Gettimedate

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