, Emacs strips
-from the terminal's name the last hyphen and everything that follows
-it, and tries again.  This process is repeated until Emacs finds a
-matching library or until there are no more hyphens in the name (the
-latter means the terminal doesn't have any library specific to it).
-Thus, for example, if there are no @samp{aaa-48} and @samp{aaa-30}
-libraries, Emacs will try the same library @file{term/aaa.el} for
-terminal types @samp{aaa-48} and @samp{aaa-30-rv}.  If necessary, the
-library can evaluate @code{(getenv "TERM")} to find the full name of
-the terminal address@hidden
-
-  Your init file can prevent the loading of the
-terminal-specific library by setting the variable
address@hidden to @code{nil}.  This feature is useful when
-experimenting with your own peculiar customizations.
-
-  You can also arrange to override some of the actions of the
-terminal-specific library by setting the variable
address@hidden  This is a normal hook which Emacs runs using
address@hidden at the end of Emacs initialization, after loading both
-your init file and any terminal-specific libraries.  You can
-use this variable to define initializations for terminals that do not
-have their own libraries.  @xref{Hooks}.
-
address@hidden term-file-prefix
address@hidden @code{TERM} environment variable
-If the @code{term-file-prefix} variable is address@hidden, Emacs loads
-a terminal-specific initialization file as follows:
-
address@hidden
-(load (concat term-file-prefix (getenv "TERM")))
address@hidden example
-
address@hidden
-You may set the @code{term-file-prefix} variable to @code{nil} in your
-init file if you do not wish to load the
-terminal-initialization file.  To do this, put the following in
-your init file: @code{(setq term-file-prefix nil)}.
-
-On MS-DOS, if the environment variable @code{TERM} is not set, Emacs
-uses @samp{internal} as the terminal type.
address@hidden defvar
-
address@hidden term-setup-hook
-This variable is a normal hook that Emacs runs after loading your
-init file, the default initialization file (if any) and the
-terminal-specific Lisp file.
-
-You can use @code{term-setup-hook} to override the definitions made by a
-terminal-specific file.
address@hidden defvar
-
-  See @code{window-setup-hook} in @ref{Window Systems}, for a related
-feature.
-
address@hidden Command-Line Arguments
address@hidden Command-Line Arguments
address@hidden command-line arguments
-
-  You can use command-line arguments to request various actions when you
-start Emacs.  Since you do not need to start Emacs more than once per
-day, and will often leave your Emacs session running longer than that,
-command-line arguments are hardly ever used.  As a practical matter, it
-is best to avoid making the habit of using them, since this habit would
-encourage you to kill and restart Emacs unnecessarily often.  These
-options exist for two reasons: to be compatible with other editors (for
-invocation by other programs) and to enable shell scripts to run
-specific Lisp programs.
-
-  This section describes how Emacs processes command-line arguments,
-and how you can customize them.
-
address@hidden
-  (Note that some other editors require you to start afresh each time
-you want to edit a file.  With this kind of editor, you will probably
-specify the file as a command-line argument.  The recommended way to
-use GNU Emacs is to start it only once, just after you log in, and do
-all your editing in the same Emacs process.  Each time you want to edit
-a different file, you visit it with the existing Emacs, which eventually
-comes to have many files in it ready for editing.  Usually you do not
-kill the Emacs until you are about to log out.)
address@hidden ignore
-
address@hidden command-line
-This function parses the command line that Emacs was called with,
-processes it, loads the user's init file and displays the
-startup messages.
address@hidden defun
-
address@hidden command-line-processed
-The value of this variable is @code{t} once the command line has been
-processed.
-
-If you redump Emacs by calling @code{dump-emacs}, you may wish to set
-this variable to @code{nil} first in order to cause the new dumped Emacs
-to process its new command-line arguments.
address@hidden defvar
-
address@hidden command-switch-alist
address@hidden switches on command line
address@hidden options on command line
address@hidden command-line options
-The value of this variable is an alist of user-defined command-line
-options and associated handler functions.  This variable exists so you
-can add elements to it.
-
-A @dfn{command-line option} is an argument on the command line, which
-has the form:
-
address@hidden
address@hidden
address@hidden example
-
-The elements of the @code{command-switch-alist} look like this:
-
address@hidden
-(@var{option} . @var{handler-function})
address@hidden example
-
-The @sc{car}, @var{option}, is a string, the name of a command-line
-option (not including the initial hyphen).  The @var{handler-function}
-is called to handle @var{option}, and receives the option name as its
-sole argument.
-
-In some cases, the option is followed in the command line by an
-argument.  In these cases, the @var{handler-function} can find all the
-remaining command-line arguments in the variable
address@hidden  (The entire list of command-line
-arguments is in @code{command-line-args}.)
-
-The command-line arguments are parsed by the @code{command-line-1}
-function in the @file{startup.el} file.  See also @ref{Emacs
-Invocation, , Command Line Arguments for Emacs Invocation, emacs, The
-GNU Emacs Manual}.
address@hidden defvar
-
address@hidden command-line-args
-The value of this variable is the list of command-line arguments passed
-to Emacs.
address@hidden defvar
-
address@hidden command-line-functions
-This variable's value is a list of functions for handling an
-unrecognized command-line argument.  Each time the next argument to be
-processed has no special meaning, the functions in this list are called,
-in order of appearance, until one of them returns a address@hidden
-value.
-
-These functions are called with no arguments.  They can access the
-command-line argument under consideration through the variable
address@hidden, which is bound temporarily at this point.  The remaining
-arguments (not including the current one) are in the variable
address@hidden
-
-When a function recognizes and processes the argument in @code{argi}, it
-should return a address@hidden value to say it has dealt with that
-argument.  If it has also dealt with some of the following arguments, it
-can indicate that by deleting them from @code{command-line-args-left}.
-
-If all of these functions return @code{nil}, then the argument is used
-as a file name to visit.
address@hidden defvar
-
address@hidden Getting Out
address@hidden Getting Out of Emacs
address@hidden exiting Emacs
-
-  There are two ways to get out of Emacs: you can kill the Emacs job,
-which exits permanently, or you can suspend it, which permits you to
-reenter the Emacs process later.  As a practical matter, you seldom kill
-Emacs---only when you are about to log out.  Suspending is much more
-common.
-
address@hidden
-* Killing Emacs::        Exiting Emacs irreversibly.
-* Suspending Emacs::     Exiting Emacs reversibly.
address@hidden menu
-
address@hidden Killing Emacs
address@hidden  node-name,  next,  previous,  up
address@hidden Killing Emacs
address@hidden killing Emacs
-
-  Killing Emacs means ending the execution of the Emacs process.  The
-parent process normally resumes control.  The low-level primitive for
-killing Emacs is @code{kill-emacs}.
-
address@hidden kill-emacs &optional exit-data
-This function exits the Emacs process and kills it.
-
-If @var{exit-data} is an integer, then it is used as the exit status
-of the Emacs process.  (This is useful primarily in batch operation; see
address@hidden Mode}.)
-
-If @var{exit-data} is a string, its contents are stuffed into the
-terminal input buffer so that the shell (or whatever program next reads
-input) can read them.
address@hidden defun
-
-  All the information in the Emacs process, aside from files that have
-been saved, is lost when the Emacs process is killed.  Because killing
-Emacs inadvertently can lose a lot of work, Emacs queries for
-confirmation before actually terminating if you have buffers that need
-saving or subprocesses that are running.  This is done in the function
address@hidden, the higher level function from which
address@hidden is usually called.
