@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
-@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+@c Copyright (C) 1990-1995, 1998-1999, 2001-2012
@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../../info/os
* 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
+* 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.
It runs the normal hook @code{before-init-hook}.
@item
-It initializes the window frame and faces, if appropriate, and turns
-on the menu bar and tool bar, if the initial frame needs them.
+It initializes the initial frame's faces, and turns on the menu bar
+and tool bar if needed.
@item
It loads the library @file{site-start}, if it exists. This is not
@code{initial-major-mode}.
@item
-If started on a text-only terminal, it loads the terminal-specific
+If started on a text terminal, it loads the terminal-specific
Lisp library, which is specified by the variable
@code{term-file-prefix} (@pxref{Terminal-Specific}). This is not done
in @code{--batch} mode, nor if @code{term-file-prefix} is @code{nil}.
killing Emacs is @code{kill-emacs}.
@deffn Command kill-emacs &optional exit-data
-This command exits the Emacs process and kills it.
+This command calls the hook @code{kill-emacs-hook}, then 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
+If @var{exit-data} is an integer, that is used as the exit status of
+the Emacs process. (This is useful primarily in batch operation; see
@ref{Batch Mode}.)
If @var{exit-data} is a string, its contents are stuffed into the
input) can read them.
@end deffn
- 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
-@code{save-buffers-kill-emacs}, the higher level function from which
-@code{kill-emacs} is usually called.
+@cindex SIGTERM
+@cindex SIGHUP
+@cindex SIGINT
+@cindex operating system signal
+ The @code{kill-emacs} function is normally called via the
+higher-level command @kbd{C-x C-c}
+(@code{save-buffers-kill-terminal}). @xref{Exiting,,, emacs, The GNU
+Emacs Manual}. It is also called automatically if Emacs receives a
+@code{SIGTERM} or @code{SIGHUP} operating system signal (e.g. when the
+controlling terminal is disconnected), or if it receives a
+@code{SIGINT} signal while running in batch mode (@pxref{Batch Mode}).
-@defvar 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
-@code{nil}, @code{save-buffers-kill-emacs} does not kill Emacs, and
-does not run the remaining functions in this hook. Calling
-@code{kill-emacs} directly does not run this hook.
+@defvar kill-emacs-hook
+This normal hook is run by @code{kill-emacs}, before it kills Emacs.
+
+Because @code{kill-emacs} can be called in situations where user
+interaction is impossible (e.g. when the terminal is disconnected),
+functions on this hook should not attempt to interact with the user.
+If you want to interact with the user when Emacs is shutting down, use
+@code{kill-emacs-query-functions}, described below.
@end defvar
-@defvar 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
-@code{kill-emacs} which runs the functions in this hook.
-
-@code{kill-emacs} may be invoked directly (that is not via
-@code{save-buffers-kill-emacs}) 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
-@code{kill-emacs-query-functions}; if it needs to run regardless of
-how Emacs is killed, put it on @code{kill-emacs-hook}.
+ When Emacs is killed, all the information in the Emacs process,
+aside from files that have been saved, is lost. Because killing Emacs
+inadvertently can lose a lot of work, the
+@code{save-buffers-kill-terminal} command queries for confirmation if
+you have buffers that need saving or subprocesses that are running.
+It also runs the abnormal hook @code{kill-emacs-query-functions}:
+
+@defvar kill-emacs-query-functions
+When @code{save-buffers-kill-terminal} is killing Emacs, it calls the
+functions in this hook, after asking the standard questions and before
+calling @code{kill-emacs}. The functions are called in order of
+appearance, with no arguments. Each function can ask for additional
+confirmation from the user. If any of them returns @code{nil},
+@code{save-buffers-kill-emacs} does not kill Emacs, and does not run
+the remaining functions in this hook. Calling @code{kill-emacs}
+directly does not run this hook.
@end defvar
@node Suspending Emacs
@subsection Suspending Emacs
@cindex suspending Emacs
- On text-only terminals, it is possible to @dfn{suspend Emacs}, which
+ On text terminals, it is possible to @dfn{suspend Emacs}, which
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
@deffn Command suspend-frame
This command @dfn{suspends} a frame. For GUI frames, it calls
-@code{iconify-frame} (@pxref{Visibility of Frames}); for text-only
-frames, it calls either @code{suspend-emacs} or @code{suspend-tty},
-depending on whether the frame is displayed on the controlling
-terminal device or not.
+@code{iconify-frame} (@pxref{Visibility of Frames}); for frames on
+text terminals, it calls either @code{suspend-emacs} or
+@code{suspend-tty}, depending on whether the frame is displayed on the
+controlling terminal device or not.
@end deffn
@node System Environment
@xref{Definition of file-attributes}.
@end defun
+@defun 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
+@code{file-attributes} (@pxref{Definition of file-attributes}).
+
+@emph{Warning}: Since the result is floating point, it may not be
+exact. Do not use this function if precise time stamps are required.
+@end defun
+
@defun current-time-zone &optional time-value
This function returns a list describing the time zone that the user is
in.
@code{file-attributes}. @xref{Definition of file-attributes}.
@end defun
-@defun set-time-zone-rule tz
-This function specifies the local time zone according to @var{tz}. If
-@var{tz} 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.
-@end defun
-
-@defun 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
-@code{file-attributes} (@pxref{Definition of file-attributes}).
-
-@emph{Warning}: Since the result is floating point, it may not be
-exact. Do not use this function if precise time stamps are required.
-@end defun
+The current time zone is determined by the @samp{TZ} environment
+variable. @xref{System Environment}. For example, you can tell Emacs
+to use universal time with @code{(setenv "TZ" "UTC0")}. If @samp{TZ}
+is not in the environment, Emacs uses a platform-dependent default
+time zone.
@node Time Conversion
@section Time Conversion
from the functions @code{current-time} (@pxref{Time of Day}) and
@code{file-attributes} (@pxref{Definition of file-attributes}).
- Many operating systems are limited to time values that contain 32 bits
+ Many 32-bit 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.
+1901-12-13 20:45:52 UTC through 2038-01-19 03:14:07 UTC. However, 64-bit
+and some 32-bit 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
This stands for the minute (00-59).
@item %n
This stands for a newline.
+@item %N
+This stands for the nanoseconds (000000000-999999999). To ask for
+fewer digits, use @samp{%3N} for milliseconds, @samp{%6N} for
+microseconds, etc. Any excess digits are discarded, without rounding.
+Currently Emacs time stamps are at best microsecond resolution so the
+last three digits generated by plain @samp{%N} are always zero.
@item %p
This stands for @samp{AM} or @samp{PM}, as appropriate.
@item %r
This variable is ignored if the given @var{library} is statically
linked into Emacs.
@end defvar
-
-@ignore
- arch-tag: 8378814a-30d7-467c-9615-74a80b9988a7
-@end ignore