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The Calendar 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.

Mouse-2 in the calendar brings up a menu of operations on a particular date; C-Mouse-3 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 Emacs Lisp Reference Manual, for customization information about the calendar and diary.

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, convert it to other calendars; moving longer time periods is also useful simply to scroll the calendar.

Motion by Standard Lengths of Time

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-forward-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.

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.

Specified 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).

Scrolling in the Calendar

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.

Counting Days

M-= Display the number of days in the current region (calendar-count-days-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.

Miscellaneous Calendar Commands

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

To print the number of days 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. The number of days elapsed includes the selected date. The number of days remaining does not include that date.

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.)

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). Mouse-2 Holidays Display any diary entries 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.

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 Mouse-2 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 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 American holidays and the major Christian, Jewish, and Islamic holidays; also the solstices and equinoxes.

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 American law mandates that daylight savings time begins on the first Sunday in April. In an American locale, Emacs always uses this definition, even though it is wrong for some prior years.

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). Mouse-2 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 Mouse-2 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 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 .emacs 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 The Init File, ~/.emacs.

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 Daylight Savings Time.

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.

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.

Converting To Other Calendars

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

Mouse-2 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 m Display Mayan date for selected day (calendar-print-mayan-date).

If you are using X windows, the easiest way to translate a date into other calendars is to click on it with Mouse-2, 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.

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).

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 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.

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 p 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 Strict Completion) whenever it asks you to type a Mayan name, so you don't have to worry about spelling.

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.

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). Mouse-2 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.

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 Mouse-2 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 fall 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 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. This is the same feature that Outline mode uses to show part of an outline (see section Outline Mode).

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 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 'Calendar/Diary Options' in The Emacs Lisp Reference Manual.

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

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).

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.

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.

Special Diary Entries

In addition to entries based on calendar dates, the diary file can contain special 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 special 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 special 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:

%%(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.

Most generally, special diary entries can perform arbitrary computations to determine when they apply. See section 'Sexp Diary Entries' in The Emacs Lisp Reference Manual.

Appointments

If you have a diary entry for an appointment, and that diary entry begins with a recognizable time of day, Emacs can warn you, several minutes beforehand, that that appointment is pending. Emacs alerts you to the appointment by displaying a message in the mode line.

To enable appointment notification, you must enable the time display feature of Emacs, M-x display-time (see section The Mode Line). You must also add the function appt-make-list to the diary-hook, like this:

(add-hook 'diary-hook 'appt-make-list)

With these preparations done, when you display the diary (either with the d command in the calendar window or with the M-x diary command), it sets up an appointment list of all the diary entries found with recognizable times of day, and reminds you just before each of them.

For example, suppose the diary file contains these lines:

Monday
  9:30am Coffee break
 12:00pm Lunch        

Then on Mondays, after you have displayed the diary, you will be reminded at 9:20am about your coffee break and at 11:50am about lunch.

You can write times in conventional American am/pm style, or 24-hour European/military style. You need not be consistent; your diary file can have a mixture of the two styles.

Emacs updates the appointments list automatically just after midnight. This also displays the next day's diary entries in the diary buffer, unless you set appt-display-diary to nil.

You can also use the appointment notification facility like an alarm clock. The command M-x appt-add adds entries to the appointment list without affecting your diary file. You delete entries from the appointment list with M-x appt-delete.

You can turn off the appointment notification feature at any time by setting appt-issue-message to nil.

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.

These 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)

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, both variables' values are 120.

GNUS

GNUS is an Emacs subsystem for reading and responding to netnews. You can use GNUS to browse through news groups, look at summaries of articles in specific group, and read articles of interest. You can respond to authors or write replies to all the readers of a news group.

This section introduces GNUS and describes several basic features.

To start GNUS, type M-x gnus RET.

GNUS's Three Buffers

GNUS creates and uses three Emacs buffers, each with its own particular purpose and its own major mode.

The Newsgroup buffer contains a list of newsgroups. This is the first buffer that GNUS displays when it starts up. Normally the list contains only the newsgroups to which you subscribe (which are listed in your .newsrc file) and which contain unread articles. Use this buffer to select a specific newsgroup.

The Summary buffer lists the articles in a single newsgroup, including their subjects, their numbers, and who posted them. GNUS creates a Summary buffer for a newsgroup when you select the group in the Newsgroup buffer. Use this buffer to select an article.

The Article buffer displays the text of an article. You rarely need to select this buffer because you can scroll through it while remaining in the Summary buffer.

When GNUS Starts Up

At startup, GNUS reads your .newsrc news initialization file and attempts to communicate with the local news server, which is a repository of news articles. The news server need not be the same computer you are logged in on.