-
address@hidden kill-emacs-query-functions
-After asking the standard questions, @code{save-buffers-kill-emacs}
-calls the functions in the list @code{kill-emacs-query-functions}, in
-order of appearance, with no arguments.  These functions can ask for
-additional confirmation from the user.  If any of them returns
address@hidden, @code{save-buffers-kill-emacs} does not kill Emacs, and
-does not run the remaining functions in this hook.  Calling
address@hidden directly does not run this hook.
address@hidden defvar
-
address@hidden kill-emacs-hook
-This variable is a normal hook; once @code{save-buffers-kill-emacs} is
-finished with all file saving and confirmation, it calls
address@hidden which runs the functions in this hook.
address@hidden does not run this hook in batch mode.
-
address@hidden may be invoked directly (that is not via
address@hidden) if the terminal is disconnected, or in
-similar situations where interaction with the user is not possible.
-Thus, if your hook needs to interact with the user, put it on
address@hidden; if it needs to run regardless of
-how Emacs is killed, put it on @code{kill-emacs-hook}.
address@hidden defvar
-
address@hidden Suspending Emacs
address@hidden Suspending Emacs
address@hidden suspending Emacs
-
-  @dfn{Suspending Emacs} means stopping Emacs temporarily and returning
-control to its superior process, which is usually the shell.  This
-allows you to resume editing later in the same Emacs process, with the
-same buffers, the same kill ring, the same undo history, and so on.  To
-resume Emacs, use the appropriate command in the parent shell---most
-likely @code{fg}.
-
-  Some operating systems do not support suspension of jobs; on these
-systems, ``suspension'' actually creates a new shell temporarily as a
-subprocess of Emacs.  Then you would exit the shell to return to Emacs.
-
-  Suspension is not useful with window systems, because the Emacs job
-may not have a parent that can resume it again, and in any case you can
-give input to some other job such as a shell merely by moving to a
-different window.  Therefore, suspending is not allowed when Emacs is using
-a window system (X, MS Windows, or Mac).
-
address@hidden suspend-emacs &optional string
-This function stops Emacs and returns control to the superior process.
-If and when the superior process resumes Emacs, @code{suspend-emacs}
-returns @code{nil} to its caller in Lisp.
-
-If @var{string} is address@hidden, its characters are sent to be read
-as terminal input by Emacs's superior shell.  The characters in
address@hidden are not echoed by the superior shell; only the results
-appear.
-
-Before suspending, @code{suspend-emacs} runs the normal hook
address@hidden
-
-After the user resumes Emacs, @code{suspend-emacs} runs the normal hook
address@hidden  @xref{Hooks}.
-
-The next redisplay after resumption will redraw the entire screen,
-unless the variable @code{no-redraw-on-reenter} is address@hidden
-(@pxref{Refresh Screen}).
-
-In the following example, note that @samp{pwd} is not echoed after
-Emacs is suspended.  But it is read and executed by the shell.
-
address@hidden
address@hidden
-(suspend-emacs)
-     @result{} nil
address@hidden group
-
address@hidden
-(add-hook 'suspend-hook
-          (function (lambda ()
-                      (or (y-or-n-p
-                            "Really suspend? ")
-                          (error "Suspend canceled")))))
-     @result{} (lambda nil
-          (or (y-or-n-p "Really suspend? ")
-              (error "Suspend canceled")))
address@hidden group
address@hidden
-(add-hook 'suspend-resume-hook
-          (function (lambda () (message "Resumed!"))))
-     @result{} (lambda nil (message "Resumed!"))
address@hidden group
address@hidden
-(suspend-emacs "pwd")
-     @result{} nil
address@hidden group
address@hidden
----------- Buffer: Minibuffer ----------
-Really suspend? @kbd{y}
----------- Buffer: Minibuffer ----------
address@hidden group
-
address@hidden
----------- Parent Shell ----------
-lewis@@slug[23] % /user/lewis/manual
-lewis@@slug[24] % fg
address@hidden group
-
address@hidden
----------- Echo Area ----------
-Resumed!
address@hidden group
address@hidden smallexample
address@hidden defun
-
address@hidden suspend-hook
-This variable is a normal hook that Emacs runs before suspending.
address@hidden defvar
-
address@hidden suspend-resume-hook
-This variable is a normal hook that Emacs runs on resuming
-after a suspension.
address@hidden defvar
-
address@hidden System Environment
address@hidden Operating System Environment
address@hidden operating system environment
-
-  Emacs provides access to variables in the operating system environment
-through various functions.  These variables include the name of the
-system, the user's @acronym{UID}, and so on.
-
address@hidden system-configuration
-This variable holds the standard GNU configuration name for the
-hardware/software configuration of your system, as a string.  The
-convenient way to test parts of this string is with
address@hidden
address@hidden defvar
-
address@hidden system type and name
address@hidden system-type
-The value of this variable is a symbol indicating the type of operating
-system Emacs is operating on.  Here is a table of the possible values:
-
address@hidden @code
address@hidden alpha-vms
-VMS on the Alpha.
-
address@hidden aix-v3
-AIX.
-
address@hidden berkeley-unix
-Berkeley BSD.
-
address@hidden cygwin
-Cygwin.
-
address@hidden dgux
-Data General DGUX operating system.
-
address@hidden gnu
-the GNU system (using the GNU kernel, which consists of the HURD and Mach).
-
address@hidden gnu/linux
-A GNU/Linux system---that is, a variant GNU system, using the Linux
-kernel.  (These systems are the ones people often call ``Linux,'' but
-actually Linux is just the kernel, not the whole system.)
-
address@hidden hpux
-Hewlett-Packard HPUX operating system.
-
address@hidden irix
-Silicon Graphics Irix system.
-
address@hidden ms-dos
-Microsoft MS-DOS ``operating system.''  Emacs compiled with DJGPP for
-MS-DOS binds @code{system-type} to @code{ms-dos} even when you run it on
-MS-Windows.
-
address@hidden next-mach
-NeXT Mach-based system.
-
address@hidden rtu
-Masscomp RTU, UCB universe.
-
address@hidden unisoft-unix
-UniSoft UniPlus.
-
address@hidden usg-unix-v
-AT&T System V.
-
address@hidden vax-vms
-VAX VMS.
-
address@hidden windows-nt
-Microsoft windows NT.  The same executable supports Windows 9X, but the
-value of @code{system-type} is @code{windows-nt} in either case.
-
address@hidden xenix
-SCO Xenix 386.
address@hidden table
-
-We do not wish to add new symbols to make finer distinctions unless it
-is absolutely necessary!  In fact, we hope to eliminate some of these
-alternatives in the future.  We recommend using
address@hidden to distinguish between different operating
-systems.
address@hidden defvar
-
address@hidden system-name
-This function returns the name of the machine you are running on.
address@hidden
-(system-name)
-     @result{} "www.gnu.org"
address@hidden example
address@hidden defun
-
-  The symbol @code{system-name} is a variable as well as a function.  In
-fact, the function returns whatever value the variable
address@hidden currently holds.  Thus, you can set the variable
address@hidden in case Emacs is confused about the name of your
-system.  The variable is also useful for constructing frame titles
-(@pxref{Frame Titles}).
-
address@hidden mail-host-address
-If this variable is address@hidden, it is used instead of
address@hidden for purposes of generating email addresses.  For
-example, it is used when constructing the default value of
address@hidden  @xref{User Identification}.  (Since this is
-done when Emacs starts up, the value actually used is the one saved when
-Emacs was dumped.  @xref{Building Emacs}.)
address@hidden defvar
-
address@hidden Command getenv var
address@hidden environment variable access
-This function returns the value of the environment variable @var{var},
-as a string.  @var{var} should be a string.  If @var{var} is undefined
-in the environment, @code{getenv} returns @code{nil}.  If returns
address@hidden""} if @var{var} is set but null.  Within Emacs, the environment
-variable values are kept in the Lisp variable @code{process-environment}.
