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]

To handle calendars in your national code table you can specify "LANG=" in the calendar file as early as possible. To handle national Easter names in the calendars, "Easter=" (for Catholic Easter) or "Paskha=" (for Orthodox Easter) can be used.

A special locale name exists: 'utf-8'. Specifying "LANG=utf-8" indicates that the dates will be read using the C locale, and the descriptions will be encoded in UTF-8. This setting is usually used for the distributed calendar files. The "CALENDAR" variable can be used to 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 you should specify "LANG=" and "BODUN=" wherecan be ru_RU.KOI8-R, uk_UA.KOI8-U or by_BY.KOI8-B.

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 firstcharacter in the line; if the line does not contain acharacter, it isn't printed out. If the first character in the line is acharacter, 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.