If you start GNUS and connect to the server, but do not see any newsgroups listed in the Newsgroup buffer, type L to get a listing of all the newsgroups. Then type u to unsubscribe from the newsgroups you don't want to read. (You can move point to a particular group using n and p or the usual Emacs commands.)

The first time you start GNUS, it subscribes automatically to every newsgroup that exists. Subsequently, GNUS subscribes automatically to all newly created newsgroups. You can unsubscribe groups with u. You can inhibit automatic subscription by adding the following line to your ~/.newsrc file:

options -n !all !all.all

When you quit GNUS with q, it automatically records in your .newsrc initialization file the subscribed or unsubscribed status of all newsgroups, except for groups you have ``killed''. (You do not need to edit this file yourself, but you may.) When new newsgroups come into existence, GNUS subscribes to them automatically; if you don't want to read them, use u to unsubscribe from them.

Summary of GNUS Commands

Reading news is a two step process:

  1. Choose a newsgroup in the Newsgroup buffer.
  2. Select articles from the Summary buffer. Each article selected is displayed in the Article buffer in a large window, below the Summary buffer in its small window.

Each GNUS buffer has its own special commands, but commands that do the similar things have similar key bindings. Here are commands for the Newsgroup and Summary buffers:

z In the Newsgroup buffer, suspend GNUS. You can return to GNUS later by selecting the Newsgroup buffer and typing g to get newly arrived articles.
q In the Newsgroup buffer, update your .newsrc initialization file and quit GNUS.

In the Summary buffer, exit the current newsgroup and return to the Newsgroup buffer. Thus, typing q twice quits GNUS.

L In the Newsgroup buffer, list all the newsgroups available on your news server (except those you have killed). This may be a long list!

l In the Newsgroup buffer, list only the newsgroups to which you subscribe and which contain unread articles.

u In the Newsgroup buffer, unsubscribe from (or subscribe to) the newsgroup listed in the line that point is on. When you quit GNUS by typing q, GNUS lists in your .newsrc file which groups you have subscribed to. The next time you start GNUS, you won't see this group initially, because GNUS normally displays only subscribed-to groups.

C-k In the Newsgroup buffer, ``kill'' the current line's newsgroup---don't even list it in .newsrc from now on. This affects future GNUS sessions as well as the present session.

When you quit GNUS by typing q, GNUS writes information in the file .newsrc describing all newsgroups except those you have ``killed.''

SPC In the Newsgroup buffer, select the group on the line under the cursor and display the first unread article in that group.

In the Summary buffer,

  • Select the article on the line under the cursor if none is selected.
  • Scroll the text of the selected article (if there is one).
  • Select the next unread article if at the end of the current article.

Thus, you can move through all the articles by repeatedly typing SPC.

DEL In the Newsgroup Buffer, move point to the previous newsgroup containing unread articles.

In the Summary buffer, scroll the text of the article backwards.

n Move point to the next unread newsgroup, or select the next unread article.

p Move point to the previous unread newsgroup, or select the previous unread article.

C-n C-p Move point to the next or previous item, even if it is marked as read. This does not select the article or newsgroup on that line.

s In the Summary buffer, do an incremental search of the current text in the Article buffer, just as if you switched to the Article buffer and typed C-s.

M-s regexp RET In the Summary buffer, search forward for articles containing a match for regexp.

C-c C-s C-n C-c C-s C-s C-c C-s C-d C-c C-s C-a In the Summary buffer, sort the list of articles by number, subject, date, or author.

C-M-n C-M-p In the Summary buffer, read the next or previous article with the same subject as the current article.

Running Shell Commands from Emacs

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

M-! cmd RET Run the shell command line cmd and display the output (shell-command). M-| cmd RET Run the shell command line cmd 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 Emacs buffer. You can then give commands interactively.
  • Single Shell: How to run one shell command and return.
  • Interactive Shell: Permanent shell taking input via Emacs.
  • Shell Mode: Special Emacs commands used with permanent shell.
  • History: Repeating previous commands in a shell buffer.
  • Options: Options for customizing Shell mode.
  • Remote Host: Connecting to another computer.

Single Shell Commands

M-! (shell-command) reads a line of text using the minibuffer executes it as a shell command in a subshell made just for this command. Standard input for the command comes from the null device. If the shell command produces any output, the output goes into an Emacs 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.

If the shell command line ends in &, it runs asynchronously.

M-| (shell-command-on-region) is like M-! but passes the contents of the region as the standard input to the shell command, instead of no input. If a numeric argument is used, meaning insert the output in 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 Emacs is started. 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 environment variable PATH when Emacs is started. Your .emacs file can override either or both of these default initializations.