-
address@hidden
address@hidden
-(getenv "USER")
-     @result{} "lewis"
address@hidden group
-
address@hidden
-lewis@@slug[10] % printenv
-PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin
-USER=lewis
address@hidden group
address@hidden
-TERM=ibmapa16
-SHELL=/bin/csh
-HOME=/user/lewis
address@hidden group
address@hidden example
address@hidden deffn
-
address@hidden Emacs 19 feature
address@hidden Command setenv variable &optional value
-This command sets the value of the environment variable named
address@hidden to @var{value}.  @var{variable} should be a string.
-Internally, Emacs Lisp can handle any string.  However, normally
address@hidden should be a valid shell identifier, that is, a sequence
-of letters, digits and underscores, starting with a letter or
-underscore.  Otherwise, errors may occur if subprocesses of Emacs try
-to access the value of @var{variable}.  If @var{value} is omitted or
address@hidden, @code{setenv} removes @var{variable} from the environment.
-Otherwise, @var{value} should be a string.
-
address@hidden works by modifying @code{process-environment}; binding
-that variable with @code{let} is also reasonable practice.
-
address@hidden returns the new value of @var{variable}, or @code{nil}
-if it removed @var{variable} from the environment.
address@hidden deffn
-
address@hidden process-environment
-This variable is a list of strings, each describing one environment
-variable.  The functions @code{getenv} and @code{setenv} work by means
-of this variable.
-
address@hidden
address@hidden
-process-environment
address@hidden ("l=/usr/stanford/lib/gnuemacs/lisp"
-    "PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin"
-    "USER=lewis"
address@hidden group
address@hidden
-    "TERM=ibmapa16"
-    "SHELL=/bin/csh"
-    "HOME=/user/lewis")
address@hidden group
address@hidden smallexample
-
-If @code{process-environment} contains ``duplicate'' elements that
-specify the same environment variable, the first of these elements
-specifies the variable, and the other ``duplicates'' are ignored.
address@hidden defvar
-
address@hidden path-separator
-This variable holds a string which says which character separates
-directories in a search path (as found in an environment variable).  Its
-value is @code{":"} for Unix and GNU systems, and @code{";"} for MS-DOS
-and MS-Windows.
address@hidden defvar
-
address@hidden parse-colon-path path
-This function takes a search path string such as would be the value of
-the @code{PATH} environment variable, and splits it at the separators,
-returning a list of directory names.  @code{nil} in this list stands for
-``use the current directory.''  Although the function's name says
-``colon,'' it actually uses the value of @code{path-separator}.
-
address@hidden
-(parse-colon-path ":/foo:/bar")
-     @result{} (nil "/foo/" "/bar/")
address@hidden example
address@hidden defun
-
address@hidden invocation-name
-This variable holds the program name under which Emacs was invoked.  The
-value is a string, and does not include a directory name.
address@hidden defvar
-
address@hidden invocation-directory
-This variable holds the directory from which the Emacs executable was
-invoked, or perhaps @code{nil} if that directory cannot be determined.
address@hidden defvar
-
address@hidden installation-directory
-If address@hidden, this is a directory within which to look for the
address@hidden and @file{etc} subdirectories.  This is address@hidden
-when Emacs can't find those directories in their standard installed
-locations, but can find them in a directory related somehow to the one
-containing the Emacs executable.
address@hidden defvar
-
address@hidden load-average &optional use-float
-This function returns the current 1-minute, 5-minute, and 15-minute load
-averages, in a list.
-
-By default, the values are integers that are 100 times the system load
-averages, which indicate the average number of processes trying to run.
-If @var{use-float} is address@hidden, then they are returned
-as floating point numbers and without multiplying by 100.
-
-If it is impossible to obtain the load average, this function signals
-an error.  On some platforms, access to load averages requires
-installing Emacs as setuid or setgid so that it can read kernel
-information, and that usually isn't advisable.
-
-If the 1-minute load average is available, but the 5- or 15-minute
-averages are not, this function returns a shortened list containing
-the available averages.
-
address@hidden
address@hidden
-(load-average)
-     @result{} (169 48 36)
address@hidden group
address@hidden
-(load-average t)
-     @result{} (1.69 0.48 0.36)
address@hidden group
-
address@hidden
-lewis@@rocky[5] % uptime
- 11:55am  up 1 day, 19:37,  3 users,
- load average: 1.69, 0.48, 0.36
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden emacs-pid
-This function returns the process @acronym{ID} of the Emacs process,
-as an integer.
address@hidden defun
-
address@hidden tty-erase-char
-This variable holds the erase character that was selected
-in the system's terminal driver, before Emacs was started.
-The value is @code{nil} if Emacs is running under a window system.
address@hidden defvar
-
address@hidden setprv privilege-name &optional setp getprv
-This function sets or resets a VMS privilege.  (It does not exist on
-other systems.)  The first argument is the privilege name, as a string.
-The second argument, @var{setp}, is @code{t} or @code{nil}, indicating
-whether the privilege is to be turned on or off.  Its default is
address@hidden  The function returns @code{t} if successful, @code{nil}
-otherwise.
-
-If the third argument, @var{getprv}, is address@hidden, @code{setprv}
-does not change the privilege, but returns @code{t} or @code{nil}
-indicating whether the privilege is currently enabled.
address@hidden defun
-
address@hidden User Identification
address@hidden User Identification
address@hidden user identification
-
address@hidden init-file-user
-This variable says which user's init files should be used by
-Emacs---or @code{nil} if none.  @code{""} stands for the user who
-originally logged in.  The value reflects command-line options such as
address@hidden or @samp{-u @var{user}}.
-
-Lisp packages that load files of customizations, or any other sort of
-user profile, should obey this variable in deciding where to find it.
-They should load the profile of the user name found in this variable.
-If @code{init-file-user} is @code{nil}, meaning that the @samp{-q}
-option was used, then Lisp packages should not load any customization
-files or user profile.
address@hidden defvar
-
address@hidden user-mail-address
-This holds the nominal email address of the user who is using Emacs.
-Emacs normally sets this variable to a default value after reading your
-init files, but not if you have already set it.  So you can set the
-variable to some other value in your init file if you do not
-want to use the default value.
address@hidden defvar
-
address@hidden user-login-name &optional uid
-If you don't specify @var{uid}, this function returns the name under
-which the user is logged in.  If the environment variable @code{LOGNAME}
-is set, that value is used.  Otherwise, if the environment variable
address@hidden is set, that value is used.  Otherwise, the value is based
-on the effective @acronym{UID}, not the real @acronym{UID}.
-
-If you specify @var{uid}, the value is the user name that corresponds
-to @var{uid} (which should be an integer), or @code{nil} if there is
-no such user.
-
address@hidden
address@hidden
-(user-login-name)
-     @result{} "lewis"
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden user-real-login-name
-This function returns the user name corresponding to Emacs's real
address@hidden  This ignores the effective @acronym{UID} and ignores the
-environment variables @code{LOGNAME} and @code{USER}.
address@hidden defun
-
address@hidden user-full-name &optional uid
-This function returns the full name of the logged-in user---or the value
-of the environment variable @code{NAME}, if that is set.
-
address@hidden "Bil" is the correct spelling.
address@hidden
address@hidden
-(user-full-name)
-     @result{} "Bil Lewis"
address@hidden group
address@hidden example
-
-If the Emacs job's user-id does not correspond to any known user (and
-provided @code{NAME} is not set), the value is @code{"unknown"}.
-
-If @var{uid} is address@hidden, then it should be a number (a user-id)
-or a string (a login name).  Then @code{user-full-name} returns the full
-name corresponding to that user-id or login name.  If you specify a
-user-id or login name that isn't defined, it returns @code{nil}.
address@hidden defun
-
address@hidden user-full-name
address@hidden user-real-login-name
address@hidden user-login-name
-  The symbols @code{user-login-name}, @code{user-real-login-name} and
address@hidden are variables as well as functions.  The functions
-return the same values that the variables hold.  These variables allow
-you to ``fake out'' Emacs by telling the functions what to return.  The
-variables are also useful for constructing frame titles (@pxref{Frame
-Titles}).
