Type Function
Library os.*
Return value String or Table
Revision Current Public Release (2017.3068)
Keywords time, date, format
See also os.time()


Returns a string or a table containing date and time, formatted according to the given string format. When called without arguments, os.date() returns a reasonable date and time representation that depends on the host system and on the current locale (that is, os.date() is equivalent to os.date("%c")).


os.date( [format [, time] ] )
format (optional)

String. If format starts with !, the date is formatted in Coordinated Universal Time. After this optional character, if format is the string *t, then date returns a table with the following fields: year (four digits), month (1-12), day (1-31), hour (0-23), min (0-59), sec (0-61), wday (weekday; Sunday is 1), yday (day of the year), and isdst (daylight saving flag, a boolean). If format is not *t, then os.date() returns the date as a string, formatted according to similar rules as the C function strftime(3).

Code Purpose
%a Abbreviated weekday name
%A Full weekday name
%b Abbreviated month name
%B Full month name
%c Date and time representation appropriate for locale
%d Day of month as decimal number (01 – 31)
%H Hour in 24-hour format (00 – 23)
%I Hour in 12-hour format (01 – 12)
%j Day of year as decimal number (001 – 366)
%m Month as decimal number (01 – 12)
%M Minute as decimal number (00 – 59)
%p Current locale's A.M./P.M. indicator for 12-hour clock
%S Second as decimal number (00 – 59)
%U Week of year as decimal number, with Sunday as first day of week (00 – 53)
%w Weekday as decimal number (0 – 6; Sunday is 0)
%W Week of year as decimal number, with Monday as first day of week (00 – 53)
%x Date representation for current locale
%X Time representation for current locale
%y Year without century, as decimal number (00 – 99)
%Y Year with century, as decimal number
%z, %Z The time-zone name or time zone abbreviation
%% Percent sign

Note that this list is somewhat dependent on the operating system, so don't rely on any additional format items when working on all platforms.

time (optional)

Number. If the time argument is present, this is the time to be formatted (see the os.time() function for a description of this value). Otherwise, os.date() formats the current time.


local date = os.date( "*t" )    -- Returns table of date & time values
print( date.year, date.month )  -- Print year and month
print( date.hour, date.min )    -- Print hour and minutes
print( os.date( "%c" ) )        -- Print time/date string, for example "Thu Oct 23 14:55:02 2010"