Both M-! and M-| wait for the shell command to complete. To stop waiting, type C-g to quit; that terminates the shell command with the signal SIGINT---the same signal that C-c normally generates in the shell. Emacs waits until the command actually terminates. If the shell command doesn't stop (because it ignores the SIGINT signal), type C-g again; this sends the command a SIGKILL signal which is impossible to ignore.

Interactive Inferior Shell

To run a subshell interactively, putting its typescript in an Emacs 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 goes 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.

Emacs 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 Emacs has time to process it; this happens whenever Emacs is waiting for keyboard input or for time to elapse.

To make multiple subshells, rename the buffer *shell* to something different using M-x rename-uniquely. Then type M-x shell again to create a new buffer *shell* with its own subshell. If you rename 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; this list is initialized based on the environment variable PATH when Emacs is started. Your .emacs file can override either or both of these default initializations.

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 bash, the file sent to it is ~/.emacs_bash.

cd, pushd and popd commands given to the inferior shell are watched by Emacs 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 Emacs 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. These commands are recognized only at the beginning of a shell command line.

If Emacs gets an error while trying to handle what it believes is a cd, pushd or popd command, it runs the hook shell-set-directory-error-hook (see section Hooks).

If Emacs does not properly track changes in the current directory of the subshell, use the command M-x dirs to ask the shell what its current directory is. This command works for shells that support the most common command syntax; it may not work for unusual shells.

Shell Mode

Shell buffer use 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 Emacs, except that you must type C-c first. Here is a complete 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 (comint-send-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 your shell uses.
TAB Complete the command name or file name before point in the shell buffer (comint-dynamic-complete). TAB also completes history references (see section Shell History References) and environment variable names.

The variable shell-completion-fignore specifies a list of file name extensions to ignore in Shell mode completion. The default setting ignores file names ending in ~, # or %. Other related Comint modes use the variable comint-completion-fignore instead.

M-? Display temporarily a list of the possible completions of the file name before point in the shell buffer (comint-dynamic-list-filename-completions).

C-d Either delete a character or send EOF (comint-delchar-or-maybe-eof). Typed at the end of the shell buffer, C-d sends EOF to the subshell. Typed at any other position in the buffer, C-d deletes a character as usual.

C-c C-a Move to the beginning of the line, but after the prompt if any (comint-bol).

C-c C-u Kill all text pending at end of buffer to be sent as input (comint-kill-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 (comint-interrupt-subjob).

C-c C-z Stop the shell or its current subjob if any (comint-stop-subjob).

C-c C-\ Send quit signal to the shell or its current subjob if any (comint-quit-subjob).

C-c C-o Kill the last batch of output from a shell command (comint-kill-output). This is useful if a shell command spews out lots of output that just gets in the way.

C-c C-r C-M-l Scroll to display the beginning of the last batch of output at the top of the window; also move the cursor there (comint-show-output).

C-c C-e Scroll to put the end of the buffer at the bottom of the window (comint-show-maximum-output).

C-c C-f Move forward across one shell command, but not beyond the current line (shell-forward-command). The variable shell-command-regexp specifies how to recognize the end of a command.

C-c C-b Move backward across one shell command, but not beyond the current line (shell-backward-command).

C-c C-l Display the buffer's history of shell commands in another window (comint-dynamic-list-input-ring).

M-x dirs Ask the shell what its current directory is, so that Emacs can agree with the shell.

M-x send-invisible RET text RET Send text as input to the shell, after reading it without echoing. This is useful when a shell command runs a program that asks for a password.

Alternatively, you can arrange for Emacs to notice password prompts and turn off echoing for them, as follows:

(add-hook `comint-output-filter-functions
          `comint-watch-for-password-prompt)

M-x comint-continue-subjob Continue the shell process. This is useful if you accidentally suspend

M-x comint-strip-ctrl-m Discard all control-m characters from the shell output. The most convenient way to use this command is to make it run automatically when you get output from the subshell. To do that, evaluate this Lisp expression:

(add-hook 'comint-output-filter-functions
          'comint-strip-ctrl-m)

M-x comint-truncate-buffer This command truncates the shell buffer to a certain maximum number of lines, specified by the variable comint-buffer-maximum-size. Here's how to do this automatically each time you get output from the subshell:

(add-hook 'comint-output-filter-functions
          'comint-truncate-buffer)

Shell mode also customizes the paragraph commands so that only shell prompts start new paragraphs. Thus, a paragraph consists of an input command plus the output that follows it in the buffer.

