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26. Reading Mail

XEmacs provides several mail-reading packages. Each one comes with its own manual, which is included in each package.

The recommended mail-reading package for new users is VM. VM works with standard Unix-mail-format folders and was designed as a replacement for the older Rmail.

XEmacs also provides a sophisticated and comfortable front-end to the MH mail-processing system, called `MH-E'. Unlike in other mail programs, folders in MH are stored as file-system directories, with each message occupying one (numbered) file. This facilitates working with mail using shell commands, and many other features of MH are also designed to integrate well with the shell and with shell scripts. Keep in mind, however, that in order to use MH-E you must have the MH mail-processing system installed on your computer.

The Everything including the kitchen sink package `Gnus' is also available as an XEmacs package. Gnus also handles Usenet articles as well as mail.

`MEW' (Messaging in the Emacs World) is another mail-reading package available for XEmacs.

Finally, XEmacs provides the Rmail package. Rmail is (currently) the only mail reading package distributed with FSF GNU Emacs, and is powerful in its own right. However, it stores mail folders in a special format called `Babyl', that is incompatible with all other frequently-used mail programs. A utility program is provided for converting Babyl folders to standard Unix-mail format; however, unless you already have mail in Babyl-format folders, you should consider using Gnus, VM, or MH-E instead.


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26.1 Calendar Mode and the Diary

Emacs provides the functions of a desk calendar, with a diary of planned or past events. To enter the calendar, type M-x calendar; this displays a three-month calendar centered on the current month, with point on the current date. With a numeric argument, as in C-u M-x calendar, it prompts you for the month and year to be the center of the three-month calendar. The calendar uses its own buffer, whose major mode is Calendar mode.

Button2 in the calendar brings up a menu of operations on a particular date; Buttons3 brings up a menu of commonly used calendar features that are independent of any particular date. To exit the calendar, type q. See section `Calendar' in The XEmacs Lisp Reference Manual, for customization information about the calendar and diary.

26.1.1 Movement in the Calendar  Moving through the calendar; selecting a date.
26.1.2 Scrolling the Calendar through Time  Bringing earlier or later months onto the screen.
26.1.3 The Mark and the Region  Remembering dates, the mark ring.
26.1.4 Miscellaneous Calendar Commands  Exiting or recomputing the calendar.
26.2 LaTeX Calendar  Print a calendar using LaTeX.
26.2.1 Holidays  Displaying dates of holidays.
26.2.2 Times of Sunrise and Sunset  Displaying local times of sunrise and sunset.
26.2.3 Phases of the Moon  Displaying phases of the moon.
26.2.4 Conversion To and From Other Calendars  Converting dates to other calendar systems.
26.5.2 The Diary  Displaying events from your diary.
26.5.8 Customizing the Calendar and Diary  Altering the behavior of the features above.


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26.1.1 Movement in the Calendar

Calendar mode lets you move through the calendar in logical units of time such as days, weeks, months, and years. If you move outside the three months originally displayed, the calendar display "scrolls" automatically through time to make the selected date visible. Moving to a date lets you view its holidays or diary entries, or convert it to other calendars; moving longer time periods is also useful simply to scroll the calendar.

26.1.1.1 Motion by Integral Days, Weeks, Months, Years  Moving by days, weeks, months, and years.
26.1.1.2 Beginning or End of Week, Month or Year  Moving to start/end of weeks, months, and years.
26.1.1.3 Particular Dates  Moving to the current date or another specific date.


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26.1.1.1 Motion by Integral Days, Weeks, Months, Years

The commands for movement in the calendar buffer parallel the commands for movement in text. You can move forward and backward by days, weeks, months, and years.

C-f
Move point one day forward (calendar-forward-day).
C-b
Move point one day backward (calendar-backward-day).
C-n
Move point one week forward (calendar-forward-week).
C-p
Move point one week backward (calendar-backward-week).
M-}
Move point one month forward (calendar-forward-month).
M-{
Move point one month backward (calendar-backward-month).
C-x ]
Move point one year forward (calendar-forward-year).
C-x [
Move point one year backward (calendar-backward-year).

The day and week commands are natural analogues of the usual Emacs commands for moving by characters and by lines. Just as C-n usually moves to the same column in the following line, in Calendar mode it moves to the same day in the following week. And C-p moves to the same day in the previous week.

The arrow keys are equivalent to C-f, C-b, C-n and C-p, just as they normally are in other modes.

The commands for motion by months and years work like those for weeks, but move a larger distance. The month commands M-} and M-{ move forward or backward by an entire month's time. The year commands C-x ] and C-x [ move forward or backward a whole year.

The easiest way to remember these commands is to consider months and years analogous to paragraphs and pages of text, respectively. But the commands themselves are not quite analogous. The ordinary Emacs paragraph commands move to the beginning or end of a paragraph, whereas these month and year commands move by an entire month or an entire year, which usually involves skipping across the end of a month or year.

All these commands accept a numeric argument as a repeat count. For convenience, the digit keys and the minus sign specify numeric arguments in Calendar mode even without the Meta modifier. For example, 100 C-f moves point 100 days forward from its present location.


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26.1.1.2 Beginning or End of Week, Month or Year

A week (or month, or year) is not just a quantity of days; we think of weeks (months, years) as starting on particular dates. So Calendar mode provides commands to move to the beginning or end of a week, month or year:

C-a
Move point to start of week (calendar-beginning-of-week).
C-e
Move point to end of week (calendar-end-of-week).
M-a
Move point to start of month (calendar-beginning-of-month).
M-e
Move point to end of month (calendar-end-of-month).
M-<
Move point to start of year (calendar-beginning-of-year).
M->
Move point to end of year (calendar-end-of-year).

These commands also take numeric arguments as repeat counts, with the repeat count indicating how many weeks, months, or years to move backward or forward.

By default, weeks begin on Sunday. To make them begin on Monday instead, set the variable calendar-week-start-day to 1.


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26.1.1.3 Particular Dates

Calendar mode provides commands for moving to a particular date specified in various ways.

g d
Move point to specified date (calendar-goto-date).
o
Center calendar around specified month (calendar-other-month).
.
Move point to today's date (calendar-goto-today).

g d (calendar-goto-date) prompts for a year, a month, and a day of the month, and then moves to that date. Because the calendar includes all dates from the beginning of the current era, you must type the year in its entirety; that is, type `1990', not `90'.

o (calendar-other-month) prompts for a month and year, then centers the three-month calendar around that month.

You can return to today's date with . (calendar-goto-today).


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26.1.2 Scrolling the Calendar through Time

The calendar display scrolls automatically through time when you move out of the visible portion. You can also scroll it manually. Imagine that the calendar window contains a long strip of paper with the months on it. Scrolling it means moving the strip so that new months become visible in the window.

C-x <
Scroll calendar one month forward (scroll-calendar-left).
C-x >
Scroll calendar one month backward (scroll-calendar-right).
C-v
NEXT
Scroll calendar three months forward (scroll-calendar-left-three-months).
M-v
PRIOR
Scroll calendar three months backward (scroll-calendar-right-three-months).

The most basic calendar scroll commands scroll by one month at a time. This means that there are two months of overlap between the display before the command and the display after. C-x < scrolls the calendar contents one month to the left; that is, it moves the display forward in time. C-x > scrolls the contents to the right, which moves backwards in time.

The commands C-v and M-v scroll the calendar by an entire "screenful"---three months--in analogy with the usual meaning of these commands. C-v makes later dates visible and M-v makes earlier dates visible. These commands take a numeric argument as a repeat count; in particular, since C-u multiplies the next command by four, typing C-u C-v scrolls the calendar forward by a year and typing C-u M-v scrolls the calendar backward by a year.

The function keys NEXT and PRIOR are equivalent to C-v and M-v, just as they are in other modes.


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26.1.3 The Mark and the Region

The concept of the mark applies to the calendar just as to any other buffer, but it marks a date, not a position in the buffer. The region consists of the days between the mark and point (including the starting and stopping dates).

C-SPC
Set the mark to today's date (calendar-set-mark).
C-@
The same.
C-x C-x
Interchange mark and point (calendar-exchange-point-and-mark).
M-=
Display the number of days in the current region (calendar-count-days-region).

You set the mark in the calendar, as in any other buffer, by using C-@ or C-SPC (calendar-set-mark). You return to the marked date with the command C-x C-x (calendar-exchange-point-and-mark) which puts the mark where point was and point where mark was. The calendar is scrolled as necessary, if the marked date was not visible on the screen. This does not change the extent of the region.

To determine the number of days in the region, type M-= (calendar-count-days-region). The numbers of days printed is inclusive; that is, it includes the days specified by mark and point.

The main use of the mark in the calendar is to remember dates that you may want to go back to. To make this feature more useful, the mark ring (see section 9.1.4 The Mark Ring) operates exactly as in other buffers: Emacs remembers 16 previous locations of the mark. To return to a marked date, type C-u C-SPC (or C-u C-@); this is the command calendar-set-mark given a numeric argument. It moves point to where the mark was, restores the mark from the ring of former marks, and stores the previous point at the end of the mark ring. So, repeated use of this command moves point through all the old marks on the ring, one by one.


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26.1.4 Miscellaneous Calendar Commands

p d
Display day-in-year (calendar-print-day-of-year).
?
Briefly describe calendar commands (describe-calendar-mode).
C-c C-l
Regenerate the calendar window (redraw-calendar).
SPC
Scroll the next window (scroll-other-window).
q
Exit from calendar (exit-calendar).

If you want to know how many days have elapsed since the start of the year, or the number of days remaining in the year, type the p d command (calendar-print-day-of-year). This displays both of those numbers in the echo area.

To display a brief description of the calendar commands, type ? (describe-calendar-mode). For a fuller description, type C-h m.

You can use SPC (scroll-other-window) to scroll the other window. This is handy when you display a list of holidays or diary entries in another window.

If the calendar window text gets corrupted, type C-c C-l (redraw-calendar) to redraw it. (This can only happen if you use non-Calendar-mode editing commands.)

In Calendar mode, you can use SPC (scroll-other-window) to scroll the other window. This is handy when you display a list of holidays or diary entries in another window.

To exit from the calendar, type q (exit-calendar). This buries all buffers related to the calendar, selecting other buffers. (If a frame contains a dedicated calendar window, exiting from the calendar iconifies that frame.)


