Linux and Unix cal command
Calendar for the month and the year.
cal originally appeared in version 6 of AT&T Unix. Since then there have been versions released for BSD, Linux, and other Unix variants. You should check your particular installation's manual for version-specific options. Listed below are the traditional syntax and options for Unix cal.
In general, if no options are given, cal displays the current month at the command line. It's a quick and convenient way to glance at the dates of the month, and can be useful as part of a login script.
cal [options] [[[day] month] year]
|-1||Display a single month. This is the default.|
|-3||Display three months: last month, this month, and next month.|
|-s||Display the calendar using Sunday as the first day of the week.|
|-m||Display Monday as the first day of the week.|
|-j||Display dates of the Julian calendar.|
|-y||Display a calendar for the entire current year.|
Displays the calendar for this month.
cal 12 2000
Displays the calendar for December of the year 2000.