Shell mode is a derivative of Comint mode, a general purpose mode for communicating with interactive subprocesses. Most of the features of Shell mode actually come from Comint mode, as you can see from the command names listed above. The specialization of Shell mode in particular include the choice of regular expression for detecting prompts, the directory tracking feature, and a few user commands.

Other Emacs features that use variants of Comint mode include GUD (see section Running Debuggers Under Emacs) and M-x run-lisp (see section Running an External Lisp).

You can use M-x comint-run to execute any program of your choice in a subprocess using unmodified Comint mode---without the specializations of Shell mode.

Shell Command History

Shell buffers support three ways of repeating earlier commands. You can use the same keys used in the minibuffer; these work much as they do in the minibuffer, inserting text from prior commands while point remains always at the end of the buffer. You can move through the buffer to previous inputs in their original place, then resubmit them or copy them to the end. Or you can use a !-style history reference.

  • Ring: Fetching commands from the history list.
  • Copy: Moving to a command and then copying it.
  • History References: Expanding !-style history references.

Shell History Ring

M-p Fetch the next earlier old shell command.
M-n Fetch the next later old shell command.

M-r regexp RET M-s regexp RET Search backwards or forwards for old shell commands that match regexp.

Shell buffers provide a history of previously entered shell commands. To reuse shell commands from the history, use the editing commands M-p, M-n, M-r and M-s. These work just like the minibuffer history commands except that they operate on the text at the end of the shell buffer, where you would normally insert text to send to the shell.

M-p fetches an earlier shell command to the end of the shell buffer. Successive use of M-p fetches successively earlier shell commands, each replacing any text that was already present as potential shell input. M-n does likewise except that it finds successively more recent shell commands from the buffer.

The history search commands M-r and M-s read a regular expression and search through the history for a matching command. Aside from the choice of which command to fetch, they work just like M-p and M-r. If you enter an empty regexp, these commands reuse the same regexp used last time.

When you find the previous input you want, you can resubmit it by typing RET, or you can edit it first and then resubmit it if you wish.

These commands get the text of previous shell commands from a special history list, not from the shell buffer itself. Thus, editing the shell buffer, or even killing large parts of it, does not affect the history that these commands access.

Some shells store their command histories in files so that you can refer to previous commands from previous shell sessions. Emacs reads the command history file for your chosen shell, to initialize its own command history. The file name is ~/.bash_history for bash, ~/.sh_history for ksh, and ~/.history for other shells.

Shell History Copying

C-c C-p Move point to the previous prompt (comint-previous-prompt).
C-c C-n Move point to the following prompt (comint-next-prompt).

C-c RET Copy the input command which point is in, inserting the copy at the end of the buffer (comint-copy-old-input). This is useful if you move point back to a previous command. After you copy the command, you can submit the copy as input with RET. If you wish, you can edit the copy before resubmitting it.

Moving to a previous input and then copying it with C-c RET produces the same results---the same buffer contents---that you would get by using M-p enough times to fetch that previous input from the history list. However, C-c RET copies the text from the buffer, which can be different from what is in the history list if you edit the input text in the buffer after it has been sent.

Shell History References

Various shells including csh and bash support history references that begin with ! and ^. Shell mode can understands these constructs and perform the history substitution for you. If you insert a history reference and type TAB, this searches the input history for a matching command, performs substitution if necessary, and places the result in the buffer in place of the history reference. For example, you can fetch the most recent command beginning with mv with ! m v TAB. You can edit the command if you wish, and then resubmit the command to the shell by typing RET.

History references take effect only following a shell prompt. The variable shell-prompt-pattern specifies how to recognize a shell prompt. Comint modes in general use the variable comint-prompt-regexp to specify how to find a prompt; Shell mode uses shell-prompt-pattern to set up the local value of comint-prompt-regexp.

Shell mode can optionally expand history references in the buffer when you send them to the shell. To request this, set the variable comint-input-autoexpand to input.

You can make SPC perform history expansion by binding SPC to the command comint-magic-space.

Shell Mode Options

If the variable comint-scroll-to-bottom-on-input is non-nil, insertion and yank commands scroll the selected window to the bottom before inserting.

If comint-scroll-show-maximum-output is non-nil (which is the default), then scrolling due to arrival of output tries to place the last line of text at the bottom line of the window, so as to show as much useful text as possible. (This mimics the scrolling behavior of many terminals.)

By setting comint-scroll-to-bottom-on-output, you can opt for having point jump to the end of the buffer whenever output arrives---no matter where in the buffer point was before. If the value is this, point jumps in the selected window. If the value is all, point jumps in each window that shows the comint buffer. If the value is other, point jumps in all nonselected windows that show the current buffer. The default value is nil, which means point does not jump to the end.

