unix time calculator code example

Example 1: unix time command

time [command] 	#measures time required by following command. For example:
time ls

Example 2: epoch

Epoch timestamp is a unit of measurement for time. It is the number of
seconds elapsed since the countdown has started. 

Beginning epochs per system:
macOS - January 1, 1904
Windows - January 1, 1601
Unix - January 1, 1970