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1787 lines
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1787 lines
64 KiB
Plaintext
@c -*-texinfo-*-
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@c This is part of the GNU Emacs Lisp Reference Manual.
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@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@setfilename ../info/os
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@node System Interface, Tips, Calendar, Top
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@chapter Operating System Interface
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This chapter is about starting and getting out of Emacs, access to
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values in the operating system environment, and terminal input, output,
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and flow control.
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@xref{Building Emacs}, for related information. See also
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@ref{Display}, for additional operating system status information
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pertaining to the terminal and the screen.
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@menu
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* Starting Up:: Customizing Emacs start-up processing.
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* Getting Out:: How exiting works (permanent or temporary).
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* System Environment:: Distinguish the name and kind of system.
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* User Identification:: Finding the name and user id of the user.
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* Time of Day:: Getting the current time.
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* Time Conversion:: Converting a time from numeric form to a string, or
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to calendrical data (or vice versa).
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* Timers:: Setting a timer to call a function at a certain time.
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* Terminal Input:: Recording terminal input for debugging.
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* Terminal Output:: Recording terminal output for debugging.
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* Special Keysyms:: Defining system-specific key symbols for X windows.
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* Flow Control:: How to turn output flow control on or off.
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* Batch Mode:: Running Emacs without terminal interaction.
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@end menu
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@node Starting Up
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@section Starting Up Emacs
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This section describes what Emacs does when it is started, and how you
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can customize these actions.
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@menu
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* Start-up Summary:: Sequence of actions Emacs performs at start-up.
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* Init File:: Details on reading the init file (@file{.emacs}).
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* Terminal-Specific:: How the terminal-specific Lisp file is read.
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* Command Line Arguments:: How command line arguments are processed,
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and how you can customize them.
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@end menu
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@node Start-up Summary
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@subsection Summary: Sequence of Actions at Start Up
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@cindex initialization
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@cindex start up of Emacs
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@cindex @file{startup.el}
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The order of operations performed (in @file{startup.el}) by Emacs when
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it is started up is as follows:
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@enumerate
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@item
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It adds subdirectories to @code{load-path}, by running the file
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named @file{subdirs.el} in each directory that is listed.
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@item
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It sets the language environment and the terminal coding system,
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if requested by environment variables such as @code{LANG}.
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@item
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It loads the initialization library for the window system, if you are
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using a window system. This library's name is
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@file{term/@var{windowsystem}-win.el}.
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@item
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It processes the initial options. (Some of them are handled
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even earlier than this.)
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@item
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It initializes the window frame and faces, if appropriate.
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@item
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It runs the normal hook @code{before-init-hook}.
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@item
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It loads the library @file{site-start}, unless the option
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@samp{-no-site-file} was specified. The library's file name is usually
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@file{site-start.el}.
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@cindex @file{site-start.el}
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@item
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It loads the file @file{~/.emacs}, unless @samp{-q} or @samp{-batch} was
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specified on the command line. The @samp{-u} option can specify another
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user name whose home directory should be used instead of @file{~}.
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@item
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It loads the library @file{default}, unless @code{inhibit-default-init}
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is non-@code{nil}. (This is not done in @samp{-batch} mode or if
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@samp{-q} was specified on the command line.) The library's file name
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is usually @file{default.el}.
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@cindex @file{default.el}
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@item
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It runs the normal hook @code{after-init-hook}.
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@item
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It sets the major mode according to @code{initial-major-mode}, provided
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the buffer @samp{*scratch*} is still current and still in Fundamental
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mode.
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@item
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It loads the terminal-specific Lisp file, if any, except when in batch
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mode or using a window system.
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@item
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It displays the initial echo area message, unless you have suppressed
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that with @code{inhibit-startup-echo-area-message}.
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@item
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It processes the action arguments from the command line.
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@item
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It runs @code{term-setup-hook}.
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@item
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It calls @code{frame-notice-user-settings}, which modifies the
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parameters of the selected frame according to whatever the init files
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specify.
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@item
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It runs @code{window-setup-hook}. @xref{Window Systems}.
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@item
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It displays copyleft, nonwarranty, and basic use information, provided
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there were no remaining command line arguments (a few steps above),
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the value of @code{inhibit-startup-message} is @code{nil}, and the
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buffer is still empty.
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@end enumerate
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@defopt inhibit-startup-message
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This variable inhibits the initial startup messages (the nonwarranty,
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etc.). If it is non-@code{nil}, then the messages are not printed.
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This variable exists so you can set it in your personal init file, once
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you are familiar with the contents of the startup message. Do not set
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this variable in the init file of a new user, or in a way that affects
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more than one user, because that would prevent new users from receiving
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the information they are supposed to see.
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@end defopt
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@defopt inhibit-startup-echo-area-message
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This variable controls the display of the startup echo area message.
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You can suppress the startup echo area message by adding text with this
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form to your @file{.emacs} file:
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@example
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(setq inhibit-startup-echo-area-message
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"@var{your-login-name}")
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@end example
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Emacs explicitly checks for an expression as shown above in your
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@file{.emacs} file; your login name must appear in the expression as a
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Lisp string constant. Other methods of setting
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@code{inhibit-startup-echo-area-message} to the same value do not
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inhibit the startup message.
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This way, you can easily inhibit the message for yourself if you wish,
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but thoughtless copying of your @file{.emacs} file will not inhibit the
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message for someone else.
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@end defopt
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@node Init File
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@subsection The Init File: @file{.emacs}
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@cindex init file
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@cindex @file{.emacs}
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When you start Emacs, it normally attempts to load the file
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@file{.emacs} from your home directory. This file, if it exists, must
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contain Lisp code. It is called your @dfn{init file}. The command line
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switches @samp{-q} and @samp{-u} affect the use of the init file;
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@samp{-q} says not to load an init file, and @samp{-u} says to load a
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specified user's init file instead of yours. @xref{Entering Emacs,,,
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emacs, The GNU Emacs Manual}.
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@cindex default init file
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A site may have a @dfn{default init file}, which is the library named
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@file{default.el}. Emacs finds the @file{default.el} file through the
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standard search path for libraries (@pxref{How Programs Do Loading}).
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The Emacs distribution does not come with this file; sites may provide
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one for local customizations. If the default init file exists, it is
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loaded whenever you start Emacs, except in batch mode or if @samp{-q} is
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specified. But your own personal init file, if any, is loaded first; if
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it sets @code{inhibit-default-init} to a non-@code{nil} value, then
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Emacs does not subsequently load the @file{default.el} file.
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Another file for site-customization is @file{site-start.el}. Emacs
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loads this @emph{before} the user's init file. You can inhibit the
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loading of this file with the option @samp{-no-site-file}.
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@defvar site-run-file
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This variable specifies the site-customization file to load before the
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user's init file. Its normal value is @code{"site-start"}. The only
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way you can change it with real effect is to do so before dumping
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Emacs.