The variable comint-input-ignoredups controls whether successive identical inputs are stored in the input history. A non-nil value means to omit an input that is the same as the previous input. The default is nil, which means to store each input even if it is equal to the previous input.

Three variables customize file name completion. The variable comint-completion-addsuffix controls whether completion inserts a space or a slash to indicate a fully completed file or directory name (non-nil means do insert a space or slash). comint-completion-recexact, if non-nil, directs TAB to choose the shortest possible completion if the usual Emacs completion algorithm cannot add even a single character. comint-completion-autolist, if non-nil, says to list all the possible completions whenever completion is not exact.

The command comint-dynamic-complete-variable does variable name completion using the environment variables as set within Emacs. The variables controlling file name completion apply to variable name completion too. This command is normally available through the menu bar.

Command completion normally considers only executable files. If you set shell-command-execonly to nil, it considers nonexecutable files as well.

You can configure the behavior of pushd. Variables control whether pushd behaves like cd if no argument is given (shell-pushd-tohome), pop rather than rotate with a numeric argument (shell-pushd-dextract), and only add directories to the directory stack if they are not already on it (shell-pushd-dunique). The values you choose should match the underlying shell, of course.

Remote Host Shell

Emacs provides two commands for logging in to another computer and communicating with it through an Emacs buffer.

M-x telnet RET hostname RET Set up a Telnet connection to the computer named hostname. M-x rlogin RET hostname RET Set up an Rlogin connection to the computer named hostname.

Use M-x telnet to set up a Telnet connection to another computer. (Telnet is the standard Internet protocol for remote login.) It reads the host name of the other computer as an argument with the minibuffer. Once the connection is established, talking to the other computer works like talking to a subshell: you can edit input with the usual Emacs commands, and send it a line at a time by typing RET. The output is inserted in the Telnet buffer interspersed with the input.

Use M-x rlogin to set up an Rlogin connection. Rlogin is another remote login communication protocol, essentially much like the Telnet protocol but incompatible with it, and supported only by certain systems. Rlogin's advantages are that you can arrange not to have to give your user name and password when communicating between two machines you frequently use, and that you can make an 8-bit-clean connection. (To do that in Emacs, set rlogin-explicit-args to ("-8") before you run Rlogin.)

M-x rlogin sets up the default file directory of the Emacs buffer to access the remote host via FTP (see section File Names), and it tracks the shell commands that change the current directory just like Shell mode.

Using Emacs as a Server

Various programs such as mail can invoke your choice of editor to edit a particular piece of text, such as a message that you are sending. By convention, most of these programs use the environment variable EDITOR to specify which editor to run. If you set EDITOR to emacs, they invoke Emacs---but in an inconvenient fashion, by starting a new, separate Emacs process. This is inconvenient because it takes time and because the new Emacs process doesn't share the buffers in the existing Emacs process.

You can arrange to use your existing Emacs process as the editor for programs like mail by using the Emacs client and Emacs server programs. Here is how.

First, the preparation. Within Emacs, call the function server-start. (Your .emacs file can do this automatically if you add the expression (server-start) to it.) Then, outside Emacs, set the EDITOR environment variable to emacsclient. (Note that some programs use a different environment variable; for example, to make TeX use emacsclient, you should set the TEXEDIT environment variable to emacsclient +%d %s.)

Then, whenever any program invokes your specified EDITOR program, the effect is to send a message to your principal Emacs telling it to visit a file. (That's what the program emacsclient does.) Emacs displays the buffer immediately and you can immediately begin editing it.

When you've finished editing that buffer, type C-x # (server-edit). This saves the file and sends a message back to the emacsclient program telling it to exit. The programs that use EDITOR wait for the ``editor'' (actually, emacsclient) to exit. C-x # also checks for other pending external requests to edit various files, and selects the next such file.

You can switch to a server buffer manually if you wish; you don't have to arrive at it with C-x #. But C-x # is the only way to say that you are ``finished'' with one.

If you set the variable server-window to a window or a frame, C-x # displays the server buffer in that window or in that frame.

While mail or another application is waiting for emacsclient to finish, emacsclient does not read terminal input. So the terminal that mail was using is effectively blocked for the duration. In order to edit with your principal Emacs, you need to be able to use it without using that terminal. There are two ways to do this:

  • Using a window system, run mail and the principal Emacs in two separate windows. While mail is waiting for emacsclient, the window where it was running is blocked, but you can use Emacs by switching windows.
  • Use Shell mode in Emacs to run the other program such as mail; then, emacsclient blocks only the subshell under Emacs, and you can still use Emacs to edit the file.