-
address@hidden user-real-uid
-This function returns the real @acronym{UID} of the user.
-The value may be a floating point number.
-
address@hidden
address@hidden
-(user-real-uid)
-     @result{} 19
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden user-uid
-This function returns the effective @acronym{UID} of the user.
-The value may be a floating point number.
address@hidden defun
-
address@hidden Time of Day
address@hidden Time of Day
-
-  This section explains how to determine the current time and the time
-zone.
-
address@hidden current-time-string &optional time-value
-This function returns the current time and date as a human-readable
-string.  The format of the string is unvarying; the number of characters
-used for each part is always the same, so you can reliably use
address@hidden to extract pieces of it.  It is wise to count the
-characters from the beginning of the string rather than from the end, as
-additional information may some day be added at the end.
-
address@hidden Emacs 19 feature
-The argument @var{time-value}, if given, specifies a time to format
-instead of the current time.  The argument should be a list whose first
-two elements are integers.  Thus, you can use times obtained from
address@hidden (see below) and from @code{file-attributes}
-(@pxref{Definition of file-attributes}).  @var{time-value} can also be
-a cons of two integers, but this is considered obsolete.
-
address@hidden
address@hidden
-(current-time-string)
-     @result{} "Wed Oct 14 22:21:05 1987"
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden Emacs 19 feature
address@hidden current-time
-This function returns the system's time value as a list of three
-integers: @code{(@var{high} @var{low} @var{microsec})}.  The integers
address@hidden and @var{low} combine to give the number of seconds since
-0:00 January 1, 1970 UTC (Coordinated Universal Time), which is
address@hidden
address@hidden * 2**16 + @var{low}.
address@hidden ifnottex
address@hidden
-$high*2^{16}+low$.
address@hidden tex
-
-The third element, @var{microsec}, gives the microseconds since the
-start of the current second (or 0 for systems that return time with
-the resolution of only one second).
-
-The first two elements can be compared with file time values such as you
-get with the function @code{file-attributes}.
address@hidden of file-attributes}.
address@hidden defun
-
address@hidden Emacs 19 feature
address@hidden current-time-zone &optional time-value
-This function returns a list describing the time zone that the user is
-in.
-
-The value has the form @code{(@var{offset} @var{name})}.  Here
address@hidden is an integer giving the number of seconds ahead of UTC
-(east of Greenwich).  A negative value means west of Greenwich.  The
-second element, @var{name}, is a string giving the name of the time
-zone.  Both elements change when daylight saving time begins or ends;
-if the user has specified a time zone that does not use a seasonal time
-adjustment, then the value is constant through time.
-
-If the operating system doesn't supply all the information necessary to
-compute the value, the unknown elements of the list are @code{nil}.
-
-The argument @var{time-value}, if given, specifies a time to analyze
-instead of the current time.  The argument should have the same form
-as for @code{current-time-string} (see above).  Thus, you can use
-times obtained from @code{current-time} (see above) and from
address@hidden  @xref{Definition of file-attributes}.
address@hidden defun
-
address@hidden set-time-zone-rule tz
-This function specifies the local time zone according to @var{tz}.  If
address@hidden is @code{nil}, that means to use an implementation-defined
-default time zone.  If @var{tz} is @code{t}, that means to use
-Universal Time.  Otherwise, @var{tz} should be a string specifying a
-time zone rule.
address@hidden defun
-
address@hidden float-time &optional time-value
-This function returns the current time as a floating-point number of
-seconds since the epoch.  The argument @var{time-value}, if given,
-specifies a time to convert instead of the current time.  The argument
-should have the same form as for @code{current-time-string} (see
-above).  Thus, it accepts the output of @code{current-time} and
address@hidden
-
address@hidden: Since the result is floating point, it may not be
-exact.  Do not use this function if precise time stamps are required.
address@hidden defun
-
address@hidden Time Conversion
address@hidden Time Conversion
-
-  These functions convert time values (lists of two or three integers)
-to calendrical information and vice versa.  You can get time values
-from the functions @code{current-time} (@pxref{Time of Day}) and
address@hidden (@pxref{Definition of file-attributes}).
-
-  Many operating systems are limited to time values that contain 32 bits
-of information; these systems typically handle only the times from
-1901-12-13 20:45:52 UTC through 2038-01-19 03:14:07 UTC.  However, some
-operating systems have larger time values, and can represent times far
-in the past or future.
-
-  Time conversion functions always use the Gregorian calendar, even
-for dates before the Gregorian calendar was introduced.  Year numbers
-count the number of years since the year 1 B.C., and do not skip zero
-as traditional Gregorian years do; for example, the year number
address@hidden represents the Gregorian year 38 address@hidden
-
address@hidden decode-time &optional time
-This function converts a time value into calendrical information.  If
-you don't specify @var{time}, it decodes the current time.  The return
-value is a list of nine elements, as follows:
-
address@hidden
-(@var{seconds} @var{minutes} @var{hour} @var{day} @var{month} @var{year} 
@var{dow} @var{dst} @var{zone})
address@hidden example
-
-Here is what the elements mean:
-
address@hidden @var
address@hidden seconds
-The number of seconds past the minute, as an integer between 0 and 59.
-On some operating systems, this is 60 for leap seconds.
address@hidden minutes
-The number of minutes past the hour, as an integer between 0 and 59.
address@hidden hour
-The hour of the day, as an integer between 0 and 23.
address@hidden day
-The day of the month, as an integer between 1 and 31.
address@hidden month
-The month of the year, as an integer between 1 and 12.
address@hidden year
-The year, an integer typically greater than 1900.
address@hidden dow
-The day of week, as an integer between 0 and 6, where 0 stands for
-Sunday.
address@hidden dst
address@hidden if daylight saving time is effect, otherwise @code{nil}.
address@hidden zone
-An integer indicating the time zone, as the number of seconds east of
-Greenwich.
address@hidden table
-
address@hidden Lisp Note:} Common Lisp has different meanings for
address@hidden and @var{zone}.
address@hidden defun
-
address@hidden encode-time seconds minutes hour day month year &optional zone
-This function is the inverse of @code{decode-time}.  It converts seven
-items of calendrical data into a time value.  For the meanings of the
-arguments, see the table above under @code{decode-time}.
-
-Year numbers less than 100 are not treated specially.  If you want them
-to stand for years above 1900, or years above 2000, you must alter them
-yourself before you call @code{encode-time}.
-
-The optional argument @var{zone} defaults to the current time zone and
-its daylight saving time rules.  If specified, it can be either a list
-(as you would get from @code{current-time-zone}), a string as in the
address@hidden environment variable, @code{t} for Universal Time, or an
-integer (as you would get from @code{decode-time}).  The specified
-zone is used without any further alteration for daylight saving time.
-
-If you pass more than seven arguments to @code{encode-time}, the first
-six are used as @var{seconds} through @var{year}, the last argument is
-used as @var{zone}, and the arguments in between are ignored.  This
-feature makes it possible to use the elements of a list returned by
address@hidden as the arguments to @code{encode-time}, like this:
-
address@hidden
-(apply 'encode-time (decode-time @dots{}))
address@hidden example
-
-You can perform simple date arithmetic by using out-of-range values for
-the @var{seconds}, @var{minutes}, @var{hour}, @var{day}, and @var{month}
-arguments; for example, day 0 means the day preceding the given month.
-
-The operating system puts limits on the range of possible time values;
-if you try to encode a time that is out of range, an error results.