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26.2 LaTeX Calendar

The Calendar LaTeX commands produce a buffer of LaTeX code that prints as a calendar. Depending on the command you use, the printed calendar covers the day, week, month or year that point is in.

t m
Generate a one-month calendar (cal-tex-cursor-month).
t M
Generate a sideways-printing one-month calendar (cal-tex-cursor-month-landscape).
t d
Generate a one-day calendar (cal-tex-cursor-day).
t w 1
Generate a one-page calendar for one week (cal-tex-cursor-week).
t w 2
Generate a two-page calendar for one week (cal-tex-cursor-week2).
t w 3
Generate an ISO-style calendar for one week (cal-tex-cursor-week-iso).
t w 4
Generate a calendar for one Monday-starting week (cal-tex-cursor-week-monday).
t f w
Generate a Filofax-style two-weeks-at-a-glance calendar (cal-tex-cursor-filofax-2week).
t f W
Generate a Filofax-style one-week-at-a-glance calendar (cal-tex-cursor-filofax-week).
t y
Generate a calendar for one year (cal-tex-cursor-year).
t Y
Generate a sideways-printing calendar for one year (cal-tex-cursor-year-landscape).
t f y
Generate a Filofax-style calendar for one year (cal-tex-cursor-filofax-year).

Some of these commands print the calendar sideways (in "landscape mode"), so it can be wider than it is long. Some of them use Filofax paper size (3.75in x 6.75in). All of these commands accept a prefix argument which specifies how many days, weeks, months or years to print (starting always with the selected one).

If the variable cal-tex-holidays is non-nil (the default), then the printed calendars show the holidays in calendar-holidays. If the variable cal-tex-diary is non-nil (the default is nil), diary entries are included also (in weekly and monthly calendars only).


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26.2.1 Holidays

The Emacs calendar knows about all major and many minor holidays, and can display them.

h
Display holidays for the selected date (calendar-cursor-holidays).
Button2 Holidays
Display any holidays for the date you click on.
x
Mark holidays in the calendar window (mark-calendar-holidays).
u
Unmark calendar window (calendar-unmark).
a
List all holidays for the displayed three months in another window (list-calendar-holidays).
M-x holidays
List all holidays for three months around today's date in another window.
M-x list-holidays
List holidays in another window for a specified range of years.

To see if any holidays fall on a given date, position point on that date in the calendar window and use the h command. Alternatively, click on that date with Button2 and then choose Holidays from the menu that appears. Either way, this displays the holidays for that date, in the echo area if they fit there, otherwise in a separate window.

To view the distribution of holidays for all the dates shown in the calendar, use the x command. This displays the dates that are holidays in a different face (or places a `*' after these dates, if display with multiple faces is not available). The command applies both to the currently visible months and to other months that subsequently become visible by scrolling. To turn marking off and erase the current marks, type u, which also erases any diary marks (see section 26.5.2 The Diary).

To get even more detailed information, use the a command, which displays a separate buffer containing a list of all holidays in the current three-month range. You can use SPC in the calendar window to scroll that list.

The command M-x holidays displays the list of holidays for the current month and the preceding and succeeding months; this works even if you don't have a calendar window. If you want the list of holidays centered around a different month, use C-u M-x holidays, which prompts for the month and year.

The holidays known to Emacs include United States holidays and the major Christian, Jewish, and Islamic holidays; also the solstices and equinoxes.

The command M-x list-holidays displays the list of holidays for a range of years. This function asks you for the starting and stopping years, and allows you to choose all the holidays or one of several categories of holidays. You can use this command even if you don't have a calendar window.

The dates used by Emacs for holidays are based on current practice, not historical fact. Historically, for instance, the start of daylight savings time and even its existence have varied from year to year, but present United States law mandates that daylight savings time begins on the first Sunday in April. When the daylight savings rules are set up for the United States, Emacs always uses the present definition, even though it is wrong for some prior years.


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26.2.2 Times of Sunrise and Sunset

Special calendar commands can tell you, to within a minute or two, the times of sunrise and sunset for any date.

S
Display times of sunrise and sunset for the selected date (calendar-sunrise-sunset).
Button2 Sunrise/Sunset
Display times of sunrise and sunset for the date you click on.
M-x sunrise-sunset
Display times of sunrise and sunset for today's date.
C-u M-x sunrise-sunset
Display times of sunrise and sunset for a specified date.

Within the calendar, to display the local times of sunrise and sunset in the echo area, move point to the date you want, and type S. Alternatively, click Button2 on the date, then choose Sunrise/Sunset from the menu that appears. The command M-x sunrise-sunset is available outside the calendar to display this information for today's date or a specified date. To specify a date other than today, use C-u M-x sunrise-sunset, which prompts for the year, month, and day.

You can display the times of sunrise and sunset for any location and any date with C-u C-u M-x sunrise-sunset. This asks you for a longitude, latitude, number of minutes difference from Coordinated Universal Time, and date, and then tells you the times of sunrise and sunset for that location on that date.

Because the times of sunrise and sunset depend on the location on earth, you need to tell Emacs your latitude, longitude, and location name before using these commands. Here is an example of what to set:

 
(setq calendar-latitude 40.1)
(setq calendar-longitude -88.2)
(setq calendar-location-name "Urbana, IL")

Use one decimal place in the values of calendar-latitude and calendar-longitude.

Your time zone also affects the local time of sunrise and sunset. Emacs usually gets time zone information from the operating system, but if these values are not what you want (or if the operating system does not supply them), you must set them yourself. Here is an example:

 
(setq calendar-time-zone -360)
(setq calendar-standard-time-zone-name "CST")
(setq calendar-daylight-time-zone-name "CDT")

The value of calendar-time-zone is the number of minutes difference between your local standard time and Coordinated Universal Time (Greenwich time). The values of calendar-standard-time-zone-name and calendar-daylight-time-zone-name are the abbreviations used in your time zone. Emacs displays the times of sunrise and sunset corrected for daylight savings time. See section 26.5.8.5 Daylight Savings Time, for how daylight savings time is determined.

As a user, you might find it convenient to set the calendar location variables for your usual physical location in your init file. And when you install Emacs on a machine, you can create a `default.el' file which sets them properly for the typical location of most users of that machine. See section 27.7 The Init File.


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26.2.3 Phases of the Moon

These calendar commands display the dates and times of the phases of the moon (new moon, first quarter, full moon, last quarter). This feature is useful for debugging problems that "depend on the phase of the moon."

M
Display the dates and times for all the quarters of the moon for the three-month period shown (calendar-phases-of-moon).
M-x phases-of-moon
Display dates and times of the quarters of the moon for three months around today's date.

Within the calendar, use the M command to display a separate buffer of the phases of the moon for the current three-month range. The dates and times listed are accurate to within a few minutes.

Outside the calendar, use the command M-x phases-of-moon to display the list of the phases of the moon for the current month and the preceding and succeeding months. For information about a different month, use C-u M-x phases-of-moon, which prompts for the month and year. The dates and times given for the phases of the moon are given in local time (corrected for daylight savings, when appropriate); but if the variable calendar-time-zone is void, Coordinated Universal Time (the Greenwich time zone) is used. See section 26.5.8.5 Daylight Savings Time.


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26.2.4 Conversion To and From Other Calendars

The Emacs calendar displayed is always the Gregorian calendar, sometimes called the "new style" calendar, which is used in most of the world today. However, this calendar did not exist before the sixteenth century and was not widely used before the eighteenth century; it did not fully displace the Julian calendar and gain universal acceptance until the early twentieth century. The Emacs calendar can display any month since January, year 1 of the current era, but the calendar displayed is the Gregorian, even for a date at which the Gregorian calendar did not exist.

While Emacs cannot display other calendars, it can convert dates to and from several other calendars.

26.3 Supported Calendar Systems  The calendars Emacs understands
(aside from Gregorian).
26.4 Converting To Other Calendars  Converting the selected date to various calendars.
26.5 Converting From Other Calendars  Moving to a date specified in another calendar.
26.5.1 Converting from the Mayan Calendar  Moving to a date specified in a Mayan calendar.

If you are interested in these calendars, you can convert dates one at a time. Put point on the desired date of the Gregorian calendar and press the appropriate keys. The p is a mnemonic for "print" since Emacs "prints' the equivalent date in the echo area.


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26.3 Supported Calendar Systems

The ISO commercial calendar is used largely in Europe.

The Julian calendar, named after Julius Caesar, was the one used in Europe throughout medieval times, and in many countries up until the nineteenth century.

Astronomers use a simple counting of days elapsed since noon, Monday, January 1, 4713 B.C. on the Julian calendar. The number of days elapsed is called the Julian day number or the Astronomical day number.

The Hebrew calendar is used by tradition in the Jewish religion. The Emacs calendar program uses the Hebrew calendar to determine the dates of Jewish holidays. Hebrew calendar dates begin and end at sunset.

The Islamic calendar is used in many predominantly Islamic countries. Emacs uses it to determine the dates of Islamic holidays. There is no universal agreement in the Islamic world about the calendar; Emacs uses a widely accepted version, but the precise dates of Islamic holidays often depend on proclamation by religious authorities, not on calculations. As a consequence, the actual dates of observance can vary slightly from the dates computed by Emacs. Islamic calendar dates begin and end at sunset.

The French Revolutionary calendar was created by the Jacobins after the 1789 revolution, to represent a more secular and nature-based view of the annual cycle, and to install a 10-day week in a rationalization measure similar to the metric system. The French government officially abandoned this calendar at the end of 1805.

The Maya of Central America used three separate, overlapping calendar systems, the long count, the tzolkin, and the haab. Emacs knows about all three of these calendars. Experts dispute the exact correlation between the Mayan calendar and our calendar; Emacs uses the Goodman-Martinez-Thompson correlation in its calculations.

The Copts use a calendar based on the ancient Egyptian solar calendar. Their calendar consists of twelve 30-day months followed by an extra five-day period. Once every fourth year they add a leap day to this extra period to make it six days. The Ethiopic calendar is identical in structure, but has different year numbers and month names.

The Persians use a solar calendar based on a design of Omar Khayyam. Their calendar consists of twelve months of which the first six have 31 days, the next five have 30 days, and the last has 29 in ordinary years and 30 in leap years. Leap years occur in a complicated pattern every four or five years.

The Chinese calendar is a complicated system of lunar months arranged into solar years. The years go in cycles of sixty, each year containing either twelve months in an ordinary year or thirteen months in a leap year; each month has either 29 or 30 days. Years, ordinary months, and days are named by combining one of ten "celestial stems" with one of twelve "terrestrial branches" for a total of sixty names that are repeated in a cycle of sixty.


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26.4 Converting To Other Calendars

The following commands describe the selected date (the date at point) in various other calendar systems:

Button2 Other Calendars
Display the date that you click on, expressed in various other calendars.
p c
Display ISO commercial calendar equivalent for selected day (calendar-print-iso-date).
p j
Display Julian date for selected day (calendar-print-julian-date).
p a
Display astronomical (Julian) day number for selected day (calendar-print-astro-day-number).
p h
Display Hebrew date for selected day (calendar-print-hebrew-date).
p i
Display Islamic date for selected day (calendar-print-islamic-date).
p f
Display French Revolutionary date for selected day (calendar-print-french-date).
p C
Display Chinese date for selected day (calendar-print-chinese-date).
p k
Display Coptic date for selected day (calendar-print-coptic-date).
p e
Display Ethiopic date for selected day (calendar-print-ethiopic-date).
p p
Display Persian date for selected day (calendar-print-persian-date).
p m
Display Mayan date for selected day (calendar-print-mayan-date).