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@end defvar
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If there is a great deal of code in your @file{.emacs} file, you
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should move it into another file named @file{@var{something}.el},
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byte-compile it (@pxref{Byte Compilation}), and make your @file{.emacs}
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file load the other file using @code{load} (@pxref{Loading}).
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@xref{Init File Examples,,, emacs, The GNU Emacs Manual}, for
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examples of how to make various commonly desired customizations in your
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@file{.emacs} file.
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@defopt inhibit-default-init
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This variable prevents Emacs from loading the default initialization
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library file for your session of Emacs. If its value is non-@code{nil},
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then the default library is not loaded. The default value is
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@code{nil}.
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@end defopt
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@defvar before-init-hook
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This normal hook is run, once, just before loading all the init files
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(the user's init file, @file{default.el}, and/or @file{site-start.el}).
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(The only way to change it with real effect is before dumping Emacs.)
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@end defvar
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@defvar after-init-hook
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This normal hook is run, once, just after loading all the init files
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(the user's init file, @file{default.el}, and/or @file{site-start.el}),
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before the terminal-specific initialization.
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@end defvar
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@node Terminal-Specific
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@subsection Terminal-Specific Initialization
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@cindex terminal-specific initialization
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Each terminal type can have its own Lisp library that Emacs loads when
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run on that type of terminal. The library's name is constructed by
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concatenating the value of the variable @code{term-file-prefix} and the
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terminal type. Normally, @code{term-file-prefix} has the value
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@code{"term/"}; changing this is not recommended. Emacs finds the file
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in the normal manner, by searching the @code{load-path} directories, and
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trying the @samp{.elc} and @samp{.el} suffixes.
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The usual function of a terminal-specific library is to enable special
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keys to send sequences that Emacs can recognize. It may also need to
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set or add to @code{function-key-map} if the Termcap entry does not
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specify all the terminal's function keys. @xref{Terminal Input}.
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@cindex Termcap
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When the name of the terminal type contains a hyphen, only the part of
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the name before the first hyphen is significant in choosing the library
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name. Thus, terminal types @samp{aaa-48} and @samp{aaa-30-rv} both use
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the @file{term/aaa} library. If necessary, the library can evaluate
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@code{(getenv "TERM")} to find the full name of the terminal
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type.@refill
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Your @file{.emacs} file can prevent the loading of the
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terminal-specific library by setting the variable
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@code{term-file-prefix} to @code{nil}. This feature is useful when
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experimenting with your own peculiar customizations.
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You can also arrange to override some of the actions of the
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terminal-specific library by setting the variable
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@code{term-setup-hook}. This is a normal hook which Emacs runs using
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@code{run-hooks} at the end of Emacs initialization, after loading both
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your @file{.emacs} file and any terminal-specific libraries. You can
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use this variable to define initializations for terminals that do not
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have their own libraries. @xref{Hooks}.
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@defvar term-file-prefix
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@cindex @code{TERM} environment variable
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If the @code{term-file-prefix} variable is non-@code{nil}, Emacs loads
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a terminal-specific initialization file as follows:
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@example
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(load (concat term-file-prefix (getenv "TERM")))
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@end example
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@noindent
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You may set the @code{term-file-prefix} variable to @code{nil} in your
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@file{.emacs} file if you do not wish to load the
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terminal-initialization file. To do this, put the following in
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your @file{.emacs} file: @code{(setq term-file-prefix nil)}.
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@end defvar
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@defvar term-setup-hook
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This variable is a normal hook that Emacs runs after loading your
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@file{.emacs} file, the default initialization file (if any) and the
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terminal-specific Lisp file.
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You can use @code{term-setup-hook} to override the definitions made by a
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terminal-specific file.
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@end defvar
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See @code{window-setup-hook} in @ref{Window Systems}, for a related
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feature.
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@node Command Line Arguments
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@subsection Command Line Arguments
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@cindex command line arguments
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You can use command line arguments to request various actions when you
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start Emacs. Since you do not need to start Emacs more than once per
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day, and will often leave your Emacs session running longer than that,
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command line arguments are hardly ever used. As a practical matter, it
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is best to avoid making the habit of using them, since this habit would
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encourage you to kill and restart Emacs unnecessarily often. These
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options exist for two reasons: to be compatible with other editors (for
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invocation by other programs) and to enable shell scripts to run
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specific Lisp programs.
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This section describes how Emacs processes command line arguments,
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and how you can customize them.
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@ignore
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(Note that some other editors require you to start afresh each time
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you want to edit a file. With this kind of editor, you will probably
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specify the file as a command line argument. The recommended way to
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use GNU Emacs is to start it only once, just after you log in, and do
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all your editing in the same Emacs process. Each time you want to edit
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a different file, you visit it with the existing Emacs, which eventually
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comes to have many files in it ready for editing. Usually you do not
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kill the Emacs until you are about to log out.)
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@end ignore
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@defun command-line
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This function parses the command line that Emacs was called with,
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processes it, loads the user's @file{.emacs} file and displays the
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startup messages.
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@end defun
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@defvar command-line-processed
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The value of this variable is @code{t} once the command line has been
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processed.
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If you redump Emacs by calling @code{dump-emacs}, you may wish to set
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this variable to @code{nil} first in order to cause the new dumped Emacs
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to process its new command line arguments.
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@end defvar
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@defvar command-switch-alist
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@cindex switches on command line
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@cindex options on command line
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@cindex command line options
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The value of this variable is an alist of user-defined command-line
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options and associated handler functions. This variable exists so you
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can add elements to it.
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A @dfn{command line option} is an argument on the command line of the
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form:
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@example
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-@var{option}
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@end example
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The elements of the @code{command-switch-alist} look like this:
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@example
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(@var{option} . @var{handler-function})
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@end example
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The @var{handler-function} is called to handle @var{option} and receives
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the option name as its sole argument.
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In some cases, the option is followed in the command line by an
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argument. In these cases, the @var{handler-function} can find all the
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remaining command-line arguments in the variable
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@code{command-line-args-left}. (The entire list of command-line
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arguments is in @code{command-line-args}.)
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The command line arguments are parsed by the @code{command-line-1}
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function in the @file{startup.el} file. See also @ref{Command
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Switches, , Command Line Switches and Arguments, emacs, The GNU Emacs
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Manual}.
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@end defvar
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@defvar command-line-args
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The value of this variable is the list of command line arguments passed
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to Emacs.
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@end defvar
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@defvar command-line-functions
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This variable's value is a list of functions for handling an
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unrecognized command-line argument. Each time the next argument to be
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processed has no special meaning, the functions in this list are called,
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in order of appearance, until one of them returns a non-@code{nil}
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value.
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These functions are called with no arguments. They can access the
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command-line argument under consideration through the variable
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@code{argi}, which is bound temporarily at this point. The remaining
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arguments (not including the current one) are in the variable
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@code{command-line-args-left}.
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When a function recognizes and processes the argument in @code{argi}, it
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should return a non-@code{nil} value to say it has dealt with that
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argument. If it has also dealt with some of the following arguments, it
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can indicate that by deleting them from @code{command-line-args-left}.