-For instance, years before 1970 do not work on some systems;
-on others, years as early as 1901 do work.
address@hidden defun
-
address@hidden Time Parsing
address@hidden Parsing and Formatting Times
-
-  These functions convert time values (lists of two or three integers)
-to text in a string, and vice versa.
-
address@hidden date-to-time string
-This function parses the time-string @var{string} and returns the
-corresponding time value.
address@hidden defun
-
address@hidden format-time-string format-string &optional time universal
-This function converts @var{time} (or the current time, if @var{time} is
-omitted) to a string according to @var{format-string}.  The argument
address@hidden may contain @samp{%}-sequences which say to
-substitute parts of the time.  Here is a table of what the
address@hidden mean:
-
address@hidden @samp
address@hidden %a
-This stands for the abbreviated name of the day of week.
address@hidden %A
-This stands for the full name of the day of week.
address@hidden %b
-This stands for the abbreviated name of the month.
address@hidden %B
-This stands for the full name of the month.
address@hidden %c
-This is a synonym for @samp{%x %X}.
address@hidden %C
-This has a locale-specific meaning.  In the default locale (named C), it
-is equivalent to @samp{%A, %B %e, %Y}.
address@hidden %d
-This stands for the day of month, zero-padded.
address@hidden %D
-This is a synonym for @samp{%m/%d/%y}.
address@hidden %e
-This stands for the day of month, blank-padded.
address@hidden %h
-This is a synonym for @samp{%b}.
address@hidden %H
-This stands for the hour (00-23).
address@hidden %I
-This stands for the hour (01-12).
address@hidden %j
-This stands for the day of the year (001-366).
address@hidden %k
-This stands for the hour (0-23), blank padded.
address@hidden %l
-This stands for the hour (1-12), blank padded.
address@hidden %m
-This stands for the month (01-12).
address@hidden %M
-This stands for the minute (00-59).
address@hidden %n
-This stands for a newline.
address@hidden %p
-This stands for @samp{AM} or @samp{PM}, as appropriate.
address@hidden %r
-This is a synonym for @samp{%I:%M:%S %p}.
address@hidden %R
-This is a synonym for @samp{%H:%M}.
address@hidden %S
-This stands for the seconds (00-59).
address@hidden %t
-This stands for a tab character.
address@hidden %T
-This is a synonym for @samp{%H:%M:%S}.
address@hidden %U
-This stands for the week of the year (01-52), assuming that weeks
-start on Sunday.
address@hidden %w
-This stands for the numeric day of week (0-6).  Sunday is day 0.
address@hidden %W
-This stands for the week of the year (01-52), assuming that weeks
-start on Monday.
address@hidden %x
-This has a locale-specific meaning.  In the default locale (named
address@hidden), it is equivalent to @samp{%D}.
address@hidden %X
-This has a locale-specific meaning.  In the default locale (named
address@hidden), it is equivalent to @samp{%T}.
address@hidden %y
-This stands for the year without century (00-99).
address@hidden %Y
-This stands for the year with century.
address@hidden %Z
-This stands for the time zone abbreviation (e.g., @samp{EST}).
address@hidden %z
-This stands for the time zone numerical offset (e.g., @samp{-0500}).
address@hidden table
-
-You can also specify the field width and type of padding for any of
-these @samp{%}-sequences.  This works as in @code{printf}: you write
-the field width as digits in the middle of a @samp{%}-sequences.  If you
-start the field width with @samp{0}, it means to pad with zeros.  If you
-start the field width with @samp{_}, it means to pad with spaces.
-
-For example, @samp{%S} specifies the number of seconds since the minute;
address@hidden means to pad this with zeros to 3 positions, @samp{%_3S} to
-pad with spaces to 3 positions.  Plain @samp{%3S} pads with zeros,
-because that is how @samp{%S} normally pads to two positions.
-
-The characters @samp{E} and @samp{O} act as modifiers when used between
address@hidden and one of the letters in the table above.  @samp{E} specifies
-using the current locale's ``alternative'' version of the date and time.
-In a Japanese locale, for example, @code{%Ex} might yield a date format
-based on the Japanese Emperors' reigns.  @samp{E} is allowed in
address@hidden, @samp{%EC}, @samp{%Ex}, @samp{%EX}, @samp{%Ey}, and
address@hidden
-
address@hidden means to use the current locale's ``alternative''
-representation of numbers, instead of the ordinary decimal digits.  This
-is allowed with most letters, all the ones that output numbers.
-
-If @var{universal} is address@hidden, that means to describe the time as
-Universal Time; @code{nil} means describe it using what Emacs believes
-is the local time zone (see @code{current-time-zone}).
-
-This function uses the C library function @code{strftime}
-(@pxref{Formatting Calendar Time,,, libc, The GNU C Library Reference
-Manual}) to do most of the work.  In order to communicate with that
-function, it first encodes its argument using the coding system
-specified by @code{locale-coding-system} (@pxref{Locales}); after
address@hidden returns the resulting string,
address@hidden decodes the string using that same coding
-system.
address@hidden defun
-
address@hidden seconds-to-time seconds
-This function converts @var{seconds}, a floating point number of
-seconds since the epoch, to a time value and returns that.  To perform
-the inverse conversion, use @code{float-time}.
address@hidden defun
-
address@hidden Processor Run Time
address@hidden Processor Run time
address@hidden processor run time
-
address@hidden get-internal-run-time
-This function returns the processor run time used by Emacs as a list
-of three integers: @code{(@var{high} @var{low} @var{microsec})}.  The
-integers @var{high} and @var{low} combine to give the number of
-seconds, which is
address@hidden
address@hidden * 2**16 + @var{low}.
address@hidden ifnottex
address@hidden
-$high*2^{16}+low$.
address@hidden tex
-
-The third element, @var{microsec}, gives the microseconds (or 0 for
-systems that return time with the resolution of only one second).
-
-If the system doesn't provide a way to determine the processor run
-time, get-internal-run-time returns the same time as current-time.
address@hidden defun
-
address@hidden Time Calculations
address@hidden Time Calculations
-
-  These functions perform calendrical computations using time values
-(the kind of list that @code{current-time} returns).
-
address@hidden time-less-p t1 t2
-This returns @code{t} if time value @var{t1} is less than time value
address@hidden
address@hidden defun
-
address@hidden time-subtract t1 t2
-This returns the time difference @var{t1} @minus{} @var{t2} between
-two time values, in the same format as a time value.
address@hidden defun
-
address@hidden time-add t1 t2
-This returns the sum of two time values, one of which ought to
-represent a time difference rather than a point in time.
-Here is how to add a number of seconds to a time value:
-
address@hidden
-(time-add @var{time} (seconds-to-time @var{seconds}))
address@hidden example
address@hidden defun
-
address@hidden time-to-days time
-This function returns the number of days between the beginning of year
-1 and @var{time}.
address@hidden defun
-
address@hidden time-to-day-in-year time
-This returns the day number within the year corresponding to @var{time}.
address@hidden defun
-
address@hidden date-leap-year-p year
-This function returns @code{t} if @var{year} is a leap year.
address@hidden defun
-
address@hidden Timers
address@hidden Timers for Delayed Execution
address@hidden timer
-
-  You can set up a @dfn{timer} to call a function at a specified
-future time or after a certain length of idleness.
-
-  Emacs cannot run timers at any arbitrary point in a Lisp program; it
-can run them only when Emacs could accept output from a subprocess:
-namely, while waiting or inside certain primitive functions such as
address@hidden or @code{read-event} which @emph{can} wait.  Therefore, a
-timer's execution may be delayed if Emacs is busy.  However, the time of
-execution is very precise if Emacs is idle.