If you are using X, the easiest way to translate a date into other calendars is to click on it with Button2, then choose Other Calendars from the menu that appears. This displays the equivalent forms of the date in all the calendars Emacs understands, in the form of a menu. (Choosing an alternative from this menu doesn't actually do anything--the menu is used only for display.)

Put point on the desired date of the Gregorian calendar, then type the appropriate keys. The p is a mnemonic for "print" since Emacs "prints" the equivalent date in the echo area.


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26.5 Converting From Other Calendars

You can use the other supported calendars to specify a date to move to. This section describes the commands for doing this using calendars other than Mayan; for the Mayan calendar, see the following section.

g c
Move to a date specified in the ISO commercial calendar (calendar-goto-iso-date).
g j
Move to a date specified in the Julian calendar (calendar-goto-julian-date).
g a
Move to a date specified in astronomical (Julian) day number (calendar-goto-astro-day-number).
g h
Move to a date specified in the Hebrew calendar (calendar-goto-hebrew-date).
g i
Move to a date specified in the Islamic calendar (calendar-goto-islamic-date).
g f
Move to a date specified in the French Revolutionary calendar (calendar-goto-french-date).
g C
Move to a date specified in the Chinese calendar (calendar-goto-chinese-date).
g p
Move to a date specified in the Persian calendar (calendar-goto-persian-date).
g k
Move to a date specified in the Coptic calendar (calendar-goto-coptic-date).
g e
Move to a date specified in the Ethiopic calendar (calendar-goto-ethiopic-date).

These commands ask you for a date on the other calendar, move point to the Gregorian calendar date equivalent to that date, and display the other calendar's date in the echo area. Emacs uses strict completion (see section 6.3 Completion) whenever it asks you to type a month name, so you don't have to worry about the spelling of Hebrew, Islamic, or French names.

One common question concerning the Hebrew calendar is the computation of the anniversary of a date of death, called a "yahrzeit." The Emacs calendar includes a facility for such calculations. If you are in the calendar, the command M-x list-yahrzeit-dates asks you for a range of years and then displays a list of the yahrzeit dates for those years for the date given by point. If you are not in the calendar, this command first asks you for the date of death and the range of years, and then displays the list of yahrzeit dates.


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26.5.1 Converting from the Mayan Calendar

Here are the commands to select dates based on the Mayan calendar:

g m l
Move to a date specified by the long count calendar (calendar-goto-mayan-long-count-date).
g m n t
Move to the next occurrence of a place in the tzolkin calendar (calendar-next-tzolkin-date).
g m p t
Move to the previous occurrence of a place in the tzolkin calendar (calendar-previous-tzolkin-date).
g m n h
Move to the next occurrence of a place in the haab calendar (calendar-next-haab-date).
g m p h
Move to the previous occurrence of a place in the haab calendar (calendar-previous-haab-date).
g m n c
Move to the next occurrence of a place in the calendar round (calendar-next-calendar-round-date).
g m p c
Move to the previous occurrence of a place in the calendar round (calendar-previous-calendar-round-date).

To understand these commands, you need to understand the Mayan calendars. The long count is a counting of days with these units:

 
1 kin = 1 day   1 uinal = 20 kin   1 tun = 18 uinal
1 katun = 20 tun   1 baktun = 20 katun

Thus, the long count date 12.16.11.16.6 means 12 baktun, 16 katun, 11 tun, 16 uinal, and 6 kin. The Emacs calendar can handle Mayan long count dates as early as 7.17.18.13.1, but no earlier. When you use the g m l command, type the Mayan long count date with the baktun, katun, tun, uinal, and kin separated by periods.

The Mayan tzolkin calendar is a cycle of 260 days formed by a pair of independent cycles of 13 and 20 days. Since this cycle repeats endlessly, Emacs provides commands to move backward and forward to the previous or next point in the cycle. Type g m p t to go to the previous tzolkin date; Emacs asks you for a tzolkin date and moves point to the previous occurrence of that date. Similarly, type g m n t to go to the next occurrence of a tzolkin date.

The Mayan haab calendar is a cycle of 365 days arranged as 18 months of 20 days each, followed a 5-day monthless period. Like the tzolkin cycle, this cycle repeats endlessly, and there are commands to move backward and forward to the previous or next point in the cycle. Type g m p h to go to the previous haab date; Emacs asks you for a haab date and moves point to the previous occurrence of that date. Similarly, type g m n h to go to the next occurrence of a haab date.

The Maya also used the combination of the tzolkin date and the haab date. This combination is a cycle of about 52 years called a calendar round. If you type g m p c, Emacs asks you for both a haab and a tzolkin date and then moves point to the previous occurrence of that combination. Use g m n c to move point to the next occurrence of a combination. These commands signal an error if the haab/tzolkin date combination you have typed is impossible.

Emacs uses strict completion (see section 6.3 Completion) whenever it asks you to type a Mayan name, so you don't have to worry about spelling.


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26.5.2 The Diary

The Emacs diary keeps track of appointments or other events on a daily basis, in conjunction with the calendar. To use the diary feature, you must first create a diary file containing a list of events and their dates. Then Emacs can automatically pick out and display the events for today, for the immediate future, or for any specified date.

By default, Emacs uses `~/diary' as the diary file. This is the same file that the calendar utility uses. A sample `~/diary' file is:

 
12/22/1988 Twentieth wedding anniversary!!
&1/1. Happy New Year!
10/22 Ruth's birthday.
* 21, *: Payday
Tuesday--weekly meeting with grad students at 10am
         Supowit, Shen, Bitner, and Kapoor to attend.
1/13/89 Friday the thirteenth!!
&thu 4pm squash game with Lloyd.
mar 16 Dad's birthday
April 15, 1989 Income tax due.
&* 15 time cards due.

This example uses extra spaces to align the event descriptions of most of the entries. Such formatting is purely a matter of taste.

Although you probably will start by creating a diary manually, Emacs provides a number of commands to let you view, add, and change diary entries. You can also share diary entries with other users (see section 26.5.8.9 Included Diary Files).

26.5.3 Commands Displaying Diary Entries  Viewing diary entries and associated calendar dates.
26.5.4 The Diary File  Entering events in your diary.
26.5.5 Date Formats  Various ways you can specify dates.
26.5.6 Commands to Add to the Diary  Commands to create diary entries.
26.5.7 Special Diary Entries  Anniversaries, blocks of dates, cyclic entries, etc.


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26.5.3 Commands Displaying Diary Entries

Once you have created a `~/diary' file, you can use the calendar to view it. You can also view today's events outside of Calendar mode.

d
Display all diary entries for the selected date (view-diary-entries).
Button2 Diary
Display all diary entries for the date you click on.
s
Display the entire diary file (show-all-diary-entries).
m
Mark all visible dates that have diary entries (mark-diary-entries).
u
Unmark the calendar window (calendar-unmark).
M-x print-diary-entries
Print hard copy of the diary display as it appears.
M-x diary
Display all diary entries for today's date.
M-x diary-mail-entries
Mail yourself email reminders about upcoming diary entries.

Displaying the diary entries with d shows in a separate window the diary entries for the selected date in the calendar. The mode line of the new window shows the date of the diary entries and any holidays that fall on that date. If you specify a numeric argument with d, it shows all the diary entries for that many successive days. Thus, 2 d displays all the entries for the selected date and for the following day.

Another way to display the diary entries for a date is to click Button2 on the date, and then choose Diary from the menu that appears.

To get a broader view of which days are mentioned in the diary, use the m command. This displays the dates that have diary entries in a different face (or places a `+' after these dates, if display with multiple faces is not available). The command applies both to the currently visible months and to other months that subsequently become visible by scrolling. To turn marking off and erase the current marks, type u, which also turns off holiday marks (see section 26.2.1 Holidays).

To see the full diary file, rather than just some of the entries, use the s command.

Display of selected diary entries uses the selective display feature to hide entries that don't apply.

The diary buffer as you see it is an illusion, so simply printing the buffer does not print what you see on your screen. There is a special command to print hard copy of the diary buffer as it appears; this command is M-x print-diary-entries. It sends the data directly to the printer. You can customize it like lpr-region (see section 26.9 Hardcopy Output).

The command M-x diary displays the diary entries for the current date, independently of the calendar display, and optionally for the next few days as well; the variable number-of-diary-entries specifies how many days to include (see section 27. Customization).

If you put (diary) in your init file, this automatically displays a window with the day's diary entries, when you enter Emacs. See section 27.7 The Init File. The mode line of the displayed window shows the date and any holidays that fall on that date.

Many users like to receive notice of events in their diary as email. To send such mail to yourself, use the command M-x diary-mail-entries. A prefix argument specifies how many days (starting with today) to check; otherwise, the variable diary-mail-days says how many days.


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26.5.4 The Diary File

Your diary file is a file that records events associated with particular dates. The name of the diary file is specified by the variable diary-file; `~/diary' is the default. The calendar utility program supports a subset of the format allowed by the Emacs diary facilities, so you can use that utility to view the diary file, with reasonable results aside from the entries it cannot understand.

Each entry in the diary file describes one event and consists of one or more lines. An entry always begins with a date specification at the left margin. The rest of the entry is simply text to describe the event. If the entry has more than one line, then the lines after the first must begin with whitespace to indicate they continue a previous entry. Lines that do not begin with valid dates and do not continue a preceding entry are ignored.

You can inhibit the marking of certain diary entries in the calendar window; to do this, insert an ampersand (`&') at the beginning of the entry, before the date. This has no effect on display of the entry in the diary window; it affects only marks on dates in the calendar window. Nonmarking entries are especially useful for generic entries that would otherwise mark many different dates.

If the first line of a diary entry consists only of the date or day name with no following blanks or punctuation, then the diary window display doesn't include that line; only the continuation lines appear. For example, this entry:

 
02/11/1989
      Bill B. visits Princeton today
      2pm Cognitive Studies Committee meeting
      2:30-5:30 Liz at Lawrenceville
      4:00pm Dentist appt
      7:30pm Dinner at George's
      8:00-10:00pm concert

appears in the diary window without the date line at the beginning. This style of entry looks neater when you display just a single day's entries, but can cause confusion if you ask for more than one day's entries.

You can edit the diary entries as they appear in the window, but it is important to remember that the buffer displayed contains the entire diary file, with portions of it concealed from view. This means, for instance, that the C-f (forward-char) command can put point at what appears to be the end of the line, but what is in reality the middle of some concealed line.

Be careful when editing the diary entries! Inserting additional lines or adding/deleting characters in the middle of a visible line cannot cause problems, but editing at the end of a line may not do what you expect. Deleting a line may delete other invisible entries that follow it. Before editing the diary, it is best to display the entire file with s (show-all-diary-entries).


