Linux calendar command
On Unix-like operating systems, the calendar command displays appointments and provides reminders.
The calendar utility checks the current directory or the directory specified by the CALENDAR_DIR environment variable for a file named calendar and displays lines that begin with either today's date or tomorrow's. On Fridays, events on Friday through Monday are displayed.
calendar [-ab] [-A num] [-B num] [-l num] [-w num] [-f calendarfile] [-t [[[cc]yy]mm]dd]
|-A num||Print lines from today and the next num days forward (in the future). Defaults to one. (same as -l)|
|-a||Process the "calendar" files of all users and mail the results to them. This requires superuser privileges.|
|-B num||Print lines from today and the previous num days backward (in the past).|
|-b||Enforce special date calculation mode for KOI8 calendars.|
|-l||Print lines from today and the next num days forward. Defaults to one. (same as -A)|
|-w num||Print lines from today and the next num days, if today is Friday. Defaults to two, which causes calendar to print entries through the weekend on Fridays.|
|-f calendarfile||Use calendarfile as the default calendar file.|
|-t [[[cc]yy]mm]dd||Act like the specified value is "today" instead of using the current date. If yy is specified, but cc is not, a value for yy between 69 and 99 results in a cc value of 19. Otherwise, a cc value of 20 is used.|
To handle calendars in your national code table, you can specify "LANG=<locale_name>" in the calendar file as early as possible. To handle national Easter names in the calendars, "Easter=<national_name>" (for Catholic Easter) or "Paskha=<national_name>" (for Orthodox Easter) can be used.
A special locale name exists: 'utf-8'. Specifying "LANG=utf-8" indicates that the dates are read using the C locale, and the descriptions are encoded in UTF-8. This setting is usually used for the distributed calendar files. The "CALENDAR" variable can specify the style. Only 'Julian' and 'Gregorian' styles are currently supported. Use "CALENDAR=" to return to the default (Gregorian).
To enforce special date calculation mode for Cyrillic calendars, specify "LANG=<local_name>" and "BODUN=<bodun_prefix>" where <local_name> can be ru_RU.KOI8-R, uk_UA.KOI8-U or by_BY.KOI8-B.
The locale is reset to the user's default for each new file that is read so that locales from one file do not accidentally carry over into another file.
Other lines should begin with a month and day. They may be entered in almost any format, either numeric or as character strings. If proper locale is set, national months and weekdays names can be used. A single asterisk ('*') matches every month. A day without a month matches that day of every week. A month without a day matches the first of that month. Two numbers default to the month followed by the day. Lines with leading tabs default to the last entered date, allowing multiple line specifications for a single date. "Easter" (may be followed by a positive or negative integer) is Easter for this year. "Paskha" (may be followed by a positive or negative integer) is Orthodox Easter for this year. Weekdays may be followed by "-4" ... "+5" (aliases: last, first, second, third, fourth) for moving events like "the last Monday in April".
By convention, dates followed by an asterisk ('*') are not fixed, i.e., change from year to year.
Day descriptions start after the first <tab> character in the line; if the line does not contain a <tab> character, it isn't printed out. If the first character in the line is a <tab> character, it is treated as the continuation of the previous description.
The calendar file is preprocessed by the system's C preprocessor, allowing the inclusion of shared files such as company holidays or meetings. If the shared file is not referenced by a full pathname, the preprocessor searches in the current (or home) directory first, and then in the directory /etc/calendar, and finally in /usr/share/calendar. Empty lines and lines protected by the C commenting syntax (/* ... */) are ignored.
Below is an example set of entries for the calendar file. \t represents a tab character.
LANG=C Easter=Ostern #include <calendar.usholiday> #include <calendar.birthday> 6/15\tJune 15 (if ambiguous, will default to month/day). Jun. 15\tJune 15. 15 June\tJune 15. Thursday\tEvery Thursday. June\tEvery June 1st. 15 *\t15th of every month. May Sun+2\tsecond Sunday in May (Muttertag) 04/SunLast\tlast Sunday in April, \tsummer time in Europe Easter\tEaster Ostern-2\tGood Friday (2 days before Easter) Paskha\tOrthodox Easter
This calendar file includes standard holidays and famous birthdays. For instance, if today were September 24, and you were to run:
...calendar would display the following:
Sep 24 F. Scott Fitzgerald born, 1896
cal — Display a conveniently-formatted calendar from the command line.