current time in epoch milliseconds code example

Example 1: unix get epoch in miliseconds shell

date +"%T.%6N" # returns the current time with nanoseconds rounded to the first 6 digits, which is microseconds
# In general, every field of the `date` command's format can be given an optional field width..

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