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26.5.5 Date Formats

Here are some sample diary entries, illustrating different ways of formatting a date. The examples all show dates in American order (month, day, year), but Calendar mode supports European order (day, month, year) as an option.

 
4/20/93  Switch-over to new tabulation system
apr. 25  Start tabulating annual results
4/30  Results for April are due
*/25  Monthly cycle finishes
Friday  Don't leave without backing up files

The first entry appears only once, on April 20, 1993. The second and third appear every year on the specified dates, and the fourth uses a wildcard (asterisk) for the month, so it appears on the 25th of every month. The final entry appears every week on Friday.

You can use just numbers to express a date, as in `month/day' or `month/day/year'. This must be followed by a nondigit. In the date itself, month and day are numbers of one or two digits. The optional year is also a number, and may be abbreviated to the last two digits; that is, you can use `11/12/1989' or `11/12/89'.

Dates can also have the form `monthname day' or `monthname day, year', where the month's name can be spelled in full or abbreviated to three characters (with or without a period). Case is not significant.

A date may be generic; that is, partially unspecified. Then the entry applies to all dates that match the specification. If the date does not contain a year, it is generic and applies to any year. Alternatively, month, day, or year can be a `*'; this matches any month, day, or year, respectively. Thus, a diary entry `3/*/*' matches any day in March of any year; so does `march *'.

If you prefer the European style of writing dates--in which the day comes before the month--type M-x european-calendar while in the calendar, or set the variable european-calendar-style to t before using any calendar or diary command. This mode interprets all dates in the diary in the European manner, and also uses European style for displaying diary dates. (Note that there is no comma after the monthname in the European style.) To go back to the (default) American style of writing dates, type M-x american-calendar. You can use the name of a day of the week as a generic date which applies to any date falling on that day of the week. You can abbreviate the day of the week to three letters (with or without a period) or spell it in full; case is not significant.


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26.5.6 Commands to Add to the Diary

While in the calendar, there are several commands to create diary entries:

i d
Add a diary entry for the selected date (insert-diary-entry).
i w
Add a diary entry for the selected day of the week (insert-weekly-diary-entry).
i m
Add a diary entry for the selected day of the month (insert-monthly-diary-entry).
i y
Add a diary entry for the selected day of the year (insert-yearly-diary-entry).

You can make a diary entry for a specific date by selecting that date in the calendar window and typing the i d command. This command displays the end of your diary file in another window and inserts the date; you can then type the rest of the diary entry.

If you want to make a diary entry that applies to a specific day of the week, select that day of the week (any occurrence will do) and type i w. This inserts the day-of-week as a generic date; you can then type the rest of the diary entry. You can make a monthly diary entry in the same fashion. Select the day of the month, use the i m command, and type rest of the entry. Similarly, you can insert a yearly diary entry with the i y command.

All of the above commands make marking diary entries by default. To make a nonmarking diary entry, give a numeric argument to the command. For example, C-u i w makes a nonmarking weekly diary entry.

When you modify the diary file, be sure to save the file before exiting Emacs.


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26.5.7 Special Diary Entries

In addition to entries based on calendar dates, the diary file can contain sexp entries for regular events such as anniversaries. These entries are based on Lisp expressions (sexps) that Emacs evaluates as it scans the diary file. Instead of a date, a sexp entry contains `%%' followed by a Lisp expression which must begin and end with parentheses. The Lisp expression determines which dates the entry applies to.

Calendar mode provides commands to insert certain commonly used sexp entries:

i a
Add an anniversary diary entry for the selected date (insert-anniversary-diary-entry).
i b
Add a block diary entry for the current region (insert-block-diary-entry).
i c
Add a cyclic diary entry starting at the date (insert-cyclic-diary-entry).

If you want to make a diary entry that applies to the anniversary of a specific date, move point to that date and use the i a command. This displays the end of your diary file in another window and inserts the anniversary description; you can then type the rest of the diary entry. The entry looks like this:

The effect of i a is to add a diary-anniversary sexp to your diary file. You can also add one manually, for instance:

 
%%(diary-anniversary 10 31 1948) Arthur's birthday

This entry applies to October 31 in any year after 1948; `10 31 1948' specifies the date. (If you are using the European calendar style, the month and day are interchanged.) The reason this expression requires a beginning year is that advanced diary functions can use it to calculate the number of elapsed years.

A block diary entry applies to a specified range of consecutive dates. Here is a block diary entry that applies to all dates from June 24, 1990 through July 10, 1990:

 
%%(diary-block 6 24 1990 7 10 1990) Vacation

The `6 24 1990' indicates the starting date and the `7 10 1990' indicates the stopping date. (Again, if you are using the European calendar style, the month and day are interchanged.)

To insert a block entry, place point and the mark on the two dates that begin and end the range, and type i b. This command displays the end of your diary file in another window and inserts the block description; you can then type the diary entry.

Cyclic diary entries repeat after a fixed interval of days. To create one, select the starting date and use the i c command. The command prompts for the length of interval, then inserts the entry, which looks like this:

 
%%(diary-cyclic 50 3 1 1990) Renew medication

This entry applies to March 1, 1990 and every 50th day following; `3 1 1990' specifies the starting date. (If you are using the European calendar style, the month and day are interchanged.)

All three of these commands make marking diary entries. To insert a nonmarking entry, give a numeric argument to the command. For example, C-u i a makes a nonmarking anniversary diary entry.

Marking sexp diary entries in the calendar is extremely time-consuming, since every date visible in the calendar window must be individually checked. So it's a good idea to make sexp diary entries nonmarking (with `&') when possible.

Another sophisticated kind of sexp entry, a floating diary entry, specifies a regularly occurring event by offsets specified in days, weeks, and months. It is comparable to a crontab entry interpreted by the cron utility. Here is a nonmarking, floating diary entry that applies to the last Thursday in November:

 
&%%(diary-float 11 4 -1) American Thanksgiving

The 11 specifies November (the eleventh month), the 4 specifies Thursday (the fourth day of the week, where Sunday is numbered zero), and the -1 specifies "last" (1 would mean "first", 2 would mean "second", -2 would mean "second-to-last", and so on). The month can be a single month or a list of months. Thus you could change the 11 above to `'(1 2 3)' and have the entry apply to the last Thursday of January, February, and March. If the month is t, the entry applies to all months of the year.

The sexp feature of the diary allows you to specify diary entries based on any Emacs Lisp expression. You can use the library of built-in functions or you can write your own functions. The built-in functions include the ones shown in this section, plus a few others (see section 26.5.8.10 Sexp Entries and the Fancy Diary Display).

The generality of sexps lets you specify any diary entry that you can describe algorithmically. Suppose you get paid on the 21st of the month if it is a weekday, and to the Friday before if the 21st is on a weekend. The diary entry

 
&%%(let ((dayname (calendar-day-of-week date))
         (day (car (cdr date))))
      (or (and (= day 21) (memq dayname '(1 2 3 4 5)))
          (and (memq day '(19 20)) (= dayname 5)))
         ) Pay check deposited

to just those dates. This example illustrates how the sexp can depend on the variable date; this variable is a list (month day year) that gives the Gregorian date for which the diary entries are being found. If the value of the sexp is t, the entry applies to that date. If the sexp evaluates to nil, the entry does not apply to that date.


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26.5.8 Customizing the Calendar and Diary

There are many customizations that you can use to make the calendar and diary suit your personal tastes.

26.5.8.1 Customizing the Calendar  Defaults you can set.
26.5.8.2 Customizing the Holidays  Defining your own holidays.
26.5.8.3 Date Display Format  Changing the format.
26.5.8.4 Time Display Format  Changing the format.
26.5.8.5 Daylight Savings Time  Changing the default.
26.5.8.6 Customizing the Diary  Defaults you can set.
26.5.8.7 Hebrew- and Islamic-Date Diary Entries  How to obtain them.
26.5.8.8 Fancy Diary Display  Enhancing the diary display, sorting entries.
26.5.8.9 Included Diary Files  Sharing a common diary file.
26.5.8.10 Sexp Entries and the Fancy Diary Display  Fancy things you can do.
26.5.8.11 Customizing Appointment Reminders  Customizing appointment reminders.


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26.5.8.1 Customizing the Calendar

If you set the variable view-diary-entries-initially to t, calling up the calendar automatically displays the diary entries for the current date as well. The diary dates appear only if the current date is visible. If you add both of the following lines to your init file:

 
(setq view-diary-entries-initially t)
(calendar)

this displays both the calendar and diary windows whenever you start Emacs. See section 27.7 The Init File.

Similarly, if you set the variable view-calendar-holidays-initially to t, entering the calendar automatically displays a list of holidays for the current three-month period. The holiday list appears in a separate window. You can set the variable mark-diary-entries-in-calendar to t in order to mark any dates with diary entries. This takes effect whenever the calendar window contents are recomputed. There are two ways of marking these dates: by changing the face (see section 27.9 Faces), if the display supports that, or by placing a plus sign (`+') beside the date otherwise.

Similarly, setting the variable mark-holidays-in-calendar to t marks holiday dates, either with a change of face or with an asterisk (`*').

The variable calendar-holiday-marker specifies how to mark a date as being a holiday. Its value may be a character to insert next to the date, or a face name to use for displaying the date. Likewise, the variable diary-entry-marker specifies how to mark a date that has diary entries. The calendar creates faces named holiday-face and diary-face for these purposes; those symbols are the default values of these variables, when Emacs supports multiple faces on your terminal.

The variable calendar-load-hook is a normal hook run when the calendar package is first loaded (before actually starting to display the calendar).

Starting the calendar runs the normal hook initial-calendar-window-hook. Recomputation of the calendar display does not run this hook. But if you leave the calendar with the q command and reenter it, the hook runs again.

The variable today-visible-calendar-hook is a normal hook run after the calendar buffer has been prepared with the calendar when the current date is visible in the window. One use of this hook is to replace today's date with asterisks; to do that, use the hook function calendar-star-date.

 
(add-hook 'today-visible-calendar-hook 'calendar-star-date)

Another standard hook function marks the current date, either by changing its face or by adding an asterisk. Here's how to use it:

 
(add-hook 'today-visible-calendar-hook 'calendar-mark-today)

The variable calendar-today-marker specifies how to mark today's date. Its value should be a character to insert next to the date or a face name to use for displaying the date. A face named calendar-today-face is provided for this purpose; that symbol is the default for this variable when Emacs supports multiple faces on your terminal.

A similar normal hook, today-invisible-calendar-hook is run if the current date is not visible in the window.


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26.5.8.2 Customizing the Holidays

Emacs knows about holidays defined by entries on one of several lists. You can customize these lists of holidays to your own needs, adding or deleting holidays. The lists of holidays that Emacs uses are for general holidays (general-holidays), local holidays (local-holidays), Christian holidays (christian-holidays), Hebrew (Jewish) holidays (hebrew-holidays), Islamic (Moslem) holidays (islamic-holidays), and other holidays (other-holidays).

