From 339902ec4ad4c746e35432a43983593d7615057f Mon Sep 17 00:00:00 2001 From: Luc Teirlinck Date: Wed, 7 Jul 2004 01:13:55 +0000 Subject: Various small changes in addition to: (Killing Emacs): Expand and clarify description of `kill-emacs-query-functions' and `kill-emacs-hook'. (System Environment): Expand and clarify description of `getenv' and `setenv'. (Timers): Clarify description of `run-at-time'. (Translating Input): Correct description of `extra-keyboard-modifiers'. (Flow Control): Correct description of `enable-flow-control'. --- lispref/ChangeLog | 12 +++ lispref/os.texi | 213 +++++++++++++++++++++++++++++++++--------------------- 2 files changed, 143 insertions(+), 82 deletions(-) (limited to 'lispref') diff --git a/lispref/ChangeLog b/lispref/ChangeLog index a27d59b72f..145aea753c 100644 --- a/lispref/ChangeLog +++ b/lispref/ChangeLog @@ -1,3 +1,15 @@ +2004-07-06 Luc Teirlinck + + * os.texi: Various small changes in addition to: + (Killing Emacs): Expand and clarify description of + `kill-emacs-query-functions' and `kill-emacs-hook'. + (System Environment): Expand and clarify description of `getenv' + and `setenv'. + (Timers): Clarify description of `run-at-time'. + (Translating Input): Correct description of + `extra-keyboard-modifiers'. + (Flow Control): Correct description of `enable-flow-control'. + 2004-07-06 Thien-Thi Nguyen * os.texi: Update copyright. diff --git a/lispref/os.texi b/lispref/os.texi index d52464e740..3e1b93339a 100644 --- a/lispref/os.texi +++ b/lispref/os.texi @@ -237,7 +237,7 @@ This normal hook is run, once, just before loading all the init files This normal hook is run, once, just after loading all the init files (the user's init file, @file{default.el}, and/or @file{site-start.el}), before loading the terminal-specific library and processing the -command-line arguments. +command-line action arguments. @end defvar @defvar emacs-startup-hook @@ -248,7 +248,7 @@ arguments, just before @code{term-setup-hook}. @defvar user-init-file @tindex user-init-file -This variable holds the file name of the user's init file. If the +This variable holds the absolute file name of the user's init file. If the actual init file loaded is a compiled file, such as @file{.emacs.elc}, the value refers to the corresponding source file. @end defvar @@ -471,20 +471,31 @@ 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}. +@code{save-buffers-kill-emacs}, the higher level function from which +@code{kill-emacs} is usually called. @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}, Emacs is not killed. +@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 @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 runs the functions in -this hook. This hook is not run in batch mode. +finished with all file saving and confirmation, it calls +@code{kill-emacs} which runs the functions in this hook. +@code{kill-emacs} does not run this hook in batch mode. + +@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}. @end defvar @node Suspending Emacs @@ -508,7 +519,7 @@ give input to some other job such as a shell merely by moving to a different window. Therefore, suspending is not allowed when Emacs is using a window system (X or MS Windows). -@defun suspend-emacs string +@defun suspend-emacs &optional string This function stops Emacs and returns control to the superior process. If and when the superior process resumes Emacs, @code{suspend-emacs} returns @code{nil} to its caller in Lisp. @@ -542,10 +553,10 @@ Emacs is suspended. But it is read and executed by the shell. (function (lambda () (or (y-or-n-p "Really suspend? ") - (error "Suspend cancelled"))))) + (error "Suspend canceled"))))) @result{} (lambda nil (or (y-or-n-p "Really suspend? ") - (error "Suspend cancelled"))) + (error "Suspend canceled"))) @end group @group (add-hook 'suspend-resume-hook @@ -694,8 +705,10 @@ Emacs was dumped. @xref{Building Emacs}.) @deffn Command 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}. +as a string. @var{var} should be a string. If @var{var} is undefined +in the environment, @code{getenv} returns @code{nil}. If returns +@samp{""} if @var{var} is set but null. Within Emacs, the environment +variable values are kept in the Lisp variable @code{process-environment}. @example @group @@ -717,11 +730,22 @@ HOME=/user/lewis @end deffn @c Emacs 19 feature -@deffn Command setenv variable value +@deffn Command setenv variable &optional 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. +@var{variable} to @var{value}. @var{variable} should be a string. +Internally, Emacs Lisp can handle any string. However, normally +@var{variable} should be a valid shell identifier, that is, a sequence +of letters, digits and underscores, starting with a letter or +underscore. Otherwise, errors may occur if subprocesses of Emacs try +to access the value of @var{variable}. If @var{value} is omitted or +@code{nil}, @code{setenv} removes @var{variable} from the environment. +Otherwise, @var{value} should be a string. + +@code{setenv} works by modifying @code{process-environment}; binding +that variable with @code{let} is also reasonable practice. + +@code{setenv} returns the new value of @var{variable}, or @code{nil} +if it removed @var{variable} from the environment. @end deffn @defvar process-environment @@ -801,6 +825,10 @@ an error. On some platforms, access to load averages requires installing Emacs as setuid or setgid so that it can read kernel information, and that usually isn't advisable. +If the 1-minute load average is available, but the 5- or 15-minute +averages are not, this function returns a shortened list containing +the available averages. + @example @group (load-average) @@ -820,12 +848,14 @@ lewis@@rocky[5] % uptime @end defun @defun emacs-pid -This function