This is Info file ../../info/lispref.info, produced by Makeinfo version 1.68 from the input file lispref.texi. INFO-DIR-SECTION XEmacs Editor START-INFO-DIR-ENTRY * Lispref: (lispref). XEmacs Lisp Reference Manual. END-INFO-DIR-ENTRY Edition History: GNU Emacs Lisp Reference Manual Second Edition (v2.01), May 1993 GNU Emacs Lisp Reference Manual Further Revised (v2.02), August 1993 Lucid Emacs Lisp Reference Manual (for 19.10) First Edition, March 1994 XEmacs Lisp Programmer's Manual (for 19.12) Second Edition, April 1995 GNU Emacs Lisp Reference Manual v2.4, June 1995 XEmacs Lisp Programmer's Manual (for 19.13) Third Edition, July 1995 XEmacs Lisp Reference Manual (for 19.14 and 20.0) v3.1, March 1996 XEmacs Lisp Reference Manual (for 19.15 and 20.1, 20.2, 20.3) v3.2, April, May, November 1997 XEmacs Lisp Reference Manual (for 21.0) v3.3, April 1998 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc. Copyright (C) 1994, 1995 Sun Microsystems, Inc. Copyright (C) 1995, 1996 Ben Wing. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English.  File: lispref.info, Node: System Interface, Next: X-Windows, Prev: Processes, Up: Top Operating System Interface ************************** This chapter is about starting and getting out of Emacs, access to values in the operating system environment, and terminal input, output, and flow control. *Note Building XEmacs::, for related information. See also *Note Display::, for additional operating system status information pertaining to the terminal and the screen. * Menu: * Starting Up:: Customizing XEmacs start-up processing. * Getting Out:: How exiting works (permanent or temporary). * System Environment:: Distinguish the name and kind of system. * User Identification:: Finding the name and user id of the user. * Time of Day:: Getting the current time. * Time Conversion:: Converting a time from numeric form to 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. * Flow Control:: How to turn output flow control on or off. * Batch Mode:: Running XEmacs without terminal interaction.  File: lispref.info, Node: Starting Up, Next: Getting Out, Up: System Interface Starting Up XEmacs ================== This section describes what XEmacs does when it is started, and how you can customize these actions. * Menu: * Start-up Summary:: Sequence of actions XEmacs performs at start-up. * Init File:: Details on reading the init file (`.emacs'). * Terminal-Specific:: How the terminal-specific Lisp file is read. * Command Line Arguments:: How command line arguments are processed, and how you can customize them.  File: lispref.info, Node: Start-up Summary, Next: Init File, Up: Starting Up Summary: Sequence of Actions at Start Up ---------------------------------------- The order of operations performed (in `startup.el') by XEmacs when it is started up is as follows: 1. It loads the initialization library for the window system, if you are using a window system. This library's name is `term/WINDOWSYSTEM-win.el'. 2. It processes the initial options. (Some of them are handled even earlier than this.) 3. It initializes the X window frame and faces, if appropriate. 4. It runs the normal hook `before-init-hook'. 5. It loads the library `site-start', unless the option `-no-site-file' was specified. The library's file name is usually `site-start.el'. 6. It loads the file `~/.emacs' unless `-q' was specified on the command line. (This is not done in `-batch' mode.) The `-u' option can specify the user name whose home directory should be used instead of `~'. 7. It loads the library `default' unless `inhibit-default-init' is non-`nil'. (This is not done in `-batch' mode or if `-q' was specified on the command line.) The library's file name is usually `default.el'. 8. It runs the normal hook `after-init-hook'. 9. It sets the major mode according to `initial-major-mode', provided the buffer `*scratch*' is still current and still in Fundamental mode. 10. It loads the terminal-specific Lisp file, if any, except when in batch mode or using a window system. 11. It displays the initial echo area message, unless you have suppressed that with `inhibit-startup-echo-area-message'. 12. It processes the action arguments from the command line. 13. It runs `term-setup-hook'. 14. It calls `frame-notice-user-settings', which modifies the parameters of the selected frame according to whatever the init files specify. 15. It runs `window-setup-hook'. *Note Terminal-Specific::. 