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If all of these functions return @code{nil}, then the argument is used
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as a file name to visit.
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@end defvar
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@node Getting Out
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@section Getting Out of Emacs
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@cindex exiting Emacs
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There are two ways to get out of Emacs: you can kill the Emacs job,
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which exits permanently, or you can suspend it, which permits you to
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reenter the Emacs process later. As a practical matter, you seldom kill
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Emacs---only when you are about to log out. Suspending is much more
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common.
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@menu
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* Killing Emacs:: Exiting Emacs irreversibly.
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* Suspending Emacs:: Exiting Emacs reversibly.
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@end menu
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@node Killing Emacs
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@comment node-name, next, previous, up
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@subsection Killing Emacs
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@cindex killing Emacs
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Killing Emacs means ending the execution of the Emacs process. The
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parent process normally resumes control. The low-level primitive for
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killing Emacs is @code{kill-emacs}.
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@defun kill-emacs &optional exit-data
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This function exits the Emacs process and kills it.
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If @var{exit-data} is an integer, then it is used as the exit status
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of the Emacs process. (This is useful primarily in batch operation; see
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@ref{Batch Mode}.)
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If @var{exit-data} is a string, its contents are stuffed into the
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terminal input buffer so that the shell (or whatever program next reads
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input) can read them.
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@end defun
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All the information in the Emacs process, aside from files that have
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been saved, is lost when the Emacs is killed. Because killing Emacs
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inadvertently can lose a lot of work, Emacs queries for confirmation
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before actually terminating if you have buffers that need saving or
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subprocesses that are running. This is done in the function
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@code{save-buffers-kill-emacs}.
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@defvar kill-emacs-query-functions
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After asking the standard questions, @code{save-buffers-kill-emacs}
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calls the functions in the list @code{kill-emacs-query-functions}, in
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order of appearance, with no arguments. These functions can ask for
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additional confirmation from the user. If any of them returns
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@code{nil}, Emacs is not killed.
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@end defvar
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@defvar kill-emacs-hook
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This variable is a normal hook; once @code{save-buffers-kill-emacs} is
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finished with all file saving and confirmation, it runs the functions in
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this hook.
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@end defvar
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@node Suspending Emacs
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@subsection Suspending Emacs
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@cindex suspending Emacs
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@dfn{Suspending Emacs} means stopping Emacs temporarily and returning
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control to its superior process, which is usually the shell. This
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allows you to resume editing later in the same Emacs process, with the
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same buffers, the same kill ring, the same undo history, and so on. To
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resume Emacs, use the appropriate command in the parent shell---most
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likely @code{fg}.
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Some operating systems do not support suspension of jobs; on these
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systems, ``suspension'' actually creates a new shell temporarily as a
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subprocess of Emacs. Then you would exit the shell to return to Emacs.
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Suspension is not useful with window systems, because the Emacs job
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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.
|
|
|
|
@defun suspend-emacs 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 non-@code{nil}, its characters are sent to be read
|
|
as terminal input by Emacs's superior shell. The characters in
|
|
@var{string} are not echoed by the superior shell; only the results
|
|
appear.
|
|
|
|
Before suspending, @code{suspend-emacs} runs the normal hook
|
|
@code{suspend-hook}.
|
|
|
|
After the user resumes Emacs, @code{suspend-emacs} runs the normal hook
|
|
@code{suspend-resume-hook}. @xref{Hooks}.
|
|
|
|
The next redisplay after resumption will redraw the entire screen,
|
|
unless the variable @code{no-redraw-on-reenter} is non-@code{nil}
|
|
(@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.
|
|
|
|
@smallexample
|
|
@group
|
|
(suspend-emacs)
|
|
@result{} nil
|
|
@end group
|
|
|
|
@group
|
|
(add-hook 'suspend-hook
|
|
(function (lambda ()
|
|
(or (y-or-n-p
|
|
"Really suspend? ")
|
|
(error "Suspend cancelled")))))
|
|
@result{} (lambda nil
|
|
(or (y-or-n-p "Really suspend? ")
|
|
(error "Suspend cancelled")))
|
|
@end group
|
|
@group
|
|
(add-hook 'suspend-resume-hook
|
|
(function (lambda () (message "Resumed!"))))
|
|
@result{} (lambda nil (message "Resumed!"))
|
|
@end group
|
|
@group
|
|
(suspend-emacs "pwd")
|
|
@result{} nil
|
|
@end group
|
|
@group
|
|
---------- Buffer: Minibuffer ----------
|
|
Really suspend? @kbd{y}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
|
|
@group
|
|
---------- Parent Shell ----------
|
|
lewis@@slug[23] % /user/lewis/manual
|
|
lewis@@slug[24] % fg
|
|
@end group
|
|
|
|
@group
|
|
---------- Echo Area ----------
|
|
Resumed!
|
|
@end group
|
|
@end smallexample
|
|
@end defun
|
|
|
|
@defvar suspend-hook
|
|
This variable is a normal hook run before suspending.
|
|
@end defvar
|
|
|
|
@defvar suspend-resume-hook
|
|
This variable is a normal hook run after suspending.
|
|
@end defvar
|
|
|
|
@node System Environment
|
|
@section Operating System Environment
|
|
@cindex 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 @sc{uid}, and so on.
|
|
|
|
@defvar system-configuration
|
|
This variable holds the 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 @code{string-match}.
|
|
@end defvar
|
|
|
|
@defvar 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:
|
|
|
|
@table @code
|
|
@item alpha-vms
|
|
VMS on the Alpha.
|
|
|
|
@item aix-v3
|
|
AIX.
|
|
|
|
@item berkeley-unix
|
|
Berkeley BSD.
|
|
|
|
@item dgux
|
|
Data General DGUX operating system.
|
|
|
|
@item gnu
|
|
the GNU system (using the GNU kernel, which consists of the HURD and Mach).
|
|
|
|
@item 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.)
|
|
|
|
@item hpux
|
|
Hewlett-Packard HPUX operating system.
|
|
|
|
@item irix
|
|
Silicon Graphics Irix system.
|
|
|
|
@item ms-dos
|
|
Microsoft MS-DOS ``operating system.''
|
|
|
|
@item next-mach
|
|
NeXT Mach-based system.
|
|
|
|
@item rtu
|
|
Masscomp RTU, UCB universe.
|
|
|
|
@item unisoft-unix
|
|
UniSoft UniPlus.
|
|
|
|
@item usg-unix-v
|
|
AT&T System V.
|
|
|
|
@item vax-vms
|
|
VAX VMS.
|
|
|
|
@item windows-nt
|
|
Microsoft windows NT.
|
|
|
|
@item xenix
|
|
SCO Xenix 386.
|
|
@end 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
|
|
@code{system-configuration} to distinguish between different operating
|
|
systems.
|
|
@end defvar
|
|
|
|
@defun system-name
|
|
This function returns the name of the machine you are running on.
