Convert milliseconds timestamp to date from unix command line

Question

I know about

date -d @<timestamp in seconds> 

and

awk '{print strftime("%c", <timestamp in seconds>)}' 

but what if I have milliseconds. Is there trivial way to do this without dropping the final three characters of the millisecond-timestamp (not that dropping characters is difficult, but I would think there'd be a one-step way for such a straightforward task)?

Answer 1

What I have in my bash profile on Mac:

day() {   date -r $(($1 / 1000)) } 

day 1486743904359 returns Fri Feb 10 08:25:04 PST 2017

Answer 2

Instead of dropping characters, you could divide by 1000:

awk '{print strftime("%c", ( <timestamp in milliseconds> + 500 ) / 1000 )}' 

Or:

date -d @$(  echo "(MilliSecondTimeStamp + 500) / 1000" | bc) 

Or (MacOS):

gdate -d @$(  echo "(MilliSecondTimeStamp + 500) / 1000" | bc) 

Edit: Adjusted for the quotients instead of division. Edit2: Thx zeekvfu, fixed.