[gdevenyi]

Doesn't 'date' do this on the commabd line?

[donio]

date +'%F %H:%M:%S.%N' -d @1677954553.2134567654

Adjust the format as desired.

Or if there is the number of nsecs rather than the fraction:

date +'%F %H:%M:%S.%N' -d @$(dc -e '9k 16779545532134567654 10 9^/p')

The dc stuff is RPN, k sets the precision, p is print.

[watersb]

I got in the habit of using %T for Time (of day), as a shorthand for %H:%M:%S, but I can't recall how portable that is.

  date "+%F %T.%N"

[heyoni]

gdate if you’re using home brew on Mac

[Y_Y]

If you stopped people from posting about their amazing new project that replicates standard functionality from classic unix tools we'd have very little left.

[heyoni]

Cool. Let’s stop people from discussing these ‘amazing’ projects then. That sounds productive.