16. It displays copyleft, nonwarranty, and basic use information, provided there were no remaining command line arguments (a few steps above) and the value of `inhibit-startup-message' is `nil'. - User Option: inhibit-startup-message This variable inhibits the initial startup messages (the nonwarranty, etc.). If it is non-`nil', then the messages are not printed. This variable exists so you can set it in your personal init file, once you are familiar with the contents of the startup message. Do not set this variable in the init file of a new user, or in a way that affects more than one user, because that would prevent new users from receiving the information they are supposed to see. - User Option: inhibit-startup-echo-area-message This variable controls the display of the startup echo area message. You can suppress the startup echo area message by adding text with this form to your `.emacs' file: (setq inhibit-startup-echo-area-message "YOUR-LOGIN-NAME") Simply setting `inhibit-startup-echo-area-message' to your login name is not sufficient to inhibit the message; Emacs explicitly checks whether `.emacs' contains an expression as shown above. Your login name must appear in the expression as a Lisp string constant. This way, you can easily inhibit the message for yourself if you wish, but thoughtless copying of your `.emacs' file will not inhibit the message for someone else.  File: lispref.info, Node: Init File, Next: Terminal-Specific, Prev: Start-up Summary, Up: Starting Up The Init File: `.emacs' ----------------------- When you start XEmacs, it normally attempts to load the file `.emacs' from your home directory. This file, if it exists, must contain Lisp code. It is called your "init file". The command line switches `-q' and `-u' affect the use of the init file; `-q' says not to load an init file, and `-u' says to load a specified user's init file instead of yours. *Note Entering XEmacs: (xemacs)Entering XEmacs. A site may have a "default init file", which is the library named `default.el'. XEmacs finds the `default.el' file through the standard search path for libraries (*note How Programs Do Loading::.). The XEmacs distribution does not come with this file; sites may provide one for local customizations. If the default init file exists, it is loaded whenever you start Emacs, except in batch mode or if `-q' is specified. But your own personal init file, if any, is loaded first; if it sets `inhibit-default-init' to a non-`nil' value, then XEmacs does not subsequently load the `default.el' file. Another file for site-customization is `site-start.el'. Emacs loads this *before* the user's init file. You can inhibit the loading of this file with the option `-no-site-file'. - Variable: site-run-file This variable specifies the site-customization file to load before the user's init file. Its normal value is `"site-start"'. If there is a great deal of code in your `.emacs' file, you should move it into another file named `SOMETHING.el', byte-compile it (*note Byte Compilation::.), and make your `.emacs' file load the other file using `load' (*note Loading::.). *Note Init File Examples: (xemacs)Init File Examples, for examples of how to make various commonly desired customizations in your `.emacs' file. - User Option: inhibit-default-init This variable prevents XEmacs from loading the default initialization library file for your session of XEmacs. If its value is non-`nil', then the default library is not loaded. The default value is `nil'. - Variable: before-init-hook - Variable: after-init-hook These two normal hooks are run just before, and just after, loading of the user's init file, `default.el', and/or `site-start.el'.  File: lispref.info, Node: Terminal-Specific, Next: Command Line Arguments, Prev: Init File, Up: Starting Up Terminal-Specific Initialization -------------------------------- Each terminal type can have its own Lisp library that XEmacs loads when run on that type of terminal. For a terminal type named TERMTYPE, the library is called `term/TERMTYPE'. XEmacs finds the file by searching the `load-path' directories as it does for other files, and trying the `.elc' and `.el' suffixes. Normally, terminal-specific Lisp library is located in `emacs/lisp/term', a subdirectory of the `emacs/lisp' directory in which most XEmacs Lisp libraries are kept. The library's name is constructed by concatenating the value of the variable `term-file-prefix' and the terminal type. Normally, `term-file-prefix' has the value `"term/"'; changing this is not recommended. The usual function of a terminal-specific library is to enable special keys to send sequences that XEmacs can recognize. It may also need to set or add to `function-key-map' if the Termcap entry does not specify all the terminal's function keys. *Note Terminal Input::. When the name of the terminal type contains a hyphen, only the part of the name before the first hyphen is significant in choosing the library name. Thus, terminal types `aaa-48' and `aaa-30-rv' both use the `term/aaa' library. If necessary, the library can evaluate `(getenv "TERM")' to find the full name of the terminal type. Your `.emacs' file can prevent the loading of the terminal-specific library by setting the variable `term-file-prefix' to `nil'. This feature is useful when experimenting with your own peculiar customizations. You can also arrange to override some of the actions of the terminal-specific library by setting the variable `term-setup-hook'. This is a normal hook which XEmacs runs using `run-hooks' at the end of XEmacs initialization, after loading both your `.emacs' file and any terminal-specific libraries. You can use this variable to define initializations for terminals that do not have their own libraries. *Note Hooks::. - Variable: term-file-prefix If the `term-file-prefix' variable