The general holidays are, by default, holidays common throughout the United States. To eliminate these holidays, set general-holidays to nil.

There are no default local holidays (but sites may supply some). You can set the variable local-holidays to any list of holidays, as described below.

By default, Emacs does not include all the holidays of the religions that it knows, only those commonly found in secular calendars. For a more extensive collection of religious holidays, you can set any (or all) of the variables all-christian-calendar-holidays, all-hebrew-calendar-holidays, or all-islamic-calendar-holidays to t. If you want to eliminate the religious holidays, set any or all of the corresponding variables christian-holidays, hebrew-holidays, and islamic-holidays to nil.

You can set the variable other-holidays to any list of holidays. This list, normally empty, is intended for individual use.

Each of the lists (general-holidays, local-holidays, christian-holidays, hebrew-holidays, islamic-holidays, and other-holidays) is a list of holiday forms, each holiday form describing a holiday (or sometimes a list of holidays).

Here is a table of the possible kinds of holiday form. Day numbers and month numbers count starting from 1, but "dayname" numbers count Sunday as 0. The element string is always the name of the holiday, as a string.

(holiday-fixed month day string)
A fixed date on the Gregorian calendar. month and day are numbers, string is the name of the holiday.

(holiday-float month dayname k string)
The kth dayname in month on the Gregorian calendar (dayname=0 for Sunday, and so on); negative k means count back from the end of the month. string is the name of the holiday.

(holiday-hebrew month day string)
A fixed date on the Hebrew calendar. month and day are numbers, string is the name of the holiday.

(holiday-islamic month day string)
A fixed date on the Islamic calendar. month and day are numbers, string is the name of the holiday.

(holiday-julian month day string)
A fixed date on the Julian calendar. month and day are numbers, string is the name of the holiday.

(holiday-sexp sexp string)
A date calculated by the Lisp expression sexp. The expression should use the variable year to compute and return the date of a holiday, or nil if the holiday doesn't happen this year. The value of sexp must represent the date as a list of the form (month day year). string is the name of the holiday.

(if condition holiday-form &optional holiday-form)
A holiday that happens only if condition is true.

(function [args])
A list of dates calculated by the function function, called with arguments args.

For example, suppose you want to add Bastille Day, celebrated in France on July 14. You can do this by adding the following line to your init file:

 
(setq other-holidays '((holiday-fixed 7 14 "Bastille Day")))

See section 27.7 The Init File.

The holiday form (holiday-fixed 7 14 "Bastille Day") specifies the fourteenth day of the seventh month (July).

Many holidays occur on a specific day of the week, at a specific time of month. Here is a holiday form describing Hurricane Supplication Day, celebrated in the Virgin Islands on the fourth Monday in August:

 
(holiday-float 8 1 4 "Hurricane Supplication Day")

Here the 8 specifies August, the 1 specifies Monday (Sunday is 0, Tuesday is 2, and so on), and the 4 specifies the fourth occurrence in the month (1 specifies the first occurrence, 2 the second occurrence, -1 the last occurrence, -2 the second-to-last occurrence, and so on).

You can specify holidays that occur on fixed days of the Hebrew, Islamic, and Julian calendars too. For example,

 
(setq other-holidays
      '((holiday-hebrew 10 2 "Last day of Hanukkah")
        (holiday-islamic 3 12 "Mohammed's Birthday")
        (holiday-julian 4 2 "Jefferson's Birthday")))

adds the last day of Hanukkah (since the Hebrew months are numbered with 1 starting from Nisan), the Islamic feast celebrating Mohammed's birthday (since the Islamic months are numbered from 1 starting with Muharram), and Thomas Jefferson's birthday, which is 2 April 1743 on the Julian calendar.

To include a holiday conditionally, use either Emacs Lisp's if or the holiday-sexp form. For example, American presidential elections occur on the first Tuesday after the first Monday in November of years divisible by 4:

 
(holiday-sexp (if (= 0 (% year 4))
                   (calendar-gregorian-from-absolute
                 (1+ (calendar-dayname-on-or-before
                       1 (+ 6 (calendar-absolute-from-gregorian
                                (list 11 1 year))))))
              "US Presidential Election"))

or

 
(if (= 0 (% displayed-year 4))
    (fixed 11
           (extract-calendar-day
             (calendar-gregorian-from-absolute
               (1+ (calendar-dayname-on-or-before
                     1 (+ 6 (calendar-absolute-from-gregorian
                              (list 11 1 displayed-year)))))))
           "US Presidential Election"))

Some holidays just don't fit into any of these forms because special calculations are involved in their determination. In such cases you must write a Lisp function to do the calculation. To include eclipses, for example, add (eclipses) to other-holidays and write an Emacs Lisp function eclipses that returns a (possibly empty) list of the relevant Gregorian dates among the range visible in the calendar window, with descriptive strings, like this:

 
(((6 27 1991) "Lunar Eclipse") ((7 11 1991) "Solar Eclipse") ... )


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26.5.8.3 Date Display Format

You can customize the manner of displaying dates in the diary, in mode lines, and in messages by setting calendar-date-display-form. This variable holds a list of expressions that can involve the variables month, day, and year, which are all numbers in string form, and monthname and dayname, which are both alphabetic strings. In the American style, the default value of this list is as follows:

 
((if dayname (concat dayname ", ")) monthname " " day ", " year)

while in the European style this value is the default:

 
((if dayname (concat dayname ", ")) day " " monthname " " year)

+The ISO standard date representation is this:

 
(year "-" month "-" day)

This specifies a typical American format:

 
(month "/" day "/" (substring year -2))


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26.5.8.4 Time Display Format

The calendar and diary by default display times of day in the conventional American style with the hours from 1 through 12, minutes, and either `am' or `pm'. If you prefer the European style, also known in the US as military, in which the hours go from 00 to 23, you can alter the variable calendar-time-display-form. This variable is a list of expressions that can involve the variables 12-hours, 24-hours, and minutes, which are all numbers in string form, and am-pm and time-zone, which are both alphabetic strings. The default value of calendar-time-display-form is as follows:

 
(12-hours ":" minutes am-pm
          (if time-zone " (") time-zone (if time-zone ")"))

Here is a value that provides European style times:

 
(24-hours ":" minutes
          (if time-zone " (") time-zone (if time-zone ")"))

gives military-style times like `21:07 (UT)' if time zone names are defined, and times like `21:07' if they are not.


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26.5.8.5 Daylight Savings Time

Emacs understands the difference between standard time and daylight savings time--the times given for sunrise, sunset, solstices, equinoxes, and the phases of the moon take that into account. The rules for daylight savings time vary from place to place and have also varied historically from year to year. To do the job properly, Emacs needs to know which rules to use.

Some operating systems keep track of the rules that apply to the place where you are; on these systems, Emacs gets the information it needs from the system automatically. If some or all of this information is missing, Emacs fills in the gaps with the rules currently used in Cambridge, Massachusetts. If the resulting rules are not what you want, you can tell Emacs the rules to use by setting certain variables.

If the default choice of rules is not appropriate for your location, you can tell Emacs the rules to use by setting the variables calendar-daylight-savings-starts and calendar-daylight-savings-ends. Their values should be Lisp expressions that refer to the variable year, and evaluate to the Gregorian date on which daylight savings time starts or (respectively) ends, in the form of a list (month day year). The values should be nil if your area does not use daylight savings time.

Emacs uses these expressions to determine the starting date of daylight savings time for the holiday list and for correcting times of day in the solar and lunar calculations. The values for Cambridge, Massachusetts are as follows:

 
(calendar-nth-named-day 1 0 4 year)
(calendar-nth-named-day -1 0 10 year)

That is, the first 0th day (Sunday) of the fourth month (April) in the year specified by year, and the last Sunday of the tenth month (October) of that year. If daylight savings time were changed to start on October 1, you would set calendar-daylight-savings-starts to this:

 
(list 10 1 year)

For a more complex example, suppose daylight savings time begins on the first of Nisan on the Hebrew calendar. You should set calendar-daylight-savings-starts to this value:

 
(calendar-gregorian-from-absolute
  (calendar-absolute-from-hebrew
    (list 1 1 (+ year 3760))))

because Nisan is the first month in the Hebrew calendar and the Hebrew year differs from the Gregorian year by 3760 at Nisan.

If there is no daylight savings time at your location, or if you want all times in standard time, set calendar-daylight-savings-starts and calendar-daylight-savings-ends to nil.

The variable calendar-daylight-time-offset specifies the difference between daylight savings time and standard time, measured in minutes. The value for Cambridge, Massachusetts is 60.

The two variables calendar-daylight-savings-starts-time and calendar-daylight-savings-ends-time specify the number of minutes after midnight local time when the transition to and from daylight savings time should occur. For Cambridge, Massachusetts both variables' values are 120.


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26.5.8.6 Customizing the Diary

Ordinarily, the mode line of the diary buffer window indicates any holidays that fall on the date of the diary entries. The process of checking for holidays can take several seconds, so including holiday information delays the display of the diary buffer noticeably. If you'd prefer to have a faster display of the diary buffer but without the holiday information, set the variable holidays-in-diary-buffer to nil.

The variable number-of-diary-entries controls the number of days of diary entries to be displayed at one time. It affects the initial display when view-diary-entries-initially is t, as well as the command M-x diary. For example, the default value is 1, which says to display only the current day's diary entries. If the value is 2, both the current day's and the next day's entries are displayed. The value can also be a vector of seven elements: for example, if the value is [0 2 2 2 2 4 1] then no diary entries appear on Sunday, the current date's and the next day's diary entries appear Monday through Thursday, Friday through Monday's entries appear on Friday, while on Saturday only that day's entries appear.

The variable print-diary-entries-hook is a normal hook run after preparation of a temporary buffer containing just the diary entries currently visible in the diary buffer. (The other, irrelevant diary entries are really absent from the temporary buffer; in the diary buffer, they are merely hidden.) The default value of this hook does the printing with the command lpr-buffer. If you want to use a different command to do the printing, just change the value of this hook. Other uses might include, for example, rearranging the lines into order by day and time.

You can customize the form of dates in your diary file, if neither the standard American nor European styles suits your needs, by setting the variable diary-date-forms. This variable is a list of patterns for recognizing a date. Each date pattern is a list whose elements may be regular expressions (see section 12.5 Syntax of Regular Expressions) or the symbols month, day, year, monthname, and dayname. All these elements serve as patterns that match certain kinds of text in the diary file. In order for the date pattern, as a whole, to match, all of its elements must match consecutively.

A regular expression in a date pattern matches in its usual fashion, using the standard syntax table altered so that `*' is a word constituent.