|
|
@example
|
|
(system-name)
|
|
@result{} "www.gnu.org"
|
|
@end example
|
|
@end defun
|
|
|
|
The symbol @code{system-name} is a variable as well as a function. In
|
|
fact, the function returns whatever value the variable
|
|
@code{system-name} currently holds. Thus, you can set the variable
|
|
@code{system-name} in case Emacs is confused about the name of your
|
|
system. The variable is also useful for constructing frame titles
|
|
(@pxref{Frame Titles}).
|
|
|
|
@defvar mail-host-address
|
|
If this variable is non-@code{nil}, it is used instead of
|
|
@code{system-name} for purposes of generating email addresses. For
|
|
example, it is used when constructing the default value of
|
|
@code{user-mail-address}. @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}.)
|
|
@end defvar
|
|
|
|
@defun getenv var
|
|
@cindex environment variable access
|
|
This function returns the value of the environment variable @var{var},
|
|
as a string. Within Emacs, the environment variable values are kept in
|
|
the Lisp variable @code{process-environment}.
|
|
|
|
@example
|
|
@group
|
|
(getenv "USER")
|
|
@result{} "lewis"
|
|
@end group
|
|
|
|
@group
|
|
lewis@@slug[10] % printenv
|
|
PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin
|
|
USER=lewis
|
|
@end group
|
|
@group
|
|
TERM=ibmapa16
|
|
SHELL=/bin/csh
|
|
HOME=/user/lewis
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@c Emacs 19 feature
|
|
@deffn Command setenv variable value
|
|
This command sets the value of the environment variable named
|
|
@var{variable} to @var{value}. Both arguments should be strings. This
|
|
function works by modifying @code{process-environment}; binding that
|
|
variable with @code{let} is also reasonable practice.
|
|
@end deffn
|
|
|
|
@defvar 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.
|
|
|
|
@smallexample
|
|
@group
|
|
process-environment
|
|
@result{} ("l=/usr/stanford/lib/gnuemacs/lisp"
|
|
"PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin"
|
|
"USER=lewis"
|
|
@end group
|
|
@group
|
|
"TERM=ibmapa16"
|
|
"SHELL=/bin/csh"
|
|
"HOME=/user/lewis")
|
|
@end group
|
|
@end smallexample
|
|
@end defvar
|
|
|
|
@defvar 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 Windows NT.
|
|
@end defvar
|
|
|
|
@defvar 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.
|
|
@end defvar
|
|
|
|
@defvar invocation-directory
|
|
This variable holds the directory from which the Emacs executable was
|
|
invoked, or perhaps @code{nil} if that directory cannot be determined.
|
|
@end defvar
|
|
|
|
@defvar installation-directory
|
|
If non-@code{nil}, this is a directory within which to look for the
|
|
@file{lib-src} and @file{etc} subdirectories. This is non-@code{nil}
|
|
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.
|
|
@end defvar
|
|
|
|
@defun 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 non-@code{nil}, then they are returned
|
|
as floating point numbers and without multiplying by 100.
|
|
|
|
@example
|
|
@group
|
|
(load-average)
|
|
@result{} (169 48 36)
|
|
@end group
|
|
@group
|
|
(load-average t)
|
|
@result{} (1.69 0.48 0.36)
|
|
@end group
|
|
|
|
@group
|
|
lewis@@rocky[5] % uptime
|
|
11:55am up 1 day, 19:37, 3 users,
|
|
load average: 1.69, 0.48, 0.36
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun emacs-pid
|
|
This function returns the process @sc{id} of the Emacs process.
|
|
@end defun
|
|
|
|
@defvar tty-erase-char
|
|
@tindex tty-erase-char
|
|
This variable holds the erase character that was selected
|
|
in the system's terminal driver, before Emacs was started.
|
|
@end defvar
|
|
|
|
@defun setprv privilege-name &optional setp getprv
|
|
This function sets or resets a VMS privilege. (It does not exist on
|
|
Unix.) The first arg 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 @code{nil}. The
|
|
function returns @code{t} if successful, @code{nil} otherwise.
|
|
|
|
If the third argument, @var{getprv}, is non-@code{nil}, @code{setprv}
|
|
does not change the privilege, but returns @code{t} or @code{nil}
|
|
indicating whether the privilege is currently enabled.
|
|
@end defun
|
|
|
|
@node User Identification
|
|
@section User Identification
|
|
|
|
@defvar init-file-user
|
|
This variable says which user's init files should be used by Emacs---or
|
|
@code{nil} if none. The value reflects command line options such as
|
|
@samp{-q} 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.
|
|
@end defvar
|
|
|
|
@defvar 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 @file{~/.emacs} file if you do not
|
|
want to use the default value.
|
|
@end defvar
|
|
|
|
@defun 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
|
|
@code{USER} is set, that value is used. Otherwise, the value is based
|
|
on the effective @sc{uid}, not the real @sc{uid}.
|
|
|
|
If you specify @var{uid}, the value is the user name that corresponds
|
|
to @var{uid} (which should be an integer).
|
|
|
|
@example
|
|
@group
|
|
(user-login-name)
|
|
@result{} "lewis"
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun user-real-login-name
|
|
This function returns the user name corresponding to Emacs's real
|
|
@sc{uid}. This ignores the effective @sc{uid} and ignores the
|
|
environment variables @code{LOGNAME} and @code{USER}.
|
|
@end defun
|
|
|
|
@defun user-full-name &optional uid
|
|
This function returns the full name of the logged-in user---or the value
|
|
of the environment variables @code{NAME}, if that is set.
|
|
|
|
@example
|
|
@group
|
|
(user-full-name)
|
|
@result{} "Bil Lewis"
|
|
@end group
|
|
@end example
|
|
|
|
If @var{uid} is non-@code{nil}, then it should be an integer, 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.
|
|
@end defun
|
|
|
|
@vindex user-full-name
|
|
@vindex user-real-login-name
|
|
@vindex user-login-name
|
|
The symbols @code{user-login-name}, @code{user-real-login-name} and
|
|
@code{user-full-name} 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}).
|
|
|
|
@defun user-real-uid
|
|
This function returns the real @sc{uid} of the user.
|
|
|
|
@example
|
|
@group
|
|
(user-real-uid)
|
|
@result{} 19
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun user-uid
|
|
This function returns the effective @sc{uid} of the user.
|
|
@end defun
|
|
|
|
@node Time of Day
|
|
@section Time of Day
|
|
|
|
This section explains how to determine the current time and the time
|
|
zone.
|
|
|
|
@defun 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
|
|
@code{substring} 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.
|
|
|
|
@c 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
|
|
@code{current-time} (see below) and from @code{file-attributes}
|
|
(@pxref{File Attributes}).
|
|
|
|
@example
|
|
@group
|
|
(current-time-string)
|
|
@result{} "Wed Oct 14 22:21:05 1987"
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@c Emacs 19 feature
|
|
@defun 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
|
|
@var{high} and @var{low} combine to give the number of seconds since
|
|
0:00 January 1, 1970, which is
|
|
@ifinfo
|
|
@var{high} * 2**16 + @var{low}.