is non-`nil', XEmacs loads a terminal-specific initialization file as follows: (load (concat term-file-prefix (getenv "TERM"))) You may set the `term-file-prefix' variable to `nil' in your `.emacs' file if you do not wish to load the terminal-initialization file. To do this, put the following in your `.emacs' file: `(setq term-file-prefix nil)'. - Variable: term-setup-hook This variable is a normal hook that XEmacs runs after loading your `.emacs' file, the default initialization file (if any) and the terminal-specific Lisp file. You can use `term-setup-hook' to override the definitions made by a terminal-specific file. - Variable: window-setup-hook This variable is a normal hook which XEmacs runs after loading your `.emacs' file and the default initialization file (if any), after loading terminal-specific Lisp code, and after running the hook `term-setup-hook'.  File: lispref.info, Node: Command Line Arguments, Prev: Terminal-Specific, Up: Starting Up Command Line Arguments ---------------------- You can use command line arguments to request various actions when you start XEmacs. Since you do not need to start XEmacs more than once per day, and will often leave your XEmacs session running longer than that, command line arguments are hardly ever used. As a practical matter, it is best to avoid making the habit of using them, since this habit would encourage you to kill and restart XEmacs unnecessarily often. These options exist for two reasons: to be compatible with other editors (for invocation by other programs) and to enable shell scripts to run specific Lisp programs. This section describes how Emacs processes command line arguments, and how you can customize them. - Function: command-line This function parses the command line that XEmacs was called with, processes it, loads the user's `.emacs' file and displays the startup messages. - Variable: command-line-processed The value of this variable is `t' once the command line has been processed. If you redump XEmacs by calling `dump-emacs', you may wish to set this variable to `nil' first in order to cause the new dumped XEmacs to process its new command line arguments. - Variable: command-switch-alist The value of this variable is an alist of user-defined command-line options and associated handler functions. This variable exists so you can add elements to it. A "command line option" is an argument on the command line of the form: -OPTION The elements of the `command-switch-alist' look like this: (OPTION . HANDLER-FUNCTION) The HANDLER-FUNCTION is called to handle OPTION and receives the option name as its sole argument. In some cases, the option is followed in the command line by an argument. In these cases, the HANDLER-FUNCTION can find all the remaining command-line arguments in the variable `command-line-args-left'. (The entire list of command-line arguments is in `command-line-args'.) The command line arguments are parsed by the `command-line-1' function in the `startup.el' file. See also *Note Command Line Switches and Arguments: (xemacs)Command Switches. - Variable: command-line-args The value of this variable is the list of command line arguments passed to XEmacs. - Variable: command-line-functions This variable's value is a list of functions for handling an unrecognized command-line argument. Each time the next argument to be processed has no special meaning, the functions in this list are called, in order of appearance, until one of them returns a non-`nil' value. These functions are called with no arguments. They can access the command-line argument under consideration through the variable `argi'. The remaining arguments (not including the current one) are in the variable `command-line-args-left'. When a function recognizes and processes the argument in `argi', it should return a non-`nil' value to say it has dealt with that argument. If it has also dealt with some of the following arguments, it can indicate that by deleting them from `command-line-args-left'. If all of these functions return `nil', then the argument is used as a file name to visit.  File: lispref.info, Node: Getting Out, Next: System Environment, Prev: Starting Up, Up: System Interface Getting out of XEmacs ===================== There are two ways to get out of XEmacs: you can kill the XEmacs job, which exits permanently, or you can suspend it, which permits you to reenter the XEmacs process later. As a practical matter, you seldom kill XEmacs--only when you are about to log out. Suspending is much more common. * Menu: * Killing XEmacs:: Exiting XEmacs irreversibly. * Suspending XEmacs:: Exiting XEmacs reversibly.  