The symbols month, day, year, monthname, and dayname match the month number, day number, year number, month name, and day name of the date being considered. The symbols that match numbers allow leading zeros; those that match names allow three-letter abbreviations and capitalization. All the symbols can match `*'; since `*' in a diary entry means "any day", "any month", and so on, it should match regardless of the date being considered.

The default value of diary-date-forms in the American style is this:

 
((month "/" day "[^/0-9]")
 (month "/" day "/" year "[^0-9]")
 (monthname " *" day "[^,0-9]")
 (monthname " *" day ", *" year "[^0-9]")
 (dayname "\\W"))

Emacs matches of the diary entries with the date forms is done with the standard syntax table from Fundamental mode (see section `Syntax Tables' in XEmacs Lisp Reference Manual), but with the `*' changed so that it is a word constituent.

The date patterns in the list must be mutually exclusive and must not match any portion of the diary entry itself, just the date and one character of whitespace. If, to be mutually exclusive, the pattern must match a portion of the diary entry text--beyond the whitespace that ends the date--then the first element of the date pattern must be backup. This causes the date recognizer to back up to the beginning of the current word of the diary entry, after finishing the match. Even if you use backup, the date pattern must absolutely not match more than a portion of the first word of the diary entry. The default value of diary-date-forms in the European style is this list:

 
((day "/" month "[^/0-9]")
 (day "/" month "/" year "[^0-9]")
 (backup day " *" monthname "\\W+\\<[^*0-9]")
 (day " *" monthname " *" year "[^0-9]")
 (dayname "\\W"))

Notice the use of backup in the third pattern, because it needs to match part of a word beyond the date itself to distinguish it from the fourth pattern.


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26.5.8.7 Hebrew- and Islamic-Date Diary Entries

Your diary file can have entries based on Hebrew or Islamic dates, as well as entries based on the world-standard Gregorian calendar. However, because recognition of such entries is time-consuming and most people don't use them, you must explicitly enable their use. If you want the diary to recognize Hebrew-date diary entries, for example, you must do this:

 
(add-hook 'nongregorian-diary-listing-hook 'list-hebrew-diary-entries)
(add-hook 'nongregorian-diary-marking-hook 'mark-hebrew-diary-entries)

If you want Islamic-date entries, do this:

 
(add-hook 'nongregorian-diary-listing-hook 'list-islamic-diary-entries)
(add-hook 'nongregorian-diary-marking-hook 'mark-islamic-diary-entries)

Hebrew- and Islamic-date diary entries have the same formats as Gregorian-date diary entries, except that `H' precedes a Hebrew date and `I' precedes an Islamic date. Moreover, because the Hebrew and Islamic month names are not uniquely specified by the first three letters, you may not abbreviate them. For example, a diary entry for the Hebrew date Heshvan 25 could look like this:

 
HHeshvan 25 Happy Hebrew birthday!

and would appear in the diary for any date that corresponds to Heshvan 25 on the Hebrew calendar. And here is Islamic-date diary entry that matches Dhu al-Qada 25:

 
IDhu al-Qada 25 Happy Islamic birthday!

and would appear in the diary for any date that corresponds to Dhu al-Qada 25 on the Islamic calendar.

As with Gregorian-date diary entries, Hebrew- and Islamic-date entries are nonmarking if they are preceded with an ampersand (`&').

Here is a table of commands used in the calendar to create diary entries that match the selected date and other dates that are similar in the Hebrew or Islamic calendar:

i h d
Add a diary entry for the Hebrew date corresponding to the selected date (insert-hebrew-diary-entry).
i h m
Add a diary entry for the day of the Hebrew month corresponding to the selected date (insert-monthly-hebrew-diary-entry). This diary entry matches any date that has the same Hebrew day-within-month as the selected date.
i h y
Add a diary entry for the day of the Hebrew year corresponding to the selected date (insert-yearly-hebrew-diary-entry). This diary entry matches any date which has the same Hebrew month and day-within-month as the selected date.
i i d
Add a diary entry for the Islamic date corresponding to the selected date (insert-islamic-diary-entry).
i i m
Add a diary entry for the day of the Islamic month corresponding to the selected date (insert-monthly-islamic-diary-entry).
i i y
Add a diary entry for the day of the Islamic year corresponding to the selected date (insert-yearly-islamic-diary-entry).

These commands work much like the corresponding commands for ordinary diary entries: they apply to the date that point is on in the calendar window, and what they do is insert just the date portion of a diary entry at the end of your diary file. You must then insert the rest of the diary entry.


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26.5.8.8 Fancy Diary Display

Diary display works by preparing the diary buffer and then running the hook diary-display-hook. The default value of this hook (simple-diary-display) hides the irrelevant diary entries and then displays the buffer. However, if you specify the hook as follows,

 
(add-hook 'diary-display-hook 'fancy-diary-display)

this enables fancy diary display. It displays diary entries and holidays by copying them into a special buffer that exists only for the sake of display. Copying to a separate buffer provides an opportunity to change the displayed text to make it prettier--for example, to sort the entries by the dates they apply to.

As with simple diary display, you can print a hard copy of the buffer with print-diary-entries. To print a hard copy of a day-by-day diary for a week by positioning point on Sunday of that week, type 7 d and then do M-x print-diary-entries. As usual, the inclusion of the holidays slows down the display slightly; you can speed things up by setting the variable holidays-in-diary-buffer to nil.

Ordinarily, the fancy diary buffer does not show days for which there are no diary entries, even if that day is a holiday. If you want such days to be shown in the fancy diary buffer, set the variable diary-list-include-blanks to t.

If you use the fancy diary display, you can use the normal hook list-diary-entries-hook to sort each day's diary entries by their time of day. Add this line to your init file:

 
(add-hook 'list-diary-entries-hook 'sort-diary-entries t)

See section 27.7 The Init File.

For each day, this sorts diary entries that begin with a recognizable time of day according to their times. Diary entries without times come first within each day.


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26.5.8.9 Included Diary Files

Fancy diary display also has the ability to process included diary files. This permits a group of people to share a diary file for events that apply to all of them. Lines in the diary file of this form:

 
#include "filename"

includes the diary entries from the file filename in the fancy diary buffer. The include mechanism is recursive, so that included files can include other files, and so on; you must be careful not to have a cycle of inclusions, of course. Here is how to enable the include facility:

 
(add-hook 'list-diary-entries-hook 'include-other-diary-files)
(add-hook 'mark-diary-entries-hook 'mark-included-diary-files)

The include mechanism works only with the fancy diary display, because ordinary diary display shows the entries directly from your diary file.


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26.5.8.10 Sexp Entries and the Fancy Diary Display

Sexp diary entries allow you to do more than just have complicated conditions under which a diary entry applies. If you use the fancy diary display, sexp entries can generate the text of the entry depending on the date itself. For example, an anniversary diary entry can insert the number of years since the anniversary date into the text of the diary entry. Thus the `%d' in this dairy entry:

 
%%(diary-anniversary 10 31 1948) Arthur's birthday (%d years old)

gets replaced by the age, so on October 31, 1990 the entry appears in the fancy diary buffer like this:

 
Arthur's birthday (42 years old)

If the diary file instead contains this entry:

 
%%(diary-anniversary 10 31 1948) Arthur's %d%s birthday

the entry in the fancy diary buffer for October 31, 1990 appears like this:

 
Arthur's 42nd birthday

Similarly, cyclic diary entries can interpolate the number of repetitions that have occurred:

 
%%(diary-cyclic 50 1 1 1990) Renew medication (%d%s time)

looks like this:

 
Renew medication (5th time)

in the fancy diary display on September 8, 1990.

The generality of sexp diary entries lets you specify any diary entry that you can describe algorithmically. A sexp diary entry contains an expression that computes whether the entry applies to any given date. If its value is non-nil, the entry applies to that date; otherwise, it does not. The expression can use the variable date to find the date being considered; its value is a list (month day year) that refers to the Gregorian calendar.

Suppose you get paid on the 21st of the month if it is a weekday, and on the Friday before if the 21st is on a weekend. Here is how to write a sexp diary entry that matches those dates:

 
&%%(let ((dayname (calendar-day-of-week date))
         (day (car (cdr date))))
      (or (and (= day 21) (memq dayname '(1 2 3 4 5)))
          (and (memq day '(19 20)) (= dayname 5)))
         ) Pay check deposited

applies to just those dates. This example illustrates how the sexp can depend on the variable date; this variable is a list (month day year) that gives the Gregorian date for which the diary entries are being found. If the value of the expression is t, the entry applies to that date. If the expression evaluates to nil, the entry does not apply to that date.

The following sexp diary entries take advantage of the ability (in the fancy diary display) to concoct diary entries whose text varies based on the date:

%%(diary-sunrise-sunset)
Make a diary entry for the local times of today's sunrise and sunset.
%%(diary-phases-of-moon)
Make a diary entry for the phases (quarters) of the moon.
%%(diary-day-of-year)
Make a diary entry with today's day number in the current year and the number of days remaining in the current year.
%%(diary-iso-date)
Make a diary entry with today's equivalent ISO commercial date.
%%(diary-julian-date)
Make a diary entry with today's equivalent date on the Julian calendar.
%%(diary-astro-day-number)
Make a diary entry with today's equivalent astronomical (Julian) day number.
%%(diary-hebrew-date)
Make a diary entry with today's equivalent date on the Hebrew calendar.
%%(diary-islamic-date)
Make a diary entry with today's equivalent date on the Islamic calendar.
%%(diary-french-date)
Make a diary entry with today's equivalent date on the French Revolutionary calendar.
%%(diary-mayan-date)
Make a diary entry with today's equivalent date on the Mayan calendar.

Thus including the diary entry

 
&%%(diary-hebrew-date)

causes every day's diary display to contain the equivalent date on the Hebrew calendar, if you are using the fancy diary display. (With simple diary display, the line `&%%(diary-hebrew-date)' appears in the diary for any date, but does nothing particularly useful.)

These functions can be used to construct sexp diary entries based on the Hebrew calendar in certain standard ways:

%%(diary-rosh-hodesh)
Make a diary entry that tells the occurrence and ritual announcement of each new Hebrew month.
%%(diary-parasha)
Make a Saturday diary entry that tells the weekly synagogue scripture reading.
%%(diary-sabbath-candles)
Make a Friday diary entry that tells the local time of Sabbath candle lighting.
%%(diary-omer)
Make a diary entry that gives the omer count, when appropriate.
%%(diary-yahrzeit month day year) name
Make a diary entry marking the anniversary of a date of death. The date is the Gregorian (civil) date of death. The diary entry appears on the proper Hebrew calendar anniversary and on the day before. (In the European style, the order of the parameters is changed to day, month, year.)