|
|
@end ifinfo
|
|
@tex
|
|
$high*2^{16}+low$.
|
|
@end tex
|
|
|
|
The third element, @var{microsec}, gives the microseconds since the
|
|
start of the current second (or 0 for systems that return time only on
|
|
the resolution of a second).
|
|
|
|
The first two elements can be compared with file time values such as you
|
|
get with the function @code{file-attributes}. @xref{File Attributes}.
|
|
@end defun
|
|
|
|
@c Emacs 19 feature
|
|
@defun 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
|
|
@var{offset} 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 savings 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, both 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 be a cons cell
|
|
containing two integers, or a list whose first two elements are
|
|
integers. Thus, you can use times obtained from @code{current-time}
|
|
(see above) and from @code{file-attributes} (@pxref{File Attributes}).
|
|
@end defun
|
|
|
|
@node Time Conversion
|
|
@section Time Conversion
|
|
|
|
These functions convert time values (lists of two or three integers)
|
|
to strings or to calendrical information. There is also a function to
|
|
convert calendrical information to a time value. You can get time
|
|
values from the functions @code{current-time} (@pxref{Time of Day}) and
|
|
@code{file-attributes} (@pxref{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 @minus{}37
|
|
represents the Gregorian year 38 B.C@.
|
|
|
|
@defun format-time-string format-string time
|
|
This function converts @var{time} to a string according to
|
|
@var{format-string}. The argument @var{format-string} may contain
|
|
@samp{%}-sequences which say to substitute parts of the time. Here is a
|
|
table of what the @samp{%}-sequences mean:
|
|
|
|
@table @samp
|
|
@item %a
|
|
This stands for the abbreviated name of the day of week.
|
|
@item %A
|
|
This stands for the full name of the day of week.
|
|
@item %b
|
|
This stands for the abbreviated name of the month.
|
|
@item %B
|
|
This stands for the full name of the month.
|
|
@item %c
|
|
This is a synonym for @samp{%x %X}.
|
|
@item %C
|
|
This has a locale-specific meaning. In the default locale (named C), it
|
|
is equivalent to @samp{%A, %B %e, %Y}.
|
|
@item %d
|
|
This stands for the day of month, zero-padded.
|
|
@item %D
|
|
This is a synonym for @samp{%m/%d/%y}.
|
|
@item %e
|
|
This stands for the day of month, blank-padded.
|
|
@item %h
|
|
This is a synonym for @samp{%b}.
|
|
@item %H
|
|
This stands for the hour (00-23).
|
|
@item %I
|
|
This stands for the hour (00-12).
|
|
@item %j
|
|
This stands for the day of the year (001-366).
|
|
@item %k
|
|
This stands for the hour (0-23), blank padded.
|
|
@item %l
|
|
This stands for the hour (1-12), blank padded.
|
|
@item %m
|
|
This stands for the month (01-12).
|
|
@item %M
|
|
This stands for the minute (00-59).
|
|
@item %n
|
|
This stands for a newline.
|
|
@item %p
|
|
This stands for @samp{AM} or @samp{PM}, as appropriate.
|
|
@item %r
|
|
This is a synonym for @samp{%I:%M:%S %p}.
|
|
@item %R
|
|
This is a synonym for @samp{%H:%M}.
|
|
@item %S
|
|
This stands for the seconds (00-60).
|
|
@item %t
|
|
This stands for a tab character.
|
|
@item %T
|
|
This is a synonym for @samp{%H:%M:%S}.
|
|
@item %U
|
|
This stands for the week of the year (01-52), assuming that weeks
|
|
start on Sunday.
|
|
@item %w
|
|
This stands for the numeric day of week (0-6). Sunday is day 0.
|
|
@item %W
|
|
This stands for the week of the year (01-52), assuming that weeks
|
|
start on Monday.
|
|
@item %x
|
|
This has a locale-specific meaning. In the default locale (named
|
|
@samp{C}), it is equivalent to @samp{%D}.
|
|
@item %X
|
|
This has a locale-specific meaning. In the default locale (named
|
|
@samp{C}), it is equivalent to @samp{%T}.
|
|
@item %y
|
|
This stands for the year without century (00-99).
|
|
@item %Y
|
|
This stands for the year with century.
|
|
@item %Z
|
|
This stands for the time zone abbreviation.
|
|
@end 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;
|
|
@samp{%03S} 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.
|
|
@end defun
|
|
|
|
@defun decode-time time
|
|
This function converts a time value into calendrical information. The
|
|
return value is a list of nine elements, as follows:
|
|
|
|
@example
|
|
(@var{seconds} @var{minutes} @var{hour} @var{day} @var{month} @var{year} @var{dow} @var{dst} @var{zone})
|
|
@end example
|
|
|
|
Here is what the elements mean:
|
|
|
|
@table @var
|
|
@item sec
|
|
The number of seconds past the minute, as an integer between 0 and 59.
|
|
@item minute
|
|
The number of minutes past the hour, as an integer between 0 and 59.
|
|
@item hour
|
|
The hour of the day, as an integer between 0 and 23.
|
|
@item day
|
|
The day of the month, as an integer between 1 and 31.
|
|
@item month
|
|
The month of the year, as an integer between 1 and 12.
|
|
@item year
|
|
The year, an integer typically greater than 1900.
|
|
@item dow
|
|
The day of week, as an integer between 0 and 6, where 0 stands for
|
|
Sunday.
|
|
@item dst
|
|
@code{t} if daylight savings time is effect, otherwise @code{nil}.
|
|
@item zone
|
|
An integer indicating the time zone, as the number of seconds east of
|
|
Greenwich.
|
|
@end table
|
|
|
|
@strong{Common Lisp Note:} Common Lisp has different meanings for
|
|
@var{dow} and @var{zone}.
|
|
@end defun
|
|
|
|
@defun encode-time seconds minutes hour day month year &optional @dots{}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 treated just like other year numbers. If
|
|
you want them to stand for years above 1900, 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 savings time rules. If specified, it can be either a list
|
|
(as you would get from @code{current-time-zone}), a string as in the
|
|
@code{TZ} environment variable, or an integer (as you would get from
|
|
@code{decode-time}). The specified zone is used without any further
|
|
alteration for daylight savings 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
|
|
@code{decode-time} as the arguments to @code{encode-time}, like this:
|
|
|
|
@example
|
|
(apply 'encode-time (decode-time @dots{}))
|
|
@end example
|
|
|
|
You can perform simple date arithmetic by using out-of-range values for
|
|
the @var{sec}, @var{minute}, @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.
|
|
@end defun
|
|
|
|
@node Timers
|
|
@section Timers for Delayed Execution
|
|
@cindex 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
|
|
@code{sit-for} 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.