Some programs write temporary files for you to edit. After you edit the temporary file, the program reads it back and deletes it. If the Emacs server is later asked to edit the same file name, it should assume this has nothing to do with the previous occasion for that file name. The server accomplishes this by killing the temporary file's buffer when you finish with the file. Use the variable server-temp-file-regexp to specify which files are temporary in this sense; its value should be a regular expression that matches file names that are temporary.

Hardcopy Output

The Emacs commands for making hardcopy let you print either an entire buffer or just part of one, either with or without page headers. See also the hardcopy commands of Dired (see section Miscellaneous File Operations) and the diary (see section Commands Displaying Diary Entries).

M-x print-buffer Print hardcopy of current buffer with page headings containing the file name and page number. M-x lpr-buffer Print hardcopy of current buffer without page headings. makes no page headings. M-x print-region Like print-buffer but print only the current region. M-x lpr-region Like lpr-buffer but print only the current region.

The hardcopy commands (aside from the Postscript 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 an option starting with -. For example, to use a printer named nearme, set lpr-switches like this:

(setq lpr-switches '("-Pnearme"))

The variable lpr-header-switches similarly specifies the extra switches to use to make page headers.

Postscript Hardcopy

These commands convert buffer contents to Postscript, either printing it or leaving it in another Emacs buffer.

M-x ps-print-buffer Print hardcopy of the current buffer in Postscript form. M-x ps-print-region Print hardcopy of the current region in Postscript form. M-x ps-print-buffer-with-faces Print hardcopy of the current buffer in Postscript form, showing the faces used in the text by means of Postscript features. M-x ps-print-region-with-faces Print hardcopy of the current region in Postscript form, showing the faces used in the text. M-x ps-spool-buffer Generate Postscript for the current buffer text. M-x ps-spool-region Generate Postscript for the current region. M-x ps-spool-buffer-with-faces Generate Postscript for the current buffer, showing the faces used. M-x ps-spool-region-with-faces Generate Postscript for the current region, showing the faces used.

The Postscript commands, ps-print-buffer and ps-print-region, print buffer contents in Postscript form. One command prints the entire buffer; the other, just the region. The corresponding -with-faces commands, ps-print-buffer-with-faces and ps-print-region-with-faces, use Postscript features to show the faces (fonts and colors) in the text properties of the text being printed.

All four of the commands above use the variables ps-lpr-command and ps-lpr-switches to specify how to print the output. ps-lpr-command specifies the command name to run, and ps-lpr-switches specifies command line options to use. If you don't set these variables yourself, they take their initial values from lpr-command and lpr-switches.

The variable ps-print-header controls whether these commands add header lines to each page---set it to nil to turn headers off. You can turn off color processing by setting ps-print-color-p to nil. Many other customization variables for these commands are defined and described in the Lisp file ps-print.el.

The commands whose names have spool instead of print generate the Postscript output in an Emacs buffer instead of sending it to the printer.

Sorting Text

Emacs provides several commands for sorting text in the 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 into the order determined by the sort keys. The records are ordered so that their keys are in alphabetical order, or, for numeric sorting, in numeric order. In alphabetic sorting, all upper case letters `A' through `Z' come before lower case `a', in accord with the ASCII character sequence.

The various sort commands differ in how they divide the text into sort records and in which part of each record is used 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 numeric argument means sort into 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 numeric argument means sort into 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 numeric argument means sort into 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.

Specify which field to sort by with a numeric argument: 1 to sort by field 1, etc. A negative argument means count fields from the right instead of from the left; thus, minus 1 means sort by the last field. If several lines have identical contents in the field being sorted, they keep same relative order that they had in the original buffer.

A negative argument means count fields from the right (from the end of the line).

M-x sort-numeric-fields Like M-x sort-fields except the specified field is converted to an integer 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. See below for an explanation.

M-x reverse-region Reverse the order of the lines in the region. This is useful for sorting into descending order by fields or columns, since those sort commands do not have a feature for doing that.

For example, if the buffer contains this:

On systems where clash detection (locking of files being edited) is
implemented, Emacs 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.

applying M-x sort-lines to the entire buffer produces this:

On systems where clash detection (locking of files being edited) is
implemented, Emacs 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 sorts before all lower case letters. If you use C-u 2 M-x sort-fields instead, you get this:

implemented, Emacs 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.
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 Emacs, If, 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, as well as all the lines in between.

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 run sort-columns. Equivalently, you could run it with 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 Rectangles.

Many of the sort commands ignore case differences when comparing, if sort-fold-case is non-nil.

Narrowing

Narrowing means focusing in on some portion of the buffer, making the rest temporarily inaccessible. The portion which you can still get to is called the accessible portion. Canceling the narrowing, which makes the entire buffer once again accessible, is called widening. The amount of narrowing in effect in a buffer at any time is called the buffer's restriction.