File: lispref.info, Node: Killing XEmacs, Next: Suspending XEmacs, Up: Getting Out Killing XEmacs -------------- Killing XEmacs means ending the execution of the XEmacs process. The parent process normally resumes control. The low-level primitive for killing XEmacs is `kill-emacs'. - Function: kill-emacs &optional EXIT-DATA This function exits the XEmacs process and kills it. If EXIT-DATA is an integer, then it is used as the exit status of the XEmacs process. (This is useful primarily in batch operation; see *Note Batch Mode::.) If EXIT-DATA is a string, its contents are stuffed into the terminal input buffer so that the shell (or whatever program next reads input) can read them. All the information in the XEmacs process, aside from files that have been saved, is lost when the XEmacs is killed. Because killing XEmacs inadvertently can lose a lot of work, XEmacs queries for confirmation before actually terminating if you have buffers that need saving or subprocesses that are running. This is done in the function `save-buffers-kill-emacs'. - Variable: kill-emacs-query-functions After asking the standard questions, `save-buffers-kill-emacs' calls the functions in the list `kill-buffer-query-functions', in order of appearance, with no arguments. These functions can ask for additional confirmation from the user. If any of them returns non-`nil', XEmacs is not killed. - Variable: kill-emacs-hook This variable is a normal hook; once `save-buffers-kill-emacs' is finished with all file saving and confirmation, it runs the functions in this hook.  File: lispref.info, Node: Suspending XEmacs, Prev: Killing XEmacs, Up: Getting Out Suspending XEmacs ----------------- "Suspending XEmacs" means stopping XEmacs temporarily and returning control to its superior process, which is usually the shell. This allows you to resume editing later in the same XEmacs process, with the same buffers, the same kill ring, the same undo history, and so on. To resume XEmacs, use the appropriate command in the parent shell--most likely `fg'. Some operating systems do not support suspension of jobs; on these systems, "suspension" actually creates a new shell temporarily as a subprocess of XEmacs. Then you would exit the shell to return to XEmacs. Suspension is not useful with window systems such as X, because the XEmacs job may not have a parent that can resume it again, and in any case you can give input to some other job such as a shell merely by moving to a different window. Therefore, suspending is not allowed when XEmacs is an X client. - Function: suspend-emacs STRING This function stops XEmacs and returns control to the superior process. If and when the superior process resumes XEmacs, `suspend-emacs' returns `nil' to its caller in Lisp. If STRING is non-`nil', its characters are sent to be read as terminal input by XEmacs's superior shell. The characters in STRING are not echoed by the superior shell; only the results appear. Before suspending, `suspend-emacs' runs the normal hook `suspend-hook'. In Emacs version 18, `suspend-hook' was not a normal hook; its value was a single function, and if its value was non-`nil', then `suspend-emacs' returned immediately without actually suspending anything. After the user resumes XEmacs, `suspend-emacs' runs the normal hook `suspend-resume-hook'. *Note Hooks::. The next redisplay after resumption will redraw the entire screen, unless the variable `no-redraw-on-reenter' is non-`nil' (*note Refresh Screen::.). In the following example, note that `pwd' is not echoed after XEmacs is suspended. But it is read and executed by the shell. (suspend-emacs) => nil (add-hook 'suspend-hook (function (lambda () (or (y-or-n-p "Really suspend? ") (error "Suspend cancelled"))))) => (lambda nil (or (y-or-n-p "Really suspend? ") (error "Suspend cancelled"))) (add-hook 'suspend-resume-hook (function (lambda () (message "Resumed!")))) => (lambda nil (message "Resumed!")) (suspend-emacs "pwd") => nil ---------- Buffer: Minibuffer ---------- Really suspend? y ---------- Buffer: Minibuffer ---------- ---------- Parent Shell ---------- lewis@slug[23] % /user/lewis/manual lewis@slug[24] % fg ---------- Echo Area ---------- Resumed! - Variable: suspend-hook This variable is a normal hook run before suspending. - Variable: suspend-resume-hook This variable is a normal hook run after suspending.  File: lispref.info, Node: System Environment, Next: User Identification, Prev: Getting Out, Up: System Interface Operating System Environment ============================ XEmacs provides access to variables in the operating system environment through various functions. These variables include the name of the system, the user's UID, and so on. - Variable: system-type The value of this variable is a symbol indicating the type of operating system XEmacs is operating on. Here is a table of the possible values: `aix-v3' AIX. `berkeley-unix' Berkeley BSD. `dgux' Data General DGUX operating system. `gnu' A GNU system using the GNU HURD and Mach. `hpux' Hewlett-Packard HPUX operating system. `irix' Silicon Graphics Irix system. `linux' A GNU system using the Linux kernel. `ms-dos' Microsoft MS-DOS "operating system." `next-mach' NeXT Mach-based system. `rtu' Masscomp RTU, UCB universe. `unisoft-unix' UniSoft UniPlus. `usg-unix-v' AT&T System V. `vax-vms' VAX VMS. `windows-nt' Microsoft windows NT. `xenix' SCO Xenix 386. 