os.time()

os.time ([table])

Returns the current time when called without arguments, or a time representing the local date and time specified by the given table. This table must have fields year, month, and day, and may have fields hour (default is 12), min (default is 0), sec (default is 0), and isdst (default is nil). Other fields are ignored. For a description of these fields, see the os.date function.

The values in these fields do not need to be inside their valid ranges. For instance, if sec is -10, it means -10 seconds from the time specified by the other fields; if hour is 1000, it means +1000 hours from the time specified by the other fields.

The returned value is a number, whose meaning depends on your system. In POSIX, Windows, and some other systems, this number counts the number of seconds since some given start time (the "epoch"). In other systems, the meaning is not specified, and the number returned by time can be used only as an argument to os.date and os.difftime.