Narrowing can make 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.

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

When you have narrowed down to a part of the buffer, that part appears to be all there is. You can't see the rest, you can't move into it (motion commands won't go outside the accessible part), you can't change it in any way. However, it is not gone, and if you save the file all the inaccessible text will be saved. The word Narrow appears in the mode line whenever narrowing is in effect.

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 accessible but all text before the region or after the region is inaccessible. Point and mark do not change.

Alternatively, use C-x n p (narrow-to-page) to narrow down to the current page. See section Pages, for the definition of a page.

The way to cancel narrowing is to widen with C-x n w (widen). This makes all text in the buffer accessible again.

You can get information on what part of the buffer you are narrowed down to using the C-x = command. See section Cursor Position Information.

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; if you enable the command, confirmation will no longer be required for it. See section Disabling Commands.

Two-Column Editing

Two-column mode lets you conveniently edit two side-by-side columns of text. It uses two side-by-side windows, each showing its own buffer.

There are three ways to enter two-column mode:

C-x 6 2 Enter two-column mode with the current buffer on the left, and on the right, a buffer whose name is based on the current buffer's name (tc-two-columns). If the right-hand buffer doesn't already exist, it starts out empty; the current buffer's contents are not changed.
This command is appropriate when the current buffer contains just one column and you want to add another column.

C-x 6 s Split the current buffer, which contains two-column text, into two buffers, and display them side by side (tc-split). The current buffer becomes the left-hand buffer, but the text in the right-hand column is moved into the right-hand buffer. The current column specifies the split point. Splitting starts with the current line and continues to the end of the buffer.

This command is appropriate when you have a buffer that already contains two-column text, and you wish to separate the columns temporarily.

C-x 6 b buffer RET Enter two-column mode using the current buffer as the left-hand buffer, and using buffer buffer as the right-hand buffer (tc-associate-buffer).

C-x 6 s looks for a column separator which is a string that appears on each line between the two columns. You can specify the width of the separator with a numeric argument to C-x 6 s; that many characters, before point, constitute the separator string. By default, the width is 1, so the column separator is the character before point.

When a line has the separator at the proper place, C-x 6 s puts the text after the separator into the right-hand buffer, and deletes the separator. Lines that don't have the column separator at the proper place remain unsplit; they stay in the left-hand buffer, and the right-hand buffer gets an empty line to correspond. (This is the way to write a line that spans both columns while in two-column mode: write it in the left-hand buffer, and put an empty line in the right-hand buffer.)

It's not a good idea to use ordinary scrolling commands during two-column editing, because that separates the two parts of each split line. Instead, use these special scroll commands:

C-x 6 SPC Scroll both buffers up, in lock step (tc-scroll-up). C-x 6 DEL Scroll both buffers down, in lock step (tc-scroll-down). C-x 6 C-l Recenter both buffers, in lock step (tc-recenter).

When you have edited both buffers as you wish, merge them with C-x 6 1 (tc-merge). This copies the text from the right-hand buffer as a second column in the other buffer. To go back to two-column editing, use C-x 6 s.

Use C-x 6 d to disassociate the two buffers, leaving each as it stands (tc-dissociate). If the other buffer, the one not current when you type C-x 6 d, is empty, C-x 6 d kills it.

Editing Binary Files

There is a special major mode for editing binary files: Hexl mode. To use it, use M-x hexl-find-file instead of C-x C-f to visit the file. This command converts the file's contents to hexadecimal and lets you edit the translation. When you save the file, it is converted automatically back to binary.

You can also use M-x hexl-mode to translate an existing buffer into hex. This is useful if you visit a file normally and then discover it is a binary file.

Ordinary text characters overwrite in Hexl mode. This is to reduce the risk of accidentally spoiling the alignment of data in the file. There are special commands for insertion. Here is a list of the commands of Hexl mode:

C-M-d Insert a byte with a code typed in decimal.
C-M-o Insert a byte with a code typed in octal.

C-M-x Insert a byte with a code typed in hex.

C-x [ Move to the beginning of a 1k-byte ``page''.

C-x ] Move to the end of a 1k-byte ``page''.

M-g Move to an address specified in hex.

M-j Move to an address specified in decimal.

C-c C-c Leave Hexl mode, going back to the major mode this buffer had before you invoked hexl-mode.

Saving Emacs Sessions

You can use the Desktop library to save the state of Emacs from one session to another. Saving the state means that Emacs starts up with the same set of buffers, major modes, buffer positions, and so on that the previous Emacs session had.

