@chapter Operating System Interface
This chapter is about starting and getting out of Emacs, access to
-values in the operating system environment, and terminal input, output
+values in the operating system environment, and terminal input, output,
and flow control.
@xref{Building Emacs}, for related information. See also
* 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 a string, or
+ to calendrical data (or vice versa).
* Timers:: Setting a timer to call a function at a certain time.
* Terminal Input:: Recording terminal input for debugging.
* Terminal Output:: Recording terminal output for debugging.
using a window system. This library's name is
@file{term/@var{windowsystem}-win.el}.
+@item
+It processes the initial options. (Some of them are handled
+even earlier than this.)
+
@item
It initializes the X window frame and faces, if appropriate.
@item
It loads the file @file{~/.emacs} unless @samp{-q} was specified on
-command line. (This is not done in @samp{-batch} mode.) The @samp{-u}
+the command line. (This is not done in @samp{-batch} mode.) The @samp{-u}
option can specify the user name whose home directory should be used
instead of @file{~}.
@item
It loads the library @file{default} unless @code{inhibit-default-init}
is non-@code{nil}. (This is not done in @samp{-batch} mode or if
-@samp{-q} was specified on command line.) The library's file name is
-usually @file{default.el}.
+@samp{-q} was specified on the command line.) The library's file name
+is usually @file{default.el}.
@cindex @file{default.el}
@item
that with @code{inhibit-startup-echo-area-message}.
@item
-It processes any remaining command line arguments.
+It processes the action arguments from the command line.
@item
It runs @code{term-setup-hook}.
It runs @code{window-setup-hook}. @xref{Window Systems}.
@item
-It displays copyleft, nonwarranty and basic use information, provided
+It displays copyleft, nonwarranty, and basic use information, provided
there were no remaining command line arguments (a few steps above) and
the value of @code{inhibit-startup-message} is @code{nil}.
@end enumerate
loads this @emph{before} the user's init file. You can inhibit the
loading of this file with the option @samp{-no-site-file}.
+@defvar site-run-file
+This variable specifies the site-customization file to load
+before the user's init file. Its normal value is @code{"site-start"}.
+@end defvar
+
If there is a great deal of code in your @file{.emacs} file, you
should move it into another file named @file{@var{something}.el},
byte-compile it (@pxref{Byte Compilation}), and make your @file{.emacs}
@end defvar
@defvar term-setup-hook
-This variable is a normal hook which Emacs runs after loading your
+This variable is a normal hook that Emacs runs after loading your
@file{.emacs} file, the default initialization file (if any) and the
terminal-specific Lisp file.
@end ignore
@defun command-line
-This function parses the command line which Emacs was called with,
+This function parses the command line that Emacs was called with,
processes it, loads the user's @file{.emacs} file and displays the
-initial nonwarranty information, etc.
+startup messages.
@end defun
@defvar command-line-processed
This variable's value is a list of functions for handling an
unrecognized command-line argument. Each time the next argument to be
processed has no special meaning, the functions in this list are called,
-in the order they appear, until one of them returns a non-@code{nil}
+in order of appearance, until one of them returns a non-@code{nil}
value.
These functions are called with no arguments. They can access the
non-@code{nil}, then @code{suspend-emacs} returned immediately without
actually suspending anything.
-After the user resumes Emacs, it runs the normal 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,
system, the user's @sc{uid}, and so on.
@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 symbols
-for the operating systems that Emacs can run on up to version 19.1.
+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 aix-v3
@item berkeley-unix
Berkeley BSD.
+@item dgux
+Data General DGUX operating system.
+
+@item gnu
+A GNU system (using the GNU kernel, which consists of the HURD and Mach).
+
+@item gnu/linux
+A variant GNU system using the Linux kernel.
+
@item hpux
-Hewlett-Packard operating system.
+Hewlett-Packard HPUX operating system.
@item irix
Silicon Graphics Irix system.
-@item linux
-The free Linux operating system.
+@item ms-dos
+Microsoft MS-DOS ``operating system.''
+
+@item next-mach
+NeXT Mach-based system.
@item rtu
Masscomp RTU, UCB universe.
@item vax-vms
VAX VMS.
+@item windows-nt
+Microsoft windows NT.
+
@item xenix
SCO Xenix 386.
@end table
@end example
@end defun
+@vindex system-name
+ 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},
@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.
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 near where the Emacs executable was found.
+locations, but can find them in a directory related somehow to the one
+containing the Emacs executable.
@end defvar
@defun load-average
-This function returns the current 1 minute, 5 minute and 15 minute
+This function returns the current 1-minute, 5-minute and 15-minute
load averages in a list. The values are integers that are 100 times
the system load averages. (The load averages indicate the number of
processes trying to run.)
@node User Identification
@section User Identification
-@defun user-login-name
-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}.