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26.5.8.11 Customizing Appointment Reminders

You can specify exactly how Emacs reminds you of an appointment, and how far in advance it begins doing so, by setting these variables:

appt-message-warning-time
The time in minutes before an appointment that the reminder begins. The default is 10 minutes.
appt-audible
If this is t (the default), Emacs rings the terminal bell for appointment reminders.
appt-visible
If this is t (the default), Emacs displays the appointment message in echo area.
appt-display-mode-line
If this is t (the default), Emacs displays the number of minutes to the appointment on the mode line.
appt-msg-window
If this is t (the default), Emacs displays the appointment message in another window.
appt-display-duration
The number of seconds an appointment message is displayed. The default is 5 seconds.


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26.6 Sorting Text

XEmacs provides several commands for sorting text in a buffer. All operate on the contents of the region (the text between point and the mark). They divide the text of the region into many sort records, identify a sort key for each record, and then reorder the records using the order determined by the sort keys. The records are ordered so that their keys are in alphabetical order, or, for numerical sorting, in numerical order. In alphabetical sorting, all upper-case letters `A' through `Z' come before lower-case `a', in accordance with the ASCII character sequence.

The sort commands differ in how they divide the text into sort records and in which part of each record they use as the sort key. Most of the commands make each line a separate sort record, but some commands use paragraphs or pages as sort records. Most of the sort commands use each entire sort record as its own sort key, but some use only a portion of the record as the sort key.

M-x sort-lines
Divide the region into lines and sort by comparing the entire text of a line. A prefix argument means sort in descending order.

M-x sort-paragraphs
Divide the region into paragraphs and sort by comparing the entire text of a paragraph (except for leading blank lines). A prefix argument means sort in descending order.

M-x sort-pages
Divide the region into pages and sort by comparing the entire text of a page (except for leading blank lines). A prefix argument means sort in descending order.

M-x sort-fields
Divide the region into lines and sort by comparing the contents of one field in each line. Fields are defined as separated by whitespace, so the first run of consecutive non-whitespace characters in a line constitutes field 1, the second such run constitutes field 2, etc.

You specify which field to sort by with a numeric argument: 1 to sort by field 1, etc. A negative argument means sort in descending order. Thus, minus 2 means sort by field 2 in reverse-alphabetical order.

M-x sort-numeric-fields
Like M-x sort-fields, except the specified field is converted to a number for each line and the numbers are compared. `10' comes before `2' when considered as text, but after it when considered as a number.

M-x sort-columns
Like M-x sort-fields, except that the text within each line used for comparison comes from a fixed range of columns. An explanation is given below.

For example, if the buffer contains:

 
On systems where clash detection (locking of files being edited) is
implemented, XEmacs also checks the first time you modify a buffer
whether the file has changed on disk since it was last visited or
saved.  If it has, you are asked to confirm that you want to change
the buffer.

then if you apply M-x sort-lines to the entire buffer you get:

 
On systems where clash detection (locking of files being edited) is
implemented, XEmacs also checks the first time you modify a buffer
saved.  If it has, you are asked to confirm that you want to change
the buffer.
whether the file has changed on disk since it was last visited or

where the upper case `O' comes before all lower case letters. If you apply instead C-u 2 M-x sort-fields you get:

 
saved.  If it has, you are asked to confirm that you want to change
implemented, XEmacs also checks the first time you modify a buffer
the buffer.
On systems where clash detection (locking of files being edited) is
whether the file has changed on disk since it was last visited or

where the sort keys were `If', `XEmacs', `buffer', `systems', and `the'.

M-x sort-columns requires more explanation. You specify the columns by putting point at one of the columns and the mark at the other column. Because this means you cannot put point or the mark at the beginning of the first line to sort, this command uses an unusual definition of `region': all of the line point is in is considered part of the region, and so is all of the line the mark is in.

For example, to sort a table by information found in columns 10 to 15, you could put the mark on column 10 in the first line of the table, and point on column 15 in the last line of the table, and then use this command. Or you could put the mark on column 15 in the first line and point on column 10 in the last line.

This can be thought of as sorting the rectangle specified by point and the mark, except that the text on each line to the left or right of the rectangle moves along with the text inside the rectangle. See section 9.8 Rectangles.


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26.7 Running Shell Commands from XEmacs

XEmacs has commands for passing single command lines to inferior shell processes; it can also run a shell interactively with input and output to an XEmacs buffer `*shell*'.

M-!
Run a specified shell command line and display the output (shell-command).
M-|
Run a specified shell command line with region contents as input; optionally replace the region with the output (shell-command-on-region).
M-x shell
Run a subshell with input and output through an XEmacs buffer. You can then give commands interactively.
M-x term
Run a subshell with input and output through an XEmacs buffer. You can then give commands interactively. Full terminal emulation is available.

26.7.1 Single Shell Commands  How to run one shell command and return.
26.7.2 Interactive Inferior Shell  Permanent shell taking input via XEmacs.
26.7.3 Shell Mode  Special XEmacs commands used with permanent shell.
26.7.4 Interactive Inferior Shell with Terminal Emulator  An XEmacs window as a terminal emulator.
26.7.5 Term Mode  Special XEmacs commands used in Term mode.
26.7.6 Paging in the terminal emulator  


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26.7.1 Single Shell Commands

M-! (shell-command) reads a line of text using the minibuffer and creates an inferior shell to execute the line as a command. Standard input from the command comes from the null device. If the shell command produces any output, the output goes to an XEmacs buffer named `*Shell Command Output*', which is displayed in another window but not selected. A numeric argument, as in M-1 M-!, directs this command to insert any output into the current buffer. In that case, point is left before the output and the mark is set after the output.

M-| (shell-command-on-region) is like M-! but passes the contents of the region as input to the shell command, instead of no input. If a numeric argument is used to direct output to the current buffer, then the old region is deleted first and the output replaces it as the contents of the region.

Both M-! and M-| use shell-file-name to specify the shell to use. This variable is initialized based on your SHELL environment variable when you start XEmacs. If the file name does not specify a directory, the directories in the list exec-path are searched; this list is initialized based on the PATH environment variable when you start XEmacs. You can override either or both of these default initializations in your init file. See section 27.7 The Init File.

When you use M-! and M-|, XEmacs has to wait until the shell command completes. You can quit with C-g; that terminates the shell command.


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26.7.2 Interactive Inferior Shell

To run a subshell interactively with its typescript in an XEmacs buffer, use M-x shell. This creates (or reuses) a buffer named `*shell*' and runs a subshell with input coming from and output going to that buffer. That is to say, any "terminal output" from the subshell will go into the buffer, advancing point, and any "terminal input" for the subshell comes from text in the buffer. To give input to the subshell, go to the end of the buffer and type the input, terminated by RET.

XEmacs does not wait for the subshell to do anything. You can switch windows or buffers and edit them while the shell is waiting, or while it is running a command. Output from the subshell waits until XEmacs has time to process it; this happens whenever XEmacs is waiting for keyboard input or for time to elapse.

To get multiple subshells, change the name of buffer `*shell*' to something different by using M-x rename-buffer. The next use of M-x shell creates a new buffer `*shell*' with its own subshell. By renaming this buffer as well you can create a third one, and so on. All the subshells run independently and in parallel.

The file name used to load the subshell is the value of the variable explicit-shell-file-name, if that is non-nil. Otherwise, the environment variable ESHELL is used, or the environment variable SHELL if there is no ESHELL. If the file name specified is relative, the directories in the list exec-path are searched (see section Single Shell Commands).

As soon as the subshell is started, it is sent as input the contents of the file `~/.emacs_shellname', if that file exists, where shellname is the name of the file that the shell was loaded from. For example, if you use csh, the file sent to it is `~/.emacs_csh'.

cd, pushd, and popd commands given to the inferior shell are watched by XEmacs so it can keep the `*shell*' buffer's default directory the same as the shell's working directory. These commands are recognized syntactically by examining lines of input that are sent. If you use aliases for these commands, you can tell XEmacs to recognize them also. For example, if the value of the variable shell-pushd-regexp matches the beginning of a shell command line, that line is regarded as a pushd command. Change this variable when you add aliases for `pushd'. Likewise, shell-popd-regexp and shell-cd-regexp are used to recognize commands with the meaning of `popd' and `cd'.

M-x shell-resync-dirs queries the shell and resynchronizes XEmacs' idea of what the current directory stack is. M-x shell-dirtrack-toggle turns directory tracking on and off.

XEmacs keeps a history of the most recent commands you have typed in the `*shell*' buffer. If you are at the beginning of a shell command line and type M-p, the previous shell input is inserted into the buffer before point. Immediately typing M-p again deletes that input and inserts the one before it. By repeating M-p you can move backward through your commands until you find one you want to repeat. You may then edit the command before typing RET if you wish. M-n moves forward through the command history, in case you moved backward past the one you wanted while using M-p. If you type the first few characters of a previous command and then type M-p, the most recent shell input starting with those characters is inserted. This can be very convenient when you are repeating a sequence of shell commands. The variable input-ring-size controls how many commands are saved in your input history. The default is 30.


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26.7.3 Shell Mode

The shell buffer uses Shell mode, which defines several special keys attached to the C-c prefix. They are chosen to resemble the usual editing and job control characters present in shells that are not under XEmacs, except that you must type C-c first. Here is a list of the special key bindings of Shell mode:

RET
At end of buffer send line as input; otherwise, copy current line to end of buffer and send it (send-shell-input). When a line is copied, any text at the beginning of the line that matches the variable shell-prompt-pattern is left out; this variable's value should be a regexp string that matches the prompts that you use in your subshell.
C-c C-d
Send end-of-file as input, probably causing the shell or its current subjob to finish (shell-send-eof).
C-d
If point is not at the end of the buffer, delete the next character just like most other modes. If point is at the end of the buffer, send end-of-file as input, instead of generating an error as in other modes (comint-delchar-or-maybe-eof).
C-c C-u
Kill all text that has yet to be sent as input (kill-shell-input).
C-c C-w
Kill a word before point (backward-kill-word).
C-c C-c
Interrupt the shell or its current subjob if any (interrupt-shell-subjob).
C-c C-z
Stop the shell or its current subjob if any (stop-shell-subjob).
C-c C-\
Send quit signal to the shell or its current subjob if any (quit-shell-subjob).
C-c C-o
Delete last batch of output from shell (kill-output-from-shell).
C-c C-r
Scroll top of last batch of output to top of window (show-output-from-shell).
C-c C-y
Copy the previous bunch of shell input and insert it into the buffer before point (copy-last-shell-input). No final newline is inserted, and the input copied is not resubmitted until you type RET.
M-p
Move backward through the input history. Search for a matching command if you have typed the beginning of a command (comint-previous-input).
M-n
Move forward through the input history. Useful when you are using M-p quickly and go past the desired command (comint-next-input).
TAB
Complete the file name preceding point (comint-dynamic-complete).


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26.7.4 Interactive Inferior Shell with Terminal Emulator

To run a subshell in a terminal emulator, putting its typescript in an XEmacs buffer, use M-x term. This creates (or reuses) a buffer named `*term*' and runs a subshell with input coming from your keyboard and output going to that buffer.

