If no parameters are specified, the current month's calendar is
displayed.
A single parameter specifies the year and optionally the month
in ISO format:
``cal
2007-12
''
Two parameters denote the month (1 - 12) and year.
Note that the century must be included in the year.
A year starts on Jan 1.
In view of the chaotic way the Gregorian calendar was adopted throughout the world in the years between 1582 and 1928 make sure to take into account the date of the Gregorian Reformation in your region if you are checking a calendar for a very old date.
cal has a decent built-in list of Gregorian Reform dates and the names of the countries where the reform was adopted:
Italy Oct. 5, 1582 Denmark Feb. 19, 1700
Spain Oct. 5, 1582 Great Britain Sep. 3, 1752
Portugal Oct. 5, 1582 Sweden Feb. 18, 1753
Poland Oct. 5, 1582 Finland Feb. 18, 1753
France Dec. 12, 1582 Japan Dec. 20, 1872
Luxembourg Dec. 22, 1582 China Nov. 7, 1911
Netherlands Dec. 22, 1582 Bulgaria Apr. 1, 1916
Bavaria Oct. 6, 1583 U.S.S.R. Feb. 1, 1918
Austria Jan. 7, 1584 Serbia Jan. 19, 1919
Switzerland Jan. 12, 1584 Romania Jan. 19, 1919
Hungary Oct. 22, 1587 Greece Mar. 10, 1924
Germany Feb. 19, 1700 Turkey Dec. 19, 1925
Norway Feb. 19, 1700 Egypt Sep. 18, 1928
The country known as Great Britain can also be referred to as England since that has less letters and no spaces in it. This is meant only as a measure of expediency, not as a possible slight to anyone involved.
AT&T UNIX
.