returns the process @acronym{ID} of the Emacs process. +This function returns the process @acronym{ID} of the Emacs process, +as an integer. @end defun @defvar tty-erase-char This variable holds the erase character that was selected in the system's terminal driver, before Emacs was started. +The value is @code{nil} if Emacs is running under a window system. @end defvar @defun setprv privilege-name &optional setp getprv @@ -836,7 +866,7 @@ 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} +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 @@ -845,8 +875,9 @@ indicating whether the privilege is currently enabled. @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 +This variable says which user's init files should be used by +Emacs---or @code{nil} if none. @code{""} stands for the user who +originally logged in. The value reflects command-line options such as @samp{-q} or @samp{-u @var{user}}. Lisp packages that load files of customizations, or any other sort of @@ -873,7 +904,8 @@ is set, that value is used. Otherwise, if the environment variable on the effective @acronym{UID}, not the real @acronym{UID}. If you specify @var{uid}, the value is the user name that corresponds -to @var{uid} (which should be an integer). +to @var{uid} (which should be an integer), or @code{nil} if there is +no such user. @example @group @@ -904,7 +936,7 @@ of the environment variable @code{NAME}, if that is set. If the Emacs job's user-id does not correspond to any known user (and provided @code{NAME} is not set), the value is @code{"unknown"}. -If @var{uid} is non-@code{nil}, then it should be an integer (a user-id) +If @var{uid} is non-@code{nil}, then it should be a number (a user-id) or a string (a login name). Then @code{user-full-name} returns the full name corresponding to that user-id or login name. If you specify a user-id or login name that isn't defined, it returns @code{nil}. @@ -956,7 +988,8 @@ 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}). +(@pxref{Definition of file-attributes}). @var{time-value} can also be +a cons of two integers, but this is considered obsolete. @example @group @@ -971,7 +1004,7 @@ two elements are integers. Thus, you can use times obtained from 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 (local time), which is +0:00 January 1, 1970 UTC (Coordinated Universal Time), which is @ifnottex @var{high} * 2**16 + @var{low}. @end ifnottex @@ -984,7 +1017,8 @@ start of the current second (or 0 for systems that return time with the resolution of only one second). The first two elements can be compared with file time values such as you -get with the function @code{file-attributes}. @xref{File Attributes}. +get with the function @code{file-attributes}. +@xref{Definition of file-attributes}. @end defun @c Emacs 19 feature @@ -1001,20 +1035,21 @@ 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}. +compute the value, the unknown elements of the list are @code{nil}. The argument @var{time-value}, if given, specifies a time to analyze -instead of the current time. The argument should 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}). +instead of the current time. The argument should have the same form +as for @code{current-time-string} (see above). Thus, you can use +times obtained from @code{current-time} (see above) and from +@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. +Universal Time. Otherwise, @var{tz} should be a string specifying a +time zone rule. @end defun @defun float-time &optional time-value @@ -1022,7 +1057,7 @@ 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), and it also accepts the output of @code{current-time} and +above). Thus, it accepts the output of @code{current-time} and @code{file-attributes}. @emph{Warning}: Since the result is floating point, it may not be @@ -1036,7 +1071,7 @@ exact. Do not use this function if precise time stamps are required. 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}). +@code{file-attributes} (@pxref{Definition of file-attributes}). Many operating systems are limited to time values that contain 32 bits of information; these systems typically handle only the times from @@ -1189,6 +1224,7 @@ Here is what the elements mean: @table @var @item seconds The number of seconds past the minute, as an integer between 0 and 59. +On some operating systems, this is 60 for leap seconds. @item minutes The number of minutes past the hour, as an integer between 0 and 59. @item hour @@ -1225,9 +1261,9 @@ 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. +@code{TZ} environment variable, @code{t} for Universal Time, or an +integer (as you would get from @code{decode-time}). The specified +zone is used without any further alteration for daylight 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 @@ -1309,15 +1345,18 @@ because most timer functions don't do a lot of work. Indeed, for a timer to call a function that takes substantial time to run is likely to be annoying. -@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. +@deffn Command run-at-time time repeat function &rest args +This sets up a timer that calls the function @var{function} with +arguments @var{args} at time @var{time}. If @var{repeat} is a number +(integer or floating point), the timer also runs every @var{repeat} +seconds after that. If @var{repeat} is @code{nil}, the timer runs +only once. + +@var{time} may specify an absolute or a relative time. 