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 `system-configuration' to distinguish between different operating systems. - Variable: system-configuration This variable holds the three-part configuration name for the hardware/software configuration of your system, as a string. The convenient way to test parts of this string is with `string-match'. - Function: system-name This function returns the name of the machine you are running on. (system-name) => "prep.ai.mit.edu" The symbol `system-name' is a variable as well as a function. In fact, the function returns whatever value the variable `system-name' currently holds. Thus, you can set the variable `system-name' in case Emacs is confused about the name of your system. The variable is also useful for constructing frame titles (*note Frame Titles::.). - Variable: mail-host-address If this variable is non-`nil', it is used instead of `system-name' for purposes of generating email addresses. For example, it is used when constructing the default value of `user-mail-address'. *Note User Identification::. (Since this is done when XEmacs starts up, the value actually used is the one saved when XEmacs was dumped. *Note Building XEmacs::.) - Function: getenv VAR This function returns the value of the environment variable VAR, as a string. Within XEmacs, the environment variable values are kept in the Lisp variable `process-environment'. (getenv "USER") => "lewis" lewis@slug[10] % printenv PATH=.:/user/lewis/bin:/usr/bin:/usr/local/bin USER=lewis TERM=ibmapa16 SHELL=/bin/csh HOME=/user/lewis - Command: setenv VARIABLE VALUE This command sets the value of the environment variable named VARIABLE to VALUE. Both arguments should be strings. This function works by modifying `process-environment'; binding that variable with `let' is also reasonable practice. - Variable: process-environment This variable is a list of strings, each describing one environment variable. The functions `getenv' and `setenv' work by means of this variable. process-environment => ("l=/usr/stanford/lib/gnuemacs/lisp" "PATH=.:/user/lewis/bin:/usr/class:/nfsusr/local/bin" "USER=lewis" "TERM=ibmapa16" "SHELL=/bin/csh" "HOME=/user/lewis") - Variable: 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 `":"' for Unix and GNU systems, and `";"' for MS-DOS and Windows NT. - Variable: 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. - Variable: invocation-directory This variable holds the directory from which the Emacs executable was invoked, or perhaps `nil' if that directory cannot be determined. - Variable: installation-directory If non-`nil', this is a directory within which to look for the `lib-src' and `etc' subdirectories. This is non-`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. - Function: load-average &optional USE-FLOATS This function returns a list of the current 1-minute, 5-minute and 15-minute load averages. The values are integers that are 100 times the system load averages. (The load averages indicate the number of processes trying to run.) When USE-FLOATS is non-`nil', floats will be returned instead of integers. These floats are not multiplied by 100. (load-average) => (169 158 164) (load-average t) => (1.69921875 1.58984375 1.640625) lewis@rocky[5] % uptime 8:06pm up 16 day(s), 21:57, 40 users, load average: 1.68, 1.59, 1.64 If the 5-minute or 15-minute load averages are not available, return a shortened list, containing only those averages which are available. On some systems, this function may require special privileges to run, or it may be unimplemented for the particular system type. In that case, the function will signal an error. - Function: emacs-pid This function returns the process ID of the Emacs process. - Function: 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, SETP, is `t' or `nil', indicating whether the privilege is to be turned on or off. Its default is `nil'. The function returns `t' if successful, `nil' otherwise. If the third argument, GETPRV, is non-`nil', `setprv' does not change the privilege, but returns `t' or `nil' indicating whether the privilege is currently enabled.  File: lispref.info, Node: User Identification, Next: Time of Day, Prev: System Environment, Up: System Interface User Identification =================== - Variable: user-mail-address This holds the nominal email address of the user who is using Emacs. When Emacs starts up, it computes a default value that is usually right, but users often set this themselves when the default value is not right. - Function: user-login-name &optional UID If you don't specify UID, this function returns the name under which the user is logged in. If the environment variable `LOGNAME' is set, that value is used. Otherwise, if the environment variable `USER' is set, that value is used. Otherwise, the value is based on the effective UID, not the real UID. If you specify UID, the value is the user name that corresponds to UID (which should be an integer). (user-login-name) => "lewis" - Function: user-real-login-name This function returns the user name corresponding to Emacs's real UID. This ignores the effective UID and ignores the environment variables `LOGNAME' and `USER'. - Variable: user-full-name This variable holds the name of the user running this Emacs. It is initialized at startup time from the value of `NAME' environment variable. You can change the value of this