The only command is the question mark; however, it does make a difference where you use it.
When entering complex IOS commands, it is common to use the question mark repeatedly
while entering the command, as in the following example:
Router#
clock ?
read-calendar Read the hardware calendar into the clock
set Set the time and date
update-calendar Update the hardware calendar from the clock
Router#
clock set ?
hh:mm:ss Current Time
Router#
clock set 11:15:11 ?
<1-31> Day of the month
MONTH Month of the year
Router#
clock set 11:15:11 25 aug ?
<1993-2035> Year
Router#
clock set 11:15:11 25 aug 2007 ?
Router#
clock set 11:15:11 25 aug 2007
*Aug 25 11:15:11.000: %SYS-6-CLOCKUPDATE: System clock has been updated from
18:52:53 UTC Wed Feb 28 2007 to 11:15:11 UTC Sat Aug 25 2007, configured from
console by cisco on console.