+@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
@end example
@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.
This function returns the current time and date as a humanly-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. However, it would be wise to
-count the characters from the beginning of the string rather than from
-the end, as additional information may be added at the end.
+@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 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 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 below) and from @code{file-attributes} (@pxref{File Attributes}).
+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
@var{high} * 2**16 + @var{low}.
@end ifinfo
@tex
-$high*-2^{16}+low$.
+$high*2^{16}+low$.
@end tex
The third element, @var{microsec}, gives the microseconds since the
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 below) and from @code{file-attributes} (@pxref{File Attributes}).
+(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 -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 C), it
+is equivalent to @samp{%D}.
+@item %X
+This has a locale-specific meaning. In the default locale (named 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
+@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
+
+Note that 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}) 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
@end defun
@node Timers
-@section 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.
-You can set up a timer to call a function at a specified future time.
+ Emacs cannot run a timer 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-char} 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}
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; The form
+Absolute times may be specified in a variety of formats; The form
@samp{@var{hour}:@var{min}:@var{sec} @var{timezone}
@var{month}/@var{day}/@var{year}}, where all fields are numbers, works;
the format that @code{current-time-string} returns is also allowed.
denotes exactly 103 months, 123 days, and 10862 seconds from now.
@end table
-If @var{time} is an integer, that specifies a relative time measured in
-seconds.
+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 an integer, it
-specifies a repetition period measured in seconds.
+called just once, at @var{time}. If @var{repeat} is a number, it
+specifies a repetition period measured in seconds. In any case,
+@var{repeat} has no effect on when @emph{first} call takes
+place---@var{time} alone specifies that.
+
+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 set 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
+have little effect on idle timers. 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}. 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.
+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
@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.
+@code{nil}, then it uses @sc{cbreak} mode. 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 terminal. This has no effect except
+@kbd{C-s}) flow control for output to the terminal. This has no effect except
in @sc{cbreak} mode. @xref{Flow Control}.
The default setting is system dependent. Some systems always use
flow control for output to the terminal. This value has no effect
unless @var{interrupt} is non-@code{nil}.
@item meta
-is non-@code{t} if Emacs treats the eighth bit of input characters as
+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.
@end table
@end defun
-@defvar meta-flag
-This variable used to control whether to treat the eight bit in keyboard
-input characters as the @key{Meta} bit. @code{nil} meant no, and
-anything else meant yes. This variable existed in Emacs versions 18 and
-earlier but no longer exists in Emacs 19; use @code{set-input-mode}
-instead.
-@end defvar
-
@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.
+ 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).
+If it is being read as part of a key sequence, it is then added to the
+sequece 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
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 you use X windows, the program can ``press'' any of the modifier
+When using X windows, 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
or enlarges the 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 @code{read-char}.
+
@defvar function-key-map
-This variable holds a keymap which describes the character sequences
+This variable holds a keymap that describes the character sequences
sent by function keys on an ordinary character terminal. This keymap
-uses the data structure as other keymaps, but is used differently: it
-specifies translations to make while reading events.
+uses the same data structure as other keymaps, but is used differently: it
+specifies translations to make while reading event 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
@code{function-key-map}.
@item
-@code{key-translation-map} overrides actual key bindings.
+@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
to turn the character that follows into a Hyper character:
@example
+@group
(defun hyperify (prompt)
(let ((e (read-event)))
(vector (if (numberp 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
@pindex iso-transl
not they were used as parts of key sequences. Thus, you always get the
last 100 inputs, not counting keyboard macros. (Events from keyboard
macros are excluded because they are less interesting for debugging; it
-should be enough to see the events which invoked the macros.)
+should be enough to see the events that invoked the macros.)
@end defun
@deffn Command open-dribble-file filename
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
+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.)
It is not a problem if the alist defines keysyms for other X servers, 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 X terminal and cannot be
+buffer-local. @xref{Multiple Displays}.
@end defvar
@node Flow Control
model 33 teletype with a paper tape punch (which is very old), @kbd{C-s}
and @kbd{C-q} were sent by the computer to turn the punch on and off!
- GNU Emacs version 19 provides a convenient way of enabling flow
-control if you want it: call the function @code{enable-flow-control}.
+ As X servers and other window systems replace character-only
+terminals, this problem is gradually being cured. For the mean time,
+Emacs provides a convenient way of enabling flow control if you want it:
+call the function @code{enable-flow-control}.
@defun enable-flow-control
This function enables use of @kbd{C-s} and @kbd{C-q} for output flow
@item
It sets up @code{keyboard-translate-table} to translate @kbd{C-\} and
-@kbd{C-^} into @kbd{C-s} and @kbd{C-q} were typed. Except at its very
+@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.
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 output descriptor when
+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.)
HCoop / bpt / emacs.git / blobdiff