|
|
|
|
@defun run-at-time time repeat function &rest args
|
|
This function arranges to call @var{function} with arguments @var{args}
|
|
at time @var{time}. The argument @var{function} is a function to call
|
|
later, and @var{args} are the arguments to give it when it is called.
|
|
The time @var{time} is specified as a string.
|
|
|
|
Absolute times may be specified in a wide variety of formats; this
|
|
function tries to accept all the commonly used date formats. Valid
|
|
formats include these two,
|
|
|
|
@example
|
|
@var{year}-@var{month}-@var{day} @var{hour}:@var{min}:@var{sec} @var{timezone}
|
|
|
|
@var{hour}:@var{min}:@var{sec} @var{timezone} @var{month}/@var{day}/@var{year}
|
|
@end example
|
|
|
|
@noindent
|
|
where in both examples all fields are numbers; the format that
|
|
@code{current-time-string} returns is also allowed, and many others
|
|
as well.
|
|
|
|
To specify a relative time, use numbers followed by units.
|
|
For example:
|
|
|
|
@table @samp
|
|
@item 1 min
|
|
denotes 1 minute from now.
|
|
@item 1 min 5 sec
|
|
denotes 65 seconds from now.
|
|
@item 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.
|
|
@end table
|
|
|
|
If @var{time} is a number (integer or floating point), that specifies a
|
|
relative time measured in seconds.
|
|
|
|
The argument @var{repeat} specifies how often to repeat the call. If
|
|
@var{repeat} is @code{nil}, there are no repetitions; @var{function} is
|
|
called just once, at @var{time}. If @var{repeat} is a number, it
|
|
specifies a repetition period measured in seconds.
|
|
|
|
In most cases, @var{repeat} has no effect on when @emph{first} call
|
|
takes place---@var{time} 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
|
|
@code{cancel-timer} (see below).
|
|
@end defun
|
|
|
|
@defmac with-timeout (seconds timeout-forms@dots{}) body@dots{}
|
|
Execute @var{body}, but give up after @var{seconds} seconds. If
|
|
@var{body} finishes before the time is up, @code{with-timeout} returns
|
|
the value of the last form in @var{body}. If, however, the execution of
|
|
@var{body} 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
|
|
@var{body} 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
|
|
@var{body} 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
|
|
@var{body} that waits for input, not one that does a long computation.
|
|
@end 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}.
|
|
|
|
@defun 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.
|
|
|
|
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
|
|
non-@code{nil}, 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} (see below).
|
|
@end defun
|
|
|
|
@cindex 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 became idle. Even if its @var{repeat} is true, 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, 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.
|
|
|
|
@defun cancel-timer timer
|
|
Cancel the requested action for @var{timer}, which should be a value
|
|
previously returned by @code{run-at-time} or @code{run-with-idle-timer}.
|
|
This cancels the effect of that call to @code{run-at-time}; the arrival
|
|
of the specified time will not cause anything special to happen.
|
|
@end defun
|
|
|
|
@node Terminal Input
|
|
@section Terminal Input
|
|
@cindex terminal input
|
|
|
|
This section describes functions and variables for recording or
|
|
manipulating terminal input. See @ref{Display}, for related
|
|
functions.
|
|
|
|
@menu
|
|
* Input Modes:: Options for how input is processed.
|
|
* Translating Input:: Low level conversion of some characters or events
|
|
into others.
|
|
* Recording Input:: Saving histories of recent or all input events.
|
|
@end menu
|
|
|
|
@node Input Modes
|
|
@subsection Input Modes
|
|
@cindex input modes
|
|
@cindex terminal input modes
|
|
|
|
@defun set-input-mode interrupt flow meta quit-char
|
|
This function sets the mode for reading keyboard input. If
|
|
@var{interrupt} is non-null, then Emacs uses input interrupts. If it is
|
|
@code{nil}, 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 non-@code{nil}, 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. @xref{Flow Control}.
|
|
|
|
@c 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.
|
|
|
|
@c Emacs 19 feature
|
|
If @var{quit-char} is non-@code{nil}, it specifies the character to
|
|
use for quitting. Normally this character is @kbd{C-g}.
|
|
@xref{Quitting}.
|
|
@end defun
|
|
|
|
The @code{current-input-mode} function returns the input mode settings
|
|
Emacs is currently using.
|
|
|
|
@c Emacs 19 feature
|
|
@defun current-input-mode
|
|
This function returns 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:
|
|
@table @var
|
|
@item interrupt
|
|
is non-@code{nil} when Emacs is using interrupt-driven input. If
|
|
@code{nil}, Emacs is using @sc{cbreak} mode.
|
|
@item flow
|
|
is non-@code{nil} 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}.
|
|
@item 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.
|
|
@item quit
|
|
is the character Emacs currently uses for quitting, usually @kbd{C-g}.
|
|
@end table
|
|
@end defun
|
|
|
|
@node Translating Input
|
|
@subsection Translating Input Events
|
|
@cindex translating input events
|
|
|
|
This section describes features for translating input events into
|
|
other input events before they become part of key sequences. These
|
|
features apply to each event in the order they are described here: each
|
|
event is first modified according to @code{extra-keyboard-modifiers},
|
|
then translated through @code{keyboard-translate-table} (if applicable),
|
|
and finally decoded with the specified keyboard coding system. If it is
|
|
being read as part of a key sequence, it is then added to the sequence
|
|
being read; then subsequences containing it are checked first with
|
|
@code{function-key-map} and then with @code{key-translation-map}.
|
|
|
|
@c Emacs 19 feature
|
|
@defvar extra-keyboard-modifiers
|
|
This variable lets Lisp programs ``press'' the modifier keys on the
|
|
keyboard. The value is a bit mask:
|
|
|
|
@table @asis
|
|
@item 1
|
|
The @key{SHIFT} key.
|
|
@item 2
|
|
The @key{LOCK} key.
|
|
@item 4
|
|
The @key{CTL} key.
|
|
@item 8
|
|
The @key{META} key.
|
|
@end table
|
|
|
|
Each time the user types a keyboard key, it is altered as if the
|
|
modifier keys specified in the bit mask were held down.
|
|
|
|
When using a window system, the program can ``press'' any of the
|
|
modifier keys in this way. Otherwise, only the @key{CTL} and @key{META}
|
|
keys can be virtually pressed.
|
|
@end defvar
|
|
|
|
@defvar keyboard-translate-table
|
|
This variable is the translate table for keyboard characters. It lets
|
|
you reshuffle the keys on the keyboard without changing any command
|
|
bindings. Its value is normally a char-table, or else @code{nil}.
|
|
|
|
If @code{keyboard-translate-table} is a char-table, then each character
|
|
read from the keyboard is looked up in this character. If the value
|
|
found there is non-@code{nil}, then it is used instead of the
|
|
actual input character.
|
|
|
|
In the example below, we set @code{keyboard-translate-table} to a
|
|
char-table. Then we fill it in to swap the characters @kbd{C-s} and
|
|
@kbd{C-\} and the characters @kbd{C-q} and @kbd{C-^}. Subsequently,
|
|
typing @kbd{C-\} has all the usual effects of typing @kbd{C-s}, and vice
|
|
versa. (@xref{Flow Control} for more information on this subject.)
