When invoked with an argument, date sets the current date and time; the argument for setting the date and time is interpreted as follows:
cc
First 2 digits of the year (e.g., 19 for 1999).
yy
Next 2 digits of year (e.g., 99 for 1999).
mm
Numeric month. A number from 01 to 12.
dd
Day, a number from 01 to 31.
hh
Hour, a number from 00 to 23.
mm
Minutes, a number from 00 to 59.
ss
Seconds, a number from 00 to 59.
If the first 2 digits of the year are omitted, they default to 19 if the last two digits of the year are 69 or greater and to 20 if the last two digits of the year are 38 or less (provided the month and year are not later than 0118) and to Wed Dec 31 23:59:59 GMT 1969 otherwise; if all 4 digits of the year are omitted, they default to the current year. If the month or day are omitted, they default to the current month and day, respectively. If the seconds are omitted, they default to 0.
All dates that are not between Jan 1, 1970 and Jan. 18, 2038 are replaced by Wed Dec 31 23:59:59 GMT 1969.
Time changes for Daylight Saving and Standard time, and for leap seconds and years, are handled automatically.
-u Display or set the date in GMT (universal time) instead of local time.
date 2100
date 062100
date 12062100
date 9912062100
date 200212062100