gettimedate <sec> <min> <hour> <mday> <mon> <year> <wday> <yday>
Gets the local time and date into gamevars. The values in brackets denote inclusive ranges that the individual members can take on.
<sec> seconds after the minute [0, 60] (note the possibility of a leap second) <min> minutes after the hour [0, 59] <hour> hours since midnight [0, 23] <mday> day of the month [1,31] (note that it is 1-based) <mon> months since January [0, 11] <year> years since 0 A.D. <wday> days since Sunday [0, 6] <yday> days since January 1 [0, 365]
A tutorial on how this command can be used can be viewed here: make an in-game clock