-
-  Emacs binds @code{inhibit-quit} to @code{t} before calling the timer
-function, because quitting out of many timer functions can leave
-things in an inconsistent state.  This is normally unproblematical
-because most timer functions don't do a lot of work.  Indeed, for a
-timer to call a function that takes substantial time to run is likely
-to be annoying.  If a timer function needs to allow quitting, it
-should use @code{with-local-quit} (@pxref{Quitting}).  For example, if
-a timer function calls @code{accept-process-output} to receive output
-from an external process, that call should be wrapped inside
address@hidden, to ensure that @kbd{C-g} works if the external
-process hangs.
-
-  It is usually a bad idea for timer functions to alter buffer
-contents.  When they do, they usually should call @code{undo-boundary}
-both before and after changing the buffer, to separate the timer's
-changes from user commands' changes and prevent a single undo entry
-from growing to be quite large.
-
-  Timer functions should also avoid calling functions that cause Emacs
-to wait, such as @code{sit-for} (@pxref{Waiting}).  This can lead to
-unpredictable effects, since other timers (or even the same timer) can
-run while waiting.  If a timer function needs to perform an action
-after a certain time has elapsed, it can do this by scheduling a new
-timer.
-
-  If a timer function calls functions that can change the match data,
-it should save and restore the match data.  @xref{Saving Match Data}.
-
address@hidden Command run-at-time time repeat function &rest args
-This sets up a timer that calls the function @var{function} with
-arguments @var{args} at time @var{time}.  If @var{repeat} is a number
-(integer or floating point), the timer is scheduled to run again every
address@hidden seconds after @var{time}.  If @var{repeat} is @code{nil},
-the timer runs only once.
-
address@hidden may specify an absolute or a relative time.
-
-Absolute times may be specified using a string with a limited variety
-of formats, and are taken to be times @emph{today}, even if already in
-the past.  The recognized forms are @address@hidden,
address@hidden@var{x}:@var{xx}}, or @address@hidden:@var{xx}} (military time),
-and @address@hidden, @address@hidden, @address@hidden,
address@hidden@var{xx}PM}, @address@hidden:@var{xx}am},
address@hidden@var{xx}:@var{xx}AM}, @address@hidden:@var{xx}pm}, or
address@hidden@var{xx}:@var{xx}PM}.  A period can be used instead of a colon
-to separate the hour and minute parts.
-
-To specify a relative time as a string, use numbers followed by units.
-For example:
-
address@hidden @samp
address@hidden 1 min
-denotes 1 minute from now.
address@hidden 1 min 5 sec
-denotes 65 seconds from now.
address@hidden 1 min 2 sec 3 hour 4 day 5 week 6 fortnight 7 month 8 year
-denotes exactly 103 months, 123 days, and 10862 seconds from now.
address@hidden table
-
-For relative time values, Emacs considers a month to be exactly thirty
-days, and a year to be exactly 365.25 days.
-
-Not all convenient formats are strings.  If @var{time} is a number
-(integer or floating point), that specifies a relative time measured in
-seconds.  The result of @code{encode-time} can also be used to specify
-an absolute value for @var{time}.
-
-In most cases, @var{repeat} has no effect on when @emph{first} call
-takes address@hidden alone specifies that.  There is one exception:
-if @var{time} is @code{t}, then the timer runs whenever the time is a
-multiple of @var{repeat} seconds after the epoch.  This is useful for
-functions like @code{display-time}.
-
-The function @code{run-at-time} returns a timer value that identifies
-the particular scheduled future action.  You can use this value to call
address@hidden (see below).
address@hidden deffn
-
-  A repeating timer nominally ought to run every @var{repeat} seconds,
-but remember that any invocation of a timer can be late.  Lateness of
-one repetition has no effect on the scheduled time of the next
-repetition.  For instance, if Emacs is busy computing for long enough
-to cover three scheduled repetitions of the timer, and then starts to
-wait, it will immediately call the timer function three times in
-immediate succession (presuming no other timers trigger before or
-between them).  If you want a timer to run again no less than @var{n}
-seconds after the last invocation, don't use the @var{repeat} argument.
-Instead, the timer function should explicitly reschedule the timer.
-
address@hidden timer-max-repeats
-This variable's value specifies the maximum number of times to repeat
-calling a timer function in a row, when many previously scheduled
-calls were unavoidably delayed.
address@hidden defvar
-
address@hidden with-timeout (seconds address@hidden) address@hidden
-Execute @var{body}, but give up after @var{seconds} seconds.  If
address@hidden finishes before the time is up, @code{with-timeout} returns
-the value of the last form in @var{body}.  If, however, the execution of
address@hidden is cut short by the timeout, then @code{with-timeout}
-executes all the @var{timeout-forms} and returns the value of the last
-of them.
-
-This macro works by setting a timer to run after @var{seconds} seconds.  If
address@hidden finishes before that time, it cancels the timer.  If the
-timer actually runs, it terminates execution of @var{body}, then
-executes @var{timeout-forms}.
-
-Since timers can run within a Lisp program only when the program calls a
-primitive that can wait, @code{with-timeout} cannot stop executing
address@hidden while it is in the midst of a computation---only when it
-calls one of those primitives.  So use @code{with-timeout} only with a
address@hidden that waits for input, not one that does a long computation.
address@hidden defmac
-
-  The function @code{y-or-n-p-with-timeout} provides a simple way to use
-a timer to avoid waiting too long for an answer.  @xref{Yes-or-No
-Queries}.
-
address@hidden cancel-timer timer
-This cancels the requested action for @var{timer}, which should be a
-timer---usually, one previously returned by @code{run-at-time} or
address@hidden  This cancels the effect of that call to
-one of these functions; the arrival of the specified time will not
-cause anything special to happen.
address@hidden defun
-
address@hidden Idle Timers
address@hidden Idle Timers
-
-  Here is how to set up a timer that runs when Emacs is idle for a
-certain length of time.  Aside from how to set them up, idle timers
-work just like ordinary timers.
-
address@hidden Command run-with-idle-timer secs repeat function &rest args
-Set up a timer which runs when Emacs has been idle for @var{secs}
-seconds.  The value of @var{secs} may be an integer or a floating point
-number; a value of the type returned by @code{current-idle-time}
-is also allowed.
-
-If @var{repeat} is @code{nil}, the timer runs just once, the first time
-Emacs remains idle for a long enough time.  More often @var{repeat} is
address@hidden, which means to run the timer @emph{each time} Emacs
-remains idle for @var{secs} seconds.
-
-The function @code{run-with-idle-timer} returns a timer value which you
-can use in calling @code{cancel-timer} (@pxref{Timers}).
address@hidden deffn
-
address@hidden idleness
-  Emacs becomes ``idle'' when it starts waiting for user input, and it
-remains idle until the user provides some input.  If a timer is set for
-five seconds of idleness, it runs approximately five seconds after Emacs
-first becomes idle.  Even if @var{repeat} is address@hidden, this timer
-will not run again as long as Emacs remains idle, because the duration
-of idleness will continue to increase and will not go down to five
-seconds again.
-
-  Emacs can do various things while idle: garbage collect, autosave or
-handle data from a subprocess.  But these interludes during idleness do
-not interfere with idle timers, because they do not reset the clock of
-idleness to zero.  An idle timer set for 600 seconds will run when ten
-minutes have elapsed since the last user command was finished, even if
-subprocess output has been accepted thousands of times within those ten
-minutes, and even if there have been garbage collections and autosaves.
-
-  When the user supplies input, Emacs becomes non-idle while executing the
-input.  Then it becomes idle again, and all the idle timers that are
-set up to repeat will subsequently run another time, one by one.
-
address@hidden Emacs 19 feature
address@hidden current-idle-time
-This function returns the length of time Emacs has been idle, as a
-list of three integers: @code{(@var{high} @var{low} @var{microsec})}.