|
|
|
|
@cindex flow control example
|
|
@example
|
|
@group
|
|
(defun evade-flow-control ()
|
|
"Replace C-s with C-\ and C-q with C-^."
|
|
(interactive)
|
|
@end group
|
|
@group
|
|
(setq keyboard-translate-table
|
|
(make-char-table 'keyboard-translate-table nil))
|
|
@end group
|
|
@group
|
|
;; @r{Swap @kbd{C-s} and @kbd{C-\}.}
|
|
(aset keyboard-translate-table ?\034 ?\^s)
|
|
(aset keyboard-translate-table ?\^s ?\034)
|
|
@end group
|
|
@group
|
|
;; @r{Swap @kbd{C-q} and @kbd{C-^}.}
|
|
(aset keyboard-translate-table ?\036 ?\^q)
|
|
(aset keyboard-translate-table ?\^q ?\036))
|
|
@end group
|
|
@end example
|
|
|
|
Note that this translation is the first thing that happens to a
|
|
character after it is read from the terminal. Record-keeping features
|
|
such as @code{recent-keys} and dribble files record the characters after
|
|
translation.
|
|
@end defvar
|
|
|
|
@defun keyboard-translate from to
|
|
This function modifies @code{keyboard-translate-table} to translate
|
|
character code @var{from} into character code @var{to}. It creates
|
|
the keyboard translate table if necessary.
|
|
@end defun
|
|
|
|
The remaining translation features translate subsequences of key
|
|
sequences being read. They are implemented in @code{read-key-sequence}
|
|
and have no effect on input read with @code{read-event}.
|
|
|
|
@defvar function-key-map
|
|
This variable holds a keymap that describes the character sequences sent
|
|
by function keys on an ordinary character terminal. This keymap has the
|
|
same structure as other keymaps, but is used differently: it specifies
|
|
translations to make while reading key sequences, rather than bindings
|
|
for key sequences.
|
|
|
|
If @code{function-key-map} ``binds'' a key sequence @var{k} to a vector
|
|
@var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a
|
|
key sequence, it is replaced with the events in @var{v}.
|
|
|
|
For example, VT100 terminals send @kbd{@key{ESC} O P} when the
|
|
keypad @key{PF1} key is pressed. Therefore, we want Emacs to translate
|
|
that sequence of events into the single event @code{pf1}. We accomplish
|
|
this by ``binding'' @kbd{@key{ESC} O P} to @code{[pf1]} in
|
|
@code{function-key-map}, when using a VT100.
|
|
|
|
Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c
|
|
@key{ESC} O P}; later the function @code{read-key-sequence} translates
|
|
this back into @kbd{C-c @key{PF1}}, which it returns as the vector
|
|
@code{[?\C-c pf1]}.
|
|
|
|
Entries in @code{function-key-map} are ignored if they conflict with
|
|
bindings made in the minor mode, local, or global keymaps. The intent
|
|
is that the character sequences that function keys send should not have
|
|
command bindings in their own right---but if they do, the ordinary
|
|
bindings take priority.
|
|
|
|
The value of @code{function-key-map} is usually set up automatically
|
|
according to the terminal's Terminfo or Termcap entry, but sometimes
|
|
those need help from terminal-specific Lisp files. Emacs comes with
|
|
terminal-specific files for many common terminals; their main purpose is
|
|
to make entries in @code{function-key-map} beyond those that can be
|
|
deduced from Termcap and Terminfo. @xref{Terminal-Specific}.
|
|
@end defvar
|
|
|
|
@defvar key-translation-map
|
|
This variable is another keymap used just like @code{function-key-map}
|
|
to translate input events into other events. It differs from
|
|
@code{function-key-map} in two ways:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{key-translation-map} goes to work after @code{function-key-map} is
|
|
finished; it receives the results of translation by
|
|
@code{function-key-map}.
|
|
|
|
@item
|
|
@code{key-translation-map} overrides actual key bindings. For example,
|
|
if @kbd{C-x f} has a binding in @code{key-translation-map}, that
|
|
translation takes effect even though @kbd{C-x f} also has a key binding
|
|
in the global map.
|
|
@end itemize
|
|
|
|
The intent of @code{key-translation-map} is for users to map one
|
|
character set to another, including ordinary characters normally bound
|
|
to @code{self-insert-command}.
|
|
@end defvar
|
|
|
|
@cindex key translation function
|
|
You can use @code{function-key-map} or @code{key-translation-map} for
|
|
more than simple aliases, by using a function, instead of a key
|
|
sequence, as the ``translation'' of a key. Then this function is called
|
|
to compute the translation of that key.
|
|
|
|
The key translation function receives one argument, which is the prompt
|
|
that was specified in @code{read-key-sequence}---or @code{nil} if the
|
|
key sequence is being read by the editor command loop. In most cases
|
|
you can ignore the prompt value.
|
|
|
|
If the function reads input itself, it can have the effect of altering
|
|
the event that follows. For example, here's how to define @kbd{C-c h}
|
|
to turn the character that follows into a Hyper character:
|
|
|
|
@example
|
|
@group
|
|
(defun hyperify (prompt)
|
|
(let ((e (read-event)))
|
|
(vector (if (numberp e)
|
|
(logior (lsh 1 24) e)
|
|
(if (memq 'hyper (event-modifiers e))
|
|
e
|
|
(add-event-modifier "H-" e))))))
|
|
|
|
(defun add-event-modifier (string e)
|
|
(let ((symbol (if (symbolp e) e (car e))))
|
|
(setq symbol (intern (concat string
|
|
(symbol-name symbol))))
|
|
@end group
|
|
@group
|
|
(if (symbolp e)
|
|
symbol
|
|
(cons symbol (cdr e)))))
|
|
|
|
(define-key function-key-map "\C-ch" 'hyperify)
|
|
@end group
|
|
@end example
|
|
|
|
Finally, if you have enabled keyboard character set decoding using
|
|
@code{set-keyboard-coding-system}, decoding is done after the
|
|
translations listed above. @xref{Specifying Coding Systems}. In future
|
|
Emacs versions, character set decoding may be done before the other
|
|
translations.
|
|
|
|
@node Recording Input
|
|
@subsection Recording Input
|
|
|
|
@defun recent-keys
|
|
This function returns a vector containing the last 100 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.)
|
|
@end defun
|
|
|
|
@deffn Command open-dribble-file filename
|
|
@cindex 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.
|
|
|
|
@example
|
|
@group
|
|
(open-dribble-file "~/dribble")
|
|
@result{} nil
|
|
@end group
|
|
@end example
|
|
@end deffn
|
|
|
|
See also the @code{open-termscript} function (@pxref{Terminal Output}).
|
|
|
|
@node Terminal Output
|
|
@section Terminal Output
|
|
@cindex terminal output
|
|
|
|
The terminal output functions send output to the 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.