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, +function tries to accept all the commonly used date formats. The most +convenient formats are strings. Valid such formats include these two, @example @var{year}-@var{month}-@var{day} @var{hour}:@var{min}:@var{sec} @var{timezone} @@ -1330,7 +1369,7 @@ 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. +To specify a relative time as a string, use numbers followed by units. For example: @table @samp @@ -1345,13 +1384,9 @@ denotes exactly 103 months, 123 days, and 10862 seconds from now. For relative time values, Emacs considers a month to be exactly thirty days, and a year to be exactly 365.25 days. -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. +Not all convenient formats are strings. If @var{time} is a number +(integer or floating point), that specifies a relative time 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: @@ -1362,7 +1397,7 @@ 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 +@end deffn @defmac with-timeout (seconds timeout-forms@dots{}) body@dots{} Execute @var{body}, but give up after @var{seconds} seconds. If @@ -1388,7 +1423,7 @@ calls one of those primitives. So use @code{with-timeout} only with a 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 +@deffn Command run-with-idle-timer secs repeat function &rest args Set up a timer which runs when Emacs has been idle for @var{secs} seconds. The value of @var{secs} may be an integer or a floating point number. @@ -1400,7 +1435,7 @@ 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 +@end deffn @cindex idleness Emacs becomes ``idle'' when it starts waiting for user input, and it @@ -1426,8 +1461,8 @@ 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. +This cancels the effect of that call to one of these functions; the +arrival of the specified time will not cause anything special to happen. @end defun @node Terminal Input @@ -1450,7 +1485,7 @@ functions. @cindex input modes @cindex terminal input modes -@defun set-input-mode interrupt flow meta quit-char +@defun set-input-mode interrupt flow meta &optional 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 @@ -1523,31 +1558,30 @@ being read; then subsequences containing it are checked first with @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. +keyboard. The value is a character. Only the modifiers of the +character matter. Each time the user types a keyboard key, it is +altered as if those modifier keys were held down. For instance, if +you bind @code{extra-keyboard-modifiers} to @code{?\C-\M-a}, then all +keyboard input characters typed during the scope of the binding will +have the control and meta modifiers applied to them. The character +@code{?\C-@@}, equivalent to the integer 0, does not count as a control +character for this purpose, but as a character with no modifiers. +Thus, setting @code{extra-keyboard-modifiers} to zero cancels any +modification. 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. + +Note that this variable applies only to events that really come from +the keyboard, and has no effect on mouse events or any other events. @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}. +(It can also be a string or vector, but this is considered obsolete.) If @code{keyboard-translate-table} is a char-table (@pxref{Char-Tables}), then each character read from the keyboard is @@ -1587,6 +1621,11 @@ 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. + +Note also that this translation is done before the characters are +supplied to input methods (@pxref{Input Methods}). Use +@code{translation-table-for-input} (@pxref{Translation of Characters}), +if you want to translate characters after input methods operate. @end defvar @defun keyboard-translate from to @@ -1699,7 +1738,7 @@ to turn the character that follows into a Hyper character: 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 +translations listed above. @xref{Terminal I/O Encoding}. In future Emacs versions, character set decoding may be done before the other translations. @@ -1804,7 +1843,10 @@ 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}. +You close the termscript file by calling this function with an +argument of @code{nil}. + +See also @code{open-dribble-file} in @ref{Recording Input}. @example @group @@ -1969,10 +2011,16 @@ 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}). +@deffn Command enable-flow-control &optional arg +When @var{arg} is a positive integer, 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}). + +When @var{arg} is a negative integer or zero, it disables these +features. When @var{arg} is @code{nil} or omitted, it toggles. +Interactively, @var{arg} is the prefix argument. If non-@code{nil}, +its numeric value is used. @end deffn You can use the function @code{enable-flow-control-on} in your @@ -1994,7 +2042,7 @@ if the terminal type is one of @var{termtypes}. For example: @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)}. +system to handle flow control. This is done using @code{set-input-mode}. @item It sets up @code{keyboard-translate-table} to translate @kbd{C-\} and @@ -2061,10 +2109,11 @@ saved session to restore. For Emacs, this argument is @samp{--smid Emacs supports saving state by using a hook called @code{emacs-save-session-functions}. Each function in this hook is called when the session manager tells Emacs that the window system is -shutting down. The functions are called with the current buffer set -to a temporary buffer. Each function can use @code{insert} to add -Lisp code to this buffer. At the end, Emacs saves the buffer in a -file that another Emacs will later load in order to restart the saved session. +shutting down. The functions are called with no arguments and with the +current buffer set to a temporary buffer. Each function can use +@code{insert} to add Lisp code to this buffer. At the end, Emacs +saves the buffer in a file that a subsequent Emacs invocation will +load in order to restart the saved session. If a function in @code{emacs-save-session-functions} returns non-@code{nil}, Emacs tells the session manager to cancel the -- cgit v1.2.3