Gettimedate
getdate <sec> <min> <hour> <mday> <mon> <year> <wday> <yday>
Gets the time and date into gamevars:
<sec> seconds after the minute <min> minutes after the hour <hour> hours since midnight <mday> day of the month <mon> months since January <year> years since 1900 <wday> days since Sunday <yday> days since January
A tutorial on how this command can be used can be viewed here: make an in-game clock