cal
Unix-like operating system command
cal is a command-line utility on a number of computer operating systems including Unix, Plan 9, Inferno and Unix-like operating systems such as Linux that prints an ASCII calendar of the given month or year. If the user does not specify any... Wikipedia
Example: cal sep 1752
Syntax: cal -smjy13 day month year
Function: Display a simple calendar
Developer(s): Charles Dye
Written in: Plan 9: C; FreeDOS: x86 assembly language