variable to alter the result of the `user-full-name' function. - Function: user-full-name &optional USER This function returns the full name of USER. If USER is `nil', it defaults to the user running this Emacs. In that case, the value of `user-full-name' variable, if non-`nil', will be used. If USER is specified explicitly, `user-full-name' variable is ignored. (user-full-name) => "Hrvoje Niksic" (setq user-full-name "Hrvoje \"Niksa\" Niksic") (user-full-name) => "Hrvoje \"Niksa\" Niksic" (user-full-name "hniksic") => "Hrvoje Niksic" The symbols `user-login-name', `user-real-login-name' and `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 (*note Frame Titles::.). - Function: user-real-uid This function returns the real UID of the user. (user-real-uid) => 19 - Function: user-uid This function returns the effective UID of the user. - Function: user-home-directory This function returns the "`HOME'" directory of the user, and is intended to replace occurrences of "`(getenv "HOME")'". Under Unix systems, the following is done: 1. Return the value of "`(getenv "HOME")'", if set. 2. Return "/", as a fallback, but issue a warning. (Future versions of XEmacs will also attempt to lookup the `HOME' directory via `getpwent()', but this has not yet been implemented.) Under MS Windows, this is done: 1. Return the value of "`(getenv "HOME")'", if set. 2. If the environment variables `HOMEDRIVE' and `HOMEDIR' are both set, return the concatenation (the following description uses MS Windows environment variable substitution syntax): `%HOMEDRIVE%%HOMEDIR%'. 3. Return "C:\", as a fallback, but issue a warning.  File: lispref.info, Node: Time of Day, Next: Time Conversion, Prev: User Identification, Up: System Interface Time of Day =========== This section explains how to determine the current time and the time zone. - Function: current-time-string &optional TIME-VALUE 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 `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. The argument 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 `current-time' (see below) and from `file-attributes' (*note File Attributes::.). (current-time-string) => "Wed Oct 14 22:21:05 1987" - Function: current-time This function returns the system's time value as a list of three integers: `(HIGH LOW MICROSEC)'. The integers HIGH and LOW combine to give the number of seconds since 0:00 January 1, 1970, which is HIGH * 2**16 + LOW. The third element, 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 `file-attributes'. *Note File Attributes::. - Function: 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 `(OFFSET NAME)'. Here 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, 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 `nil'. The argument 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 `current-time' (see above) and from `file-attributes' (*note File Attributes::.).  File: lispref.info, Node: Time Conversion, Next: Timers, Prev: Time of Day, Up: System Interface 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 `current-time' (*note Time of Day::.) and `file-attributes' (*note File Attributes::.). - Function: format-time-string FORMAT-STRING &optional TIME This function converts TIME to a string according to FORMAT-STRING. If TIME is omitted, it defaults to the current time. The argument FORMAT-STRING may contain `%'-sequences which say to substitute parts of the time. Here is a table of what the `%'-sequences mean: `%a' This stands for the abbreviated name of the day of week. `%A' This stands for the full name of the day of week. `%b' This stands for the abbreviated name of the month. `%B' This stands for the full name of the month. `%c' This is a synonym for `%x %X'. `%C' This has a locale-specific meaning. In the default locale (named C), it is equivalent to `%A, %B %e, %Y'. `%d' This stands for the day of month, zero-padded. `%D' This is a synonym for `%m/%d/%y'. `%e' This stands for the day of month, blank-padded. `%h' This is a synonym for `%b'. `%H' This stands for the hour (00-23). `%I' This stands for the hour (00-12). `%j' This stands for the day of the year (001-366). `%k' This stands for the hour (0-23), blank padded. `%l' This stands for the hour (1-12), blank padded. `%m' This stands for the month (01-12). `%M' This stands for the minute (00-59). `%n' This stands for a newline. `%p' This stands for `AM' or `PM', as appropriate. `%r' This is a synonym for `%I:%M:%S %p'. `%R' This is a synonym for `%H:%M'. `%S' This stands for the seconds (00-60). `%t' This stands for a tab character. `%T' This is a synonym for `%H:%M:%S'. `%U' This stands for the week of the year (01-52), assuming that weeks start on Sunday. `%w' This stands for the numeric day of week (0-6). Sunday is day 0. `%W' This stands for the week of the year (01-52), assuming that weeks start on Monday. `%x' This has a locale-specific meaning. In the default locale (named C), it is equivalent to `%D'. `%X' This has a locale-specific meaning. In the default locale (named C), it is equivalent to `%T'. `%y' This stands for the year without century (00-99). `%Y' This stands