I needed this, because Dendron uses 13-digit epoch time, for created and updated timestamps. While it is not a problem when notes are created from within VSCode (as is expected - since Dendron is a VSCode plugin) - I don’t use VSCode much.

While Dendron has command line tools to create new notes, and notes are markdown only the timestamps are problem.

Hence, the need to create 13-digit epoch time.

date "+%s" can be used to get the epoch time, it only returns 10 digits. Since I don’t care about millisecond precision in my time stamps, I can always add 3 extra 0s at the end, yet it is a hassel.