To use Desktop, you should first add these lines to your .emacs file, preferably at or near the end:

(load "desktop")
(desktop-load-default)
(desktop-read)

Then, to enable state saving in a particular Emacs session, use the command M-x desktop-save. Once you have done this, the state of this Emacs session will be saved when you exit Emacs.

In order for Emacs to recover the state from a previous session, you must start it with the same current directory as you used when you started the previous session.

The variable desktop-files-not-to-save controls which files are excluded from state saving. Its value is a regular expression that matches the files to exclude. By default, remote (ftp-accessed) files are excluded; this is because visiting them again in the subsequent session would be slow. If you want to include these files in state saving, set desktop-files-not-to-save to "^$".

Recursive Editing Levels

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

Exiting the recursive edit means returning to the unfinished command, which continues execution. The command to exit is C-M-c (exit-recursive-edit).

You can also abort the recursive edit. This is like exiting, but also quits the unfinished command immediately. Use the command C-] (abort-recursive-edit) to do this. See section 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 this, in the same way, since being in a recursive edit is true of Emacs as a whole rather than any particular window or buffer.

It is possible to be in recursive edits within recursive edits. For example, after typing C-r in a query-replace, you may type a command that enters the debugger. This begins a recursive editing level for the debugger, within the recursive editing level for C-r. Mode lines display a pair of square brackets for each recursive editing level currently in progress.

Exiting the inner recursive edit (such as, with the debugger c command) resumes the command running in the next level up. When that command finishes, you can then use C-M-c to exit another recursive editing level, and so on. Exiting applies to the innermost level only. Aborting also gets out of only one level of recursive edit; it returns immediately to the command level of the previous recursive edit. If you wish, you can then abort the next recursive editing level.

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

The text being edited inside the recursive edit need not be the same text that you were editing at top level. It depends on what the recursive edit is for. If the command that invokes the recursive edit selects a different buffer first, that is the buffer you will edit recursively. In any case, you can switch buffers within the recursive edit in the normal manner (as long as the buffer-switching keys have not been rebound). You could probably do all the rest of your editing inside the recursive edit, visiting files and all. But this could have surprising effects (such as stack overflow) from time to time. So remember to exit or abort the recursive edit when you no longer need it.

In general, we try to minimize the use of recursive editing levels in GNU Emacs. This is because they constrain you to ``go back'' in a particular order--from the innermost level toward the top level. When possible, we present different activities in separate buffers so that you can switch between them as you please. Some commands switch to a new major mode which provides a command to switch back. These approaches give you more flexibility to go back to unfinished tasks in the order you choose.

Emulation

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

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.

vi (Berkeley editor) Viper is the newest emulator for vi. It implements several levels of emulation; level 1 is closest to vi itself, while level 5 departs somewhat from strict emulation to take advantage of the capabilities of Emacs. To invoke Viper, type M-x viper-mode; it will guide you the rest of the way and ask for the emulation level.

vi (another emulator) M-x vi-mode enters a major mode that replaces the previously established major mode. All of the vi commands that, in real vi, enter ``input'' mode are programmed instead to return to the previous major mode. Thus, ordinary Emacs serves as vi's ``input'' mode.

Because vi emulation works through major modes, it does not work to switch buffers during emulation. Return to normal Emacs first.

If you plan to use vi emulation much, you probably want to bind a key to the vi-mode command.

vi (alternate emulator) M-x vip-mode invokes another vi emulator, said to resemble real vi more thoroughly than M-x vi-mode. ``Input'' mode in this emulator is changed from ordinary Emacs so you can use ESC to go back to emulated vi command mode. To get from emulated vi command mode back to ordinary Emacs, type C-z.

This emulation does not work through major modes, and it is possible to switch buffers in various ways within the emulator. It is not so necessary to assign a key to the command vip-mode as it is with vi-mode because terminating insert mode does not use it.

For full information, see the long comment at the beginning of the source file, which is lisp/vip.el in the Emacs distribution.

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 Emacs buffer. Dissociated Press writes its output in a buffer named *Dissociation*, and redisplays that buffer after every couple of lines (approximately) so you can read the output as it comes out.

Dissociated Press asks every so often whether to continue generating output. 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'

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.

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.

If you want a little more personal involvement, try M-x gomoku, which plays the game Go Moku with you.

M-x blackbox and M-x mpuz are two kinds of puzzles. blackbox challenges you to determine the location of objects inside a box by tomography. mpuz displays a multiplication puzzle with letters standing for digits in a code that you must guess---to guess a value, type a letter and then the digit you think it stands for.

M-x dunnet runs an adventure-style exploration game, which is a bigger sort of puzzle.

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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