for the year with century. `%Z' This stands for the time zone abbreviation. - Function: decode-time TIME This function converts a time value into calendrical information. The return value is a list of nine elements, as follows: (SECONDS MINUTES HOUR DAY MONTH YEAR DOW DST ZONE) Here is what the elements mean: SEC The number of seconds past the minute, as an integer between 0 and 59. MINUTE The number of minutes past the hour, as an integer between 0 and 59. HOUR The hour of the day, as an integer between 0 and 23. DAY The day of the month, as an integer between 1 and 31. MONTH The month of the year, as an integer between 1 and 12. YEAR The year, an integer typically greater than 1900. DOW The day of week, as an integer between 0 and 6, where 0 stands for Sunday. DST `t' if daylight savings time is effect, otherwise `nil'. ZONE An integer indicating the time zone, as the number of seconds east of Greenwich. Note that Common Lisp has different meanings for DOW and ZONE. - Function: encode-time SECONDS MINUTES HOUR DAY MONTH YEAR &optional ZONE This function is the inverse of `decode-time'. It converts seven items of calendrical data into a time value. For the meanings of the arguments, see the table above under `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 `encode-time'. The optional argument 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 `current-time-zone') or an integer (as you would get from `decode-time'). The specified zone is used without any further alteration for daylight savings time.  File: lispref.info, Node: Timers, Next: Terminal Input, Prev: Time Conversion, Up: System Interface Timers for Delayed Execution ============================ You can set up a timer to call a function at a specified future time. - Function: add-timeout SECS FUNCTION OBJECT &optional RESIGNAL This function adds a timeout, to be signaled after the timeout period has elapsed. SECS is a number of seconds, expressed as an integer or a float. FUNCTION will be called after that many seconds have elapsed, with one argument, the given OBJECT. If the optional RESIGNAL argument is provided, then after this timeout expires, `add-timeout' will automatically be called again with RESIGNAL as the first argument. This function returns an object which is the "id" of this particular timeout. You can pass that object to `disable-timeout' to turn off the timeout before it has been signalled. The number of seconds may be expressed as a floating-point number, in which case some fractional part of a second will be used. Caveat: the usable timeout granularity will vary from system to system. Adding a timeout causes a timeout event to be returned by `next-event', and the function will be invoked by `dispatch-event', so if XEmacs is in a tight loop, the function will not be invoked until the next call to sit-for or until the return to top-level (the same is true of process filters). WARNING: if you are thinking of calling add-timeout from inside of a callback function as a way of resignalling a timeout, think again. There is a race condition. That's why the RESIGNAL argument exists. (NOTE: In FSF Emacs, this function is called `run-at-time' and has different semantics.) - Function: disable-timeout ID Cancel the requested action for ID, which should be a value previously returned by `add-timeout'. This cancels the effect of that call to `add-timeout'; the arrival of the specified time will not cause anything special to happen. (NOTE: In FSF Emacs, this function is called `cancel-timer'.)  File: lispref.info, Node: Terminal Input, Next: Terminal Output, Prev: Timers, Up: System Interface Terminal Input ============== This section describes functions and variables for recording or manipulating terminal input. See *Note 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.  File: lispref.info, Node: Input Modes, Next: Translating Input, Up: Terminal Input Input Modes ----------- - Function: set-input-mode INTERRUPT FLOW META QUIT-CHAR This function sets the mode for reading keyboard input. If INTERRUPT is non-null, then XEmacs uses input interrupts. If it is `nil', then it uses CBREAK mode. When XEmacs communicates directly with X, it ignores this argument and uses interrupts if that is the way it knows how to communicate. If FLOW is non-`nil', then XEmacs uses XON/XOFF (`C-q', `C-s') flow control for output to the terminal. This has no effect except in CBREAK mode. *Note Flow Control::. The default setting is system dependent. Some systems always use CBREAK mode regardless of what is specified. The argument META controls support for input character codes above 127. If META is `t', XEmacs converts characters with the 8th bit set into Meta characters. If META is `nil', XEmacs disregards the 8th bit; this is necessary when the terminal uses it as a parity bit. If META is neither `t' nor `nil', XEmacs uses all 8 bits of input unchanged. This is good for terminals using European 8-bit character sets. If QUIT-CHAR is non-`nil', it specifies the character to use for quitting. Normally this character is `C-g'. *Note Quitting::. The `current-input-mode' function returns the input