|
|
|
|
@defvar 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---even when using a window system. (We designed it
|
|
this way despite the fact that a window system has no true ``output
|
|
speed'', to give you a way to tune these decisions.)
|
|
|
|
The value is measured in baud.
|
|
@end 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}.
|
|
|
|
@defun baud-rate
|
|
This obsolete function returns the value of the variable
|
|
@code{baud-rate}.
|
|
@end defun
|
|
|
|
@defun send-string-to-terminal string
|
|
This function sends @var{string} to the terminal without alteration.
|
|
Control characters in @var{string} have terminal-dependent effects.
|
|
|
|
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):
|
|
|
|
@example
|
|
@group
|
|
(send-string-to-terminal "\eF4\^U\^F")
|
|
@result{} nil
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@deffn Command open-termscript filename
|
|
@cindex 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
|
|
@code{nil}. 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.
|
|
|
|
See also @code{open-dribble-file} in @ref{Terminal Input}.
|
|
|
|
@example
|
|
@group
|
|
(open-termscript "../junk/termscript")
|
|
@result{} nil
|
|
@end group
|
|
@end example
|
|
@end deffn
|
|
|
|
@node Special Keysyms
|
|
@section System-Specific X11 Keysyms
|
|
|
|
To define system-specific X11 keysyms, set the variable
|
|
@code{system-key-alist}.
|
|
|
|
@defvar system-key-alist
|
|
This variable's value should be an alist with one element for each
|
|
system-specific keysym. An element has this form: @code{(@var{code}
|
|
. @var{symbol})}, where @var{code} is the numeric keysym code (not
|
|
including the ``vendor specific'' bit,
|
|
@ifinfo
|
|
-2**28,
|
|
@end ifinfo
|
|
@tex
|
|
$-2^{28}$,
|
|
@end 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
|
|
@ifinfo
|
|
-2**28
|
|
@end ifinfo
|
|
@tex
|
|
$-2^{28}$
|
|
@end 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}.
|
|
@end defvar
|
|
|
|
@node Flow Control
|
|
@section Flow Control
|
|
@cindex flow control characters
|
|
|
|
This section attempts to answer the question ``Why does Emacs use
|
|
flow-control characters in its command character set?'' For a second
|
|
view on this issue, read the comments on flow control in the
|
|
@file{emacs/INSTALL} file from the distribution; for help with Termcap
|
|
entries and DEC terminal concentrators, see @file{emacs/etc/TERMS}.
|
|
|
|
@cindex @kbd{C-s}
|
|
@cindex @kbd{C-q}
|
|
At one time, most terminals did not need flow control, and none used
|
|
@code{C-s} and @kbd{C-q} for flow control. Therefore, the choice of
|
|
@kbd{C-s} and @kbd{C-q} as command characters for searching and quoting
|
|
was natural and uncontroversial. With so many commands needing key
|
|
assignments, of course we assigned meanings to nearly all @sc{ASCII}
|
|
control characters.
|
|
|
|
Later, some terminals were introduced which required these characters
|
|
for flow control. They were not very good terminals for full-screen
|
|
editing, so Emacs maintainers ignored them. In later years, flow
|
|
control with @kbd{C-s} and @kbd{C-q} became widespread among terminals,
|
|
but by this time it was usually an option. And the majority of Emacs
|
|
users, who can turn flow control off, did not want to switch to less
|
|
mnemonic key bindings for the sake of flow control.
|
|
|
|
So which usage is ``right''---Emacs's or that of some terminal and
|
|
concentrator manufacturers? This question has no simple answer.
|
|
|
|
One reason why we are reluctant to cater to the problems caused by
|
|
@kbd{C-s} and @kbd{C-q} is that they are gratuitous. There are other
|
|
techniques (albeit less common in practice) for flow control that
|
|
preserve transparency of the character stream. Note also that their use
|
|
for flow control is not an official standard. Interestingly, on the
|
|
model 33 teletype with a paper tape punch (around 1970), @kbd{C-s} and
|
|
@kbd{C-q} were sent by the computer to turn the punch on and off!
|
|
|
|
As window systems and PC terminal emulators replace character-only
|
|
terminals, the flow control problem is gradually disappearing. For the
|
|
mean time, Emacs provides a convenient way of enabling flow control if
|
|
you want it: call the function @code{enable-flow-control}.
|
|
|
|
@deffn Command enable-flow-control
|
|
This function enables use of @kbd{C-s} and @kbd{C-q} for output flow
|
|
control, and provides the characters @kbd{C-\} and @kbd{C-^} as aliases
|
|
for them using @code{keyboard-translate-table} (@pxref{Translating Input}).
|
|
@end deffn
|
|
|
|
You can use the function @code{enable-flow-control-on} in your
|
|
@file{.emacs} file to enable flow control automatically on certain
|
|
terminal types.
|
|
|
|
@defun enable-flow-control-on &rest termtypes
|
|
This function enables flow control, and the aliases @kbd{C-\} and @kbd{C-^},
|
|
if the terminal type is one of @var{termtypes}. For example:
|
|
|
|
@smallexample
|
|
(enable-flow-control-on "vt200" "vt300" "vt101" "vt131")
|
|
@end smallexample
|
|
@end defun
|
|
|
|
Here is how @code{enable-flow-control} does its job:
|
|
|
|
@enumerate
|
|
@item
|
|
@cindex @sc{cbreak}
|
|
It sets @sc{cbreak} mode for terminal input, and tells the operating
|
|
system to handle flow control, with @code{(set-input-mode nil t)}.
|
|
|
|
@item
|
|
It sets up @code{keyboard-translate-table} to translate @kbd{C-\} and
|
|
@kbd{C-^} into @kbd{C-s} and @kbd{C-q}. Except at its very
|
|
lowest level, Emacs never knows that the characters typed were anything
|
|
but @kbd{C-s} and @kbd{C-q}, so you can in effect type them as @kbd{C-\}
|
|
and @kbd{C-^} even when they are input for other commands.
|
|
@xref{Translating Input}.
|
|
@end enumerate
|
|
|
|
If the terminal is the source of the flow control characters, then once
|
|
you enable kernel flow control handling, you probably can make do with
|
|
less padding than normal for that terminal. You can reduce the amount
|
|
of padding by customizing the Termcap entry. You can also reduce it by
|
|
setting @code{baud-rate} to a smaller value so that Emacs uses a smaller
|
|
speed when calculating the padding needed. @xref{Terminal Output}.
|
|
|
|
@node Batch Mode
|
|
@section Batch Mode
|
|
@cindex batch mode
|
|
@cindex noninteractive use
|
|
|
|
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}, and @samp{-f @var{function}}, which
|
|
calls @var{function} with no arguments.
|
|
|
|
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. 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.)
|
|
|
|
@defvar noninteractive
|
|
This variable is non-@code{nil} when Emacs is running in batch mode.
|
|
@end defvar
|