cal command

# To display a calendar for the current month:
cal

# To display a calendar for a specific month (1-12 or name):
cal -m month

# To display a calendar for the current year:
cal -y

# To display a calendar for a specific year (4 digits):
cal year

# To display a calendar for a specific month and year:
cal month year

# To display date of Easter (Western Christian churches) in a given year:
ncal -e year