Return a string representing the date and time.
date-string &optional seconds expand-month => string
nil (default) or an integer.
A generalized boolean, default false.
date-string returns a string representing the date and time (including seconds).
If seconds is
nil (the default), string represents the current time. Otherwise, seconds is interpreted as a universal time and string represents that time.
If expand-month is true then the date is written as DD MMM YYYY, with the month in characters. Otherwise, the date is written as YYYY/MM/DD, with the month in digits.
The time follows the date, separated by a space, and is always written as HH:MM:SS.
date-string is intended as a quick way of marking some text as related to some time. For example, the function log-bug-form starts by doing something like:
(format stream "=== Log at ~a ===~2%" (date-string))
LispWorks User Guide and Reference Manual - 20 Sep 2017