mode settings XEmacs is currently using. - Function: current-input-mode This function returns current mode for reading keyboard input. It returns a list, corresponding to the arguments of `set-input-mode', of the form `(INTERRUPT FLOW META QUIT)' in which: INTERRUPT is non-`nil' when XEmacs is using interrupt-driven input. If `nil', Emacs is using CBREAK mode. FLOW is non-`nil' if XEmacs uses XON/XOFF (`C-q', `C-s') flow control for output to the terminal. This value has no effect unless INTERRUPT is non-`nil'. META is `t' if XEmacs treats the eighth bit of input characters as the meta bit; `nil' means XEmacs clears the eighth bit of every input character; any other value means XEmacs uses all eight bits as the basic character code. QUIT is the character XEmacs currently uses for quitting, usually `C-g'.  File: lispref.info, Node: Translating Input, Next: Recording Input, Prev: Input Modes, Up: Terminal Input Translating Input Events ------------------------ This section describes features for translating input events into other input events before they become part of key sequences. - Variable: function-key-map This variable holds a keymap that describes the character sequences sent by function keys on an ordinary character terminal. This keymap uses the same data structure as other keymaps, but is used differently: it specifies translations to make while reading events. If `function-key-map' "binds" a key sequence K to a vector V, then when K appears as a subsequence *anywhere* in a key sequence, it is replaced with the events in V. For example, VT100 terminals send ` O P' when the keypad PF1 key is pressed. Therefore, we want XEmacs to translate that sequence of events into the single event `pf1'. We accomplish this by "binding" ` O P' to `[pf1]' in `function-key-map', when using a VT100. Thus, typing `C-c ' sends the character sequence `C-c O P'; later the function `read-key-sequence' translates this back into `C-c ', which it returns as the vector `[?\C-c pf1]'. Entries in `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. The value of `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. XEmacs comes with terminal-specific files for many common terminals; their main purpose is to make entries in `function-key-map' beyond those that can be deduced from Termcap and Terminfo. *Note Terminal-Specific::. Emacs versions 18 and earlier used totally different means of detecting the character sequences that represent function keys. - Variable: key-translation-map This variable is another keymap used just like `function-key-map' to translate input events into other events. It differs from `function-key-map' in two ways: * `key-translation-map' goes to work after `function-key-map' is finished; it receives the results of translation by `function-key-map'. * `key-translation-map' overrides actual key bindings. The intent of `key-translation-map' is for users to map one character set to another, including ordinary characters normally bound to `self-insert-command'. You can use `function-key-map' or `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 `read-key-sequence'--or `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 `C-c h' to turn the character that follows into a Hyper character: (defun hyperify (prompt) (let ((e (read-event))) (vector (if (numberp e) (logior (lsh 1 20) 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)))) (if (symbolp e) symbol (cons symbol (cdr e))))) (define-key function-key-map "\C-ch" 'hyperify) The `iso-transl' library uses this feature to provide a way of inputting non-ASCII Latin-1 characters.  File: lispref.info, Node: Recording Input, Prev: Translating Input, Up: Terminal Input Recording Input --------------- - Function: recent-keys &optional NUMBER This function returns a vector containing recent input events from the keyboard or mouse. By default, 100 events are recorded, which is how many `recent-keys' returns. All input events are included, whether or 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 that invoked the macros.) If NUMBER is specified, not more than NUMBER events will be returned. You may change the number of stored events using `set-recent-keys-ring-size'. - Function: recent-keys-ring-size This function returns the number of recent events stored internally. This is also the maximum number of events `recent-keys' can return. By default, 100 events are stored. - Function: set-recent-keys-ring-size SIZE This function changes the number of events stored by XEmacs and returned by `recent-keys'. For example, `(set-recent-keys-ring-size 250)' will make XEmacs remember last 250 events and will make `recent-keys' return last 250 events by default. - Command: open-dribble-file FILENAME This function opens a "dribble file" named 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 `<...>'. You close the dribble file by calling this function with an argument of `nil'. This function is normally used to record the input necessary to trigger an XEmacs bug, for the sake of a bug report. (open-dribble-file "~/dribble") => nil See also the `open-termscript' function (*note Terminal Output::.).