All the normal keys that you type are sent without any interpretation by XEmacs directly to the subshell, as "terminal input." Any "echo" of your input is the responsibility of the subshell. (The exception is the terminal escape character, which by default is C-c. see section 26.7.5 Term Mode.) Any "terminal output" from the subshell goes into the buffer, advancing point.

Some programs (such as XEmacs itself) need to control the appearance on the terminal screen in detail. They do this by sending special control codes. The exact control codes needed vary from terminal to terminal, but nowadays most terminals and terminal emulators (including xterm) understand the so-called "ANSI escape sequences" (first popularized by the Digital's VT100 family of terminal). The term mode also understands these escape sequences, and for each control code does the appropriate thing to change the buffer so that the appearance of the window will match what it would be on a real terminal. Thus you can actually run XEmacs inside an XEmacs Term window!

XEmacs does not wait for the subshell to do anything. You can switch windows or buffers and edit them while the shell is waiting, or while it is running a command. Output from the subshell waits until XEmacs has time to process it; this happens whenever XEmacs is waiting for keyboard input or for time to elapse.

To make multiple terminal emulators, rename the buffer `*term*' to something different using M-x rename-uniquely, just as with Shell mode.

The file name used to load the subshell is determined the same way as for Shell mode.

Unlike Shell mode, Term mode does not track the current directory by examining your input. Instead, if you use a programmable shell, you can have it tell Term what the current directory is. This is done automatically by bash for version 1.15 and later.


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26.7.5 Term Mode

Term uses Term mode, which has two input modes: In line mode, Term basically acts like Shell mode. See section 26.7.3 Shell Mode. In Char mode, each character is sent directly to the inferior subshell, except for the Term escape character, normally C-c.

To switch between line and char mode, use these commands:

findex term-char-mode
C-c C-j
Switch to line mode. Do nothing if already in line mode.

C-c C-k
Switch to char mode. Do nothing if already in char mode.

The following commands are only available in Char mode:

C-c C-c
Send a literal C-c to the sub-shell.

C-c C-x
A prefix command to conveniently access the global C-x commands. For example, C-c C-x o invokes the global binding of C-x o, which is normally `other-window'.


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26.7.6 Paging in the terminal emulator

Term mode has a pager feature. When the pager is enabled, term mode will pause at the end of each screenful.

C-c C-q
Toggles the pager feature: Disables the pager if it is enabled, and vice versa. This works in both line and char modes. If the pager enabled, the mode-line contains the word `page'.

If the pager is enabled, and Term receives more than a screenful of output since your last input, Term will enter More break mode. This is indicated by `**MORE**' in the mode-line. Type a Space to display the next screenful of output. Type ? to see your other options. The interface is similar to the Unix `more' program.


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26.8 Narrowing

Narrowing means focusing in on some portion of the buffer, making the rest temporarily invisible and inaccessible. Cancelling the narrowing and making the entire buffer once again visible is called widening. The amount of narrowing in effect in a buffer at any time is called the buffer's restriction.

C-x n n
Narrow down to between point and mark (narrow-to-region).
C-x n w
Widen to make the entire buffer visible again (widen).

Narrowing sometimes makes it easier to concentrate on a single subroutine or paragraph by eliminating clutter. It can also be used to restrict the range of operation of a replace command or repeating keyboard macro. The word `Narrow' appears in the mode line whenever narrowing is in effect. When you have narrowed to a part of the buffer, that part appears to be all there is. You can't see the rest, can't move into it (motion commands won't go outside the visible part), and can't change it in any way. However, the invisible text is not gone; if you save the file, it will be saved.

The primary narrowing command is C-x n n (narrow-to-region). It sets the current buffer's restrictions so that the text in the current region remains visible but all text before the region or after the region is invisible. Point and mark do not change.

Because narrowing can easily confuse users who do not understand it, narrow-to-region is normally a disabled command. Attempting to use this command asks for confirmation and gives you the option of enabling it; once you enable the command, confirmation will no longer be required. See section 27.5.3 Disabling Commands.

To undo narrowing, use C-x n w (widen). This makes all text in the buffer accessible again.

Use the C-x = command to get information on what part of the buffer you narrowed down. See section 4.8 Cursor Position Information.


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26.9 Hardcopy Output

The XEmacs commands for making hardcopy derive their names from the Unix commands `print' and `lpr'.

M-x print-buffer
Print hardcopy of current buffer using Unix command `print'
(`lpr -p'). This command adds page headings containing the file name and page number.
M-x lpr-buffer
Print hardcopy of current buffer using Unix command `lpr'. This command does not add page headings.
M-x print-region
Like print-buffer, but prints only the current region.
M-x lpr-region
Like lpr-buffer, but prints only the current region.

All the hardcopy commands pass extra switches to the lpr program based on the value of the variable lpr-switches. Its value should be a list of strings, each string a switch starting with `-'. For example, the value could be ("-Pfoo") to print on printer `foo'.


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26.10 Recursive Editing Levels

A recursive edit is a situation in which you are using XEmacs commands to perform arbitrary editing while in the middle of another XEmacs command. For example, when you type C-r inside a query-replace, you enter a recursive edit in which you can change the current buffer. When you exit from the recursive edit, you go back to the query-replace.

Exiting a recursive edit means returning to the unfinished command, which continues execution. For example, exiting the recursive edit requested by C-r in query-replace causes query replacing to resume. Exiting is done with C-M-c (exit-recursive-edit).

You can also abort a recursive edit. This is like exiting, but also quits the unfinished command immediately. Use the command C-] (abort-recursive-edit) for this. See section 27.13 Quitting and Aborting.

The mode line shows you when you are in a recursive edit by displaying square brackets around the parentheses that always surround the major and minor mode names. Every window's mode line shows the square brackets, since XEmacs as a whole, rather than any particular buffer, is in a recursive edit.

It is possible to be in recursive edits within recursive edits. For example, after typing C-r in a query-replace, you might type a command that entered the debugger. In such a case, two or more sets of square brackets appear in the mode line(s). Exiting the inner recursive edit (here with the debugger c command) resumes the query-replace command where it called the debugger. After the end of the query-replace command, you would be able to exit the first recursive edit. Aborting exits only one level of recursive edit; it returns to the command level of the previous recursive edit. You can then abort that one as well.

The command M-x top-level aborts all levels of recursive edits, returning immediately to the top level command reader.

The text you edit inside the recursive edit need not be the same text that you were editing at top level. If the command that invokes the recursive edit selects a different buffer first, that is the buffer you will edit recursively. You can switch buffers within the recursive edit in the normal manner (as long as the buffer-switching keys have not been rebound). While you could theoretically do the rest of your editing inside the recursive edit, including visiting files, this could have surprising effects (such as stack overflow) from time to time. It is best if you always exit or abort a recursive edit when you no longer need it.

In general, XEmacs tries to avoid using recursive edits. It is usually preferable to allow users to switch among the possible editing modes in any order they like. With recursive edits, the only way to get to another state is to go "back" to the state that the recursive edit was invoked from.


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26.11 Dissociated Press

M-x dissociated-press is a command for scrambling a file of text either word by word or character by character. Starting from a buffer of straight English, it produces extremely amusing output. The input comes from the current XEmacs buffer. Dissociated Press writes its output in a buffer named `*Dissociation*', and redisplays that buffer after every couple of lines (approximately) to facilitate reading it.

dissociated-press asks every so often whether to continue operating. Answer n to stop it. You can also stop at any time by typing C-g. The dissociation output remains in the `*Dissociation*' buffer for you to copy elsewhere if you wish.

Dissociated Press operates by jumping at random from one point in the buffer to another. In order to produce plausible output rather than gibberish, it insists on a certain amount of overlap between the end of one run of consecutive words or characters and the start of the next. That is, if it has just printed out `president' and then decides to jump to a different point in the file, it might spot the `ent' in `pentagon' and continue from there, producing `presidentagon'. Long sample texts produce the best results.

A positive argument to M-x dissociated-press tells it to operate character by character, and specifies the number of overlap characters. A negative argument tells it to operate word by word and specifies the number of overlap words. In this mode, whole words are treated as the elements to be permuted, rather than characters. No argument is equivalent to an argument of two. For your againformation, the output goes only into the buffer `*Dissociation*'. The buffer you start with is not changed.

Dissociated Press produces nearly the same results as a Markov chain based on a frequency table constructed from the sample text. It is, however, an independent, ignoriginal invention. Dissociated Press techniquitously copies several consecutive characters from the sample between random choices, whereas a Markov chain would choose randomly for each word or character. This makes for more plausible sounding results and runs faster.

It is a mustatement that too much use of Dissociated Press can be a developediment to your real work. Sometimes to the point of outragedy. And keep dissociwords out of your documentation, if you want it to be well userenced and properbose. Have fun. Your buggestions are welcome.


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26.12 CONX

Besides producing a file of scrambled text with Dissociated Press, you can generate random sentences by using CONX.

M-x conx
Generate random sentences in the *conx* buffer.
M-x conx-buffer
Absorb the text in the current buffer into the conx database.
M-x conx-init
Forget the current word-frequency tree.
M-x conx-load
Load a conx database that has been previously saved with M-x conx-save.
M-x conx-region
Absorb the text in the current buffer into the conx database.
M-x conx-save
Save the current conx database to a file for future retrieval.

Copy text from a buffer using M-x conx-buffer or M-x conx-region and then type M-x conx. Output is continuously generated until you type ^G. You can save the conx database to a file with M-x conx-save, which you can retrieve with M-x conx-load. To clear the database, use M-x conx-init.


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26.13 Other Amusements

If you are a little bit bored, you can try M-x hanoi. If you are considerably bored, give it a numeric argument. If you are very, very bored, try an argument of 9. Sit back and watch.

When you are frustrated, try the famous Eliza program. Just do M-x doctor. End each input by typing RET twice.

When you are feeling strange, type M-x yow.


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26.14 Emulation

XEmacs can be programmed to emulate (more or less) most other editors. Standard facilities can emulate these:

Viper (a vi emulator)
In XEmacs, Viper is the preferred emulation of vi within XEmacs. Viper is designed to allow you to take advantage of the best features of XEmacs while still doing your basic editing in a familiar, vi-like fashion. Viper provides various different levels of vi emulation, from a quite complete emulation that allows almost no access to native XEmacs commands, to an "expert" mode that combines the most useful vi commands with the most useful XEmacs commands.

To start Viper, put the command

 
(viper-mode)

in your init file. See section 27.7 The Init File.

Viper comes with a separate manual that is provided standard with the XEmacs distribution.

EDT (DEC VMS editor)
Turn on EDT emulation with M-x edt-emulation-on. M-x
edt-emulation-off
restores normal Emacs command bindings.

Most of the EDT emulation commands are keypad keys, and most standard Emacs key bindings are still available. The EDT emulation rebindings are done in the global keymap, so there is no problem switching buffers or major modes while in EDT emulation.


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