-The integers @var{high} and @var{low} combine to give the number of
-seconds of idleness, which is
address@hidden
address@hidden * 2**16 + @var{low}.
address@hidden ifnottex
address@hidden
-$high*2^{16}+low$.
address@hidden tex
-
-The third element, @var{microsec}, gives the microseconds since the
-start of the current second (or 0 for systems that return time with
-the resolution of only one second).
-
-The main use of this function is when an idle timer function wants to
-``take a break'' for a while.  It can set up another idle timer to
-call the same function again, after a few seconds more idleness.
-Here's an example:
-
address@hidden
-(defvar resume-timer nil
-  "Timer that `timer-function' used to reschedule itself, or nil.")
-
-(defun timer-function ()
-  ;; @r{If the user types a command while @code{resume-timer}}
-  ;; @r{is active, the next time this function is called from}
-  ;; @r{its main idle timer, deactivate @code{resume-timer}.}
-  (when resume-timer
-    (cancel-timer resume-timer))
-  address@hidden the work for a while}...
-  (when @var{taking-a-break}
-    (setq resume-timer
-          (run-with-idle-timer
-            ;; Compute an idle time @var{break-length}
-            ;; more than the current value.
-            (time-add (current-idle-time)
-                      (seconds-to-time @var{break-length}))
-            nil
-            'timer-function))))
address@hidden smallexample
address@hidden defun
-
-  Some idle timer functions in user Lisp packages have a loop that
-does a certain amount of processing each time around, and exits when
address@hidden(input-pending-p)} is address@hidden  That approach seems very
-natural but has two problems:
-
address@hidden
address@hidden
-It blocks out all process output (since Emacs accepts process output
-only while waiting).
-
address@hidden
-It blocks out any idle timers that ought to run during that time.
address@hidden itemize
-
address@hidden
-To avoid these problems, don't use that technique.  Instead, write
-such idle timers to reschedule themselves after a brief pause, using
-the method in the @code{timer-function} example above.
-
address@hidden Terminal Input
address@hidden Terminal Input
address@hidden terminal input
-
-  This section describes functions and variables for recording or
-manipulating terminal input.  See @ref{Display}, for related
-functions.
-
address@hidden
-* Input Modes::                Options for how input is processed.
-* Recording Input::    Saving histories of recent or all input events.
address@hidden menu
-
address@hidden Input Modes
address@hidden Input Modes
address@hidden input modes
address@hidden terminal input modes
-
address@hidden set-input-mode interrupt flow meta &optional quit-char
-This function sets the mode for reading keyboard input.  If
address@hidden is non-null, then Emacs uses input interrupts.  If it is
address@hidden, then it uses @sc{cbreak} mode.  The default setting is
-system-dependent.  Some systems always use @sc{cbreak} mode regardless
-of what is specified.
-
-When Emacs communicates directly with X, it ignores this argument and
-uses interrupts if that is the way it knows how to communicate.
-
-If @var{flow} is address@hidden, then Emacs uses @sc{xon/xoff}
-(@kbd{C-q}, @kbd{C-s}) flow control for output to the terminal.  This
-has no effect except in @sc{cbreak} mode.
-
address@hidden Emacs 19 feature
-The argument @var{meta} controls support for input character codes
-above 127.  If @var{meta} is @code{t}, Emacs converts characters with
-the 8th bit set into Meta characters.  If @var{meta} is @code{nil},
-Emacs disregards the 8th bit; this is necessary when the terminal uses
-it as a parity bit.  If @var{meta} is neither @code{t} nor @code{nil},
-Emacs uses all 8 bits of input unchanged.  This is good for terminals
-that use 8-bit character sets.
-
address@hidden Emacs 19 feature
-If @var{quit-char} is address@hidden, it specifies the character to
-use for quitting.  Normally this character is @kbd{C-g}.
address@hidden
address@hidden defun
-
-The @code{current-input-mode} function returns the input mode settings
-Emacs is currently using.
-
address@hidden Emacs 19 feature
address@hidden current-input-mode
-This function returns the current mode for reading keyboard input.  It
-returns a list, corresponding to the arguments of @code{set-input-mode},
-of the form @code{(@var{interrupt} @var{flow} @var{meta} @var{quit})} in
-which:
address@hidden @var
address@hidden interrupt
-is address@hidden when Emacs is using interrupt-driven input.  If
address@hidden, Emacs is using @sc{cbreak} mode.
address@hidden flow
-is address@hidden if Emacs uses @sc{xon/xoff} (@kbd{C-q}, @kbd{C-s})
-flow control for output to the terminal.  This value is meaningful only
-when @var{interrupt} is @code{nil}.
address@hidden meta
-is @code{t} if Emacs treats the eighth bit of input characters as
-the meta bit; @code{nil} means Emacs clears the eighth bit of every
-input character; any other value means Emacs uses all eight bits as the
-basic character code.
address@hidden quit
-is the character Emacs currently uses for quitting, usually @kbd{C-g}.
address@hidden table
address@hidden defun
-
address@hidden Recording Input
address@hidden Recording Input
address@hidden recording input
-
address@hidden recent-keys
-This function returns a vector containing the last 300 input events from
-the keyboard or mouse.  All input events are included, whether or not
-they were used as parts of key sequences.  Thus, you always get the last
-100 input events, not counting events generated by keyboard macros.
-(These are excluded because they are less interesting for debugging; it
-should be enough to see the events that invoked the macros.)
-
-A call to @code{clear-this-command-keys} (@pxref{Command Loop Info})
-causes this function to return an empty vector immediately afterward.
address@hidden defun
-
address@hidden Command open-dribble-file filename
address@hidden dribble file
-This function opens a @dfn{dribble file} named @var{filename}.  When a
-dribble file is open, each input event from the keyboard or mouse (but
-not those from keyboard macros) is written in that file.  A
-non-character event is expressed using its printed representation
-surrounded by @samp{<@dots{}>}.
-
-You close the dribble file by calling this function with an argument
-of @code{nil}.
-
-This function is normally used to record the input necessary to
-trigger an Emacs bug, for the sake of a bug report.
-
address@hidden
address@hidden
-(open-dribble-file "~/dribble")
-     @result{} nil
address@hidden group
address@hidden example
address@hidden deffn
-
-  See also the @code{open-termscript} function (@pxref{Terminal Output}).
-
address@hidden Terminal Output
address@hidden Terminal Output
address@hidden terminal output
-
-  The terminal output functions send output to a text terminal, or keep
-track of output sent to the terminal.  The variable @code{baud-rate}
-tells you what Emacs thinks is the output speed of the terminal.
-
address@hidden baud-rate
-This variable's value is the output speed of the terminal, as far as
-Emacs knows.  Setting this variable does not change the speed of actual
-data transmission, but the value is used for calculations such as
-padding.
-
-  It also affects decisions about whether to scroll part of the
-screen or repaint on text terminals.  @xref{Forcing Redisplay},
-for the corresponding functionality on graphical terminals.
-
-The value is measured in baud.
address@hidden defvar
-
-  If you are running across a network, and different parts of the
-network work at different baud rates, the value returned by Emacs may be
-different from the value used by your local terminal.  Some network
-protocols communicate the local terminal speed to the remote machine, so
-that Emacs and other programs can get the proper value, but others do
-not.  If Emacs has the wrong value, it makes decisions that are less
-than optimal.  To fix the problem, set @code{baud-rate}.
-
address@hidden baud-rate
-This obsolete function returns the value of the variable
address@hidden
address@hidden defun
-
address@hidden send-string-to-terminal string
-This function sends @var{string} to the terminal without alteration.
-Control characters in @var{string} have terminal-dependent effects.
-This function operates only on text terminals.
-
-One use of this function is to define function keys on terminals that
-have downloadable function key definitions.  For example, this is how (on
-certain terminals) to define function key 4 to move forward four
-characters (by transmitting the characters @kbd{C-u C-f} to the
-computer):
-
address@hidden
address@hidden
-(send-string-to-terminal "\eF4\^U\^F")
-     @result{} nil
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden Command open-termscript filename
address@hidden termscript file
-This function is used to open a @dfn{termscript file} that will record
-all the characters sent by Emacs to the terminal.  It returns
address@hidden  Termscript files are useful for investigating problems
-where Emacs garbles the screen, problems that are due to incorrect
-Termcap entries or to undesirable settings of terminal options more
-often than to actual Emacs bugs.  Once you are certain which characters
-were actually output, you can determine reliably whether they correspond
-to the Termcap specifications in use.
-
-You close the termscript file by calling this function with an
-argument of @code{nil}.
-
-See also @code{open-dribble-file} in @ref{Recording Input}.
-
address@hidden
address@hidden
-(open-termscript "../junk/termscript")
-     @result{} nil
address@hidden group
address@hidden example
address@hidden deffn
-
address@hidden Sound Output
address@hidden Sound Output
address@hidden sound
-
-  To play sound using Emacs, use the function @code{play-sound}.  Only
-certain systems are supported; if you call @code{play-sound} on a system
-which cannot really do the job, it gives an error.  Emacs version 20 and
-earlier did not support sound at all.
-
-  The sound must be stored as a file in RIFF-WAVE format (@samp{.wav})
-or Sun Audio format (@samp{.au}).
-
address@hidden play-sound sound
-This function plays a specified sound.  The argument, @var{sound}, has
-the form @code{(sound @var{properties}...)}, where the @var{properties}
-consist of alternating keywords (particular symbols recognized
-specially) and values corresponding to them.
-
-Here is a table of the keywords that are currently meaningful in
address@hidden, and their meanings:
-
address@hidden @code
address@hidden :file @var{file}
-This specifies the file containing the sound to play.
-If the file name is not absolute, it is expanded against
-the directory @code{data-directory}.
-
address@hidden :data @var{data}
-This specifies the sound to play without need to refer to a file.  The
-value, @var{data}, should be a string containing the same bytes as a
-sound file.  We recommend using a unibyte string.
-
address@hidden :volume @var{volume}
-This specifies how loud to play the sound.  It should be a number in the
-range of 0 to 1.  The default is to use whatever volume has been
-specified before.
-
address@hidden :device @var{device}
-This specifies the system device on which to play the sound, as a
-string.  The default device is system-dependent.
address@hidden table
-
-Before actually playing the sound, @code{play-sound}
-calls the functions in the list @code{play-sound-functions}.
-Each function is called with one argument, @var{sound}.
address@hidden defun
-
address@hidden play-sound-file file &optional volume device
-This function is an alternative interface to playing a sound @var{file}
-specifying an optional @var{volume} and @var{device}.
address@hidden defun
-
address@hidden play-sound-functions
-A list of functions to be called before playing a sound.  Each function
-is called with one argument, a property list that describes the sound.
address@hidden defvar
-
address@hidden X11 Keysyms
address@hidden Operating on X11 Keysyms
address@hidden X11 keysyms
-
-To define system-specific X11 keysyms, set the variable
address@hidden
-
address@hidden system-key-alist
-This variable's value should be an alist with one element for each
-system-specific keysym.  Each element has the form @code{(@var{code}
-. @var{symbol})}, where @var{code} is the numeric keysym code (not
-including the ``vendor specific'' bit,
address@hidden
--2**28),
address@hidden ifnottex
address@hidden
-$-2^{28}$),
address@hidden tex
-and @var{symbol} is the name for the function key.
-
-For example @code{(168 . mute-acute)} defines a system-specific key (used
-by HP X servers) whose numeric code is
address@hidden
--2**28
address@hidden ifnottex
address@hidden
-$-2^{28}$
address@hidden tex
-+ 168.
-
-It is not crucial to exclude from the alist the keysyms of other X
-servers; those do no harm, as long as they don't conflict with the ones
-used by the X server actually in use.
-
-The variable is always local to the current terminal, and cannot be
-buffer-local.  @xref{Multiple Displays}.
address@hidden defvar
-
-You can specify which keysyms Emacs should use for the Meta, Alt, Hyper, and 
Super modifiers by setting these variables:
-
address@hidden x-alt-keysym
address@hidden x-meta-keysym
address@hidden x-hyper-keysym
address@hidden x-super-keysym
-The name of the keysym that should stand for the Alt modifier
-(respectively, for Meta, Hyper, and Super).  For example, here is
-how to swap the Meta and Alt modifiers within Emacs:
address@hidden
-(setq x-alt-keysym 'meta)
-(setq x-meta-keysym 'alt)
address@hidden lisp
address@hidden defvar
-
address@hidden Batch Mode
address@hidden Batch Mode
address@hidden batch mode
-
-  The command-line option @samp{-batch} causes Emacs to run
-noninteractively.  In this mode, Emacs does not read commands from the
-terminal, it does not alter the terminal modes, and it does not expect
-to be outputting to an erasable screen.  The idea is that you specify
-Lisp programs to run; when they are finished, Emacs should exit.  The
-way to specify the programs to run is with @samp{-l @var{file}}, which
-loads the library named @var{file}, or @samp{-f @var{function}}, which
-calls @var{function} with no arguments, or @samp{--eval @var{form}}.
-
-  Any Lisp program output that would normally go to the echo area,
-either using @code{message}, or using @code{prin1}, etc., with @code{t}
-as the stream, goes instead to Emacs's standard error descriptor when
-in batch mode.  Similarly, input that would normally come from the
-minibuffer is read from the standard input descriptor.
-Thus, Emacs behaves much like a noninteractive
-application program.  (The echo area output that Emacs itself normally
-generates, such as command echoing, is suppressed entirely.)
-
address@hidden noninteractive
-This variable is address@hidden when Emacs is running in batch mode.
address@hidden defvar
-
address@hidden Session Management
address@hidden Session Management
address@hidden session manager
-
-Emacs supports the X Session Management Protocol for suspension and
-restart of applications.  In the X Window System, a program called the
address@hidden manager} has the responsibility to keep track of the
-applications that are running.  During shutdown, the session manager
-asks applications to save their state, and delays the actual shutdown
-until they respond.  An application can also cancel the shutdown.
-
-When the session manager restarts a suspended session, it directs
-these applications to individually reload their saved state.  It does
-this by specifying a special command-line argument that says what
-saved session to restore.  For Emacs, this argument is @samp{--smid
address@hidden
-
address@hidden emacs-save-session-functions
-Emacs supports saving state by using a hook called
address@hidden  Each function in this hook is
-called when the session manager tells Emacs that the window system is
-shutting down.  The functions are called with no arguments and with the
-current buffer set to a temporary buffer.  Each function can use
address@hidden to add Lisp code to this buffer.  At the end, Emacs
-saves the buffer in a file that a subsequent Emacs invocation will
-load in order to restart the saved session.
-
-If a function in @code{emacs-save-session-functions} returns
address@hidden, Emacs tells the session manager to cancel the
-shutdown.
address@hidden defvar
-
-Here is an example that just inserts some text into @samp{*scratch*} when
-Emacs is restarted by the session manager.
-
address@hidden
address@hidden
-(add-hook 'emacs-save-session-functions 'save-yourself-test)
address@hidden group
-
address@hidden
-(defun save-yourself-test ()
-  (insert "(save-excursion
-  (switch-to-buffer \"*scratch*\")
-  (insert \"I am restored\"))")
-  nil)
address@hidden group
address@hidden example
-
address@hidden
-   arch-tag: 8378814a-30d7-467c-9615-74a80b9988a7
address@hidden ignore




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