Answer by user232326 for How to get milliseconds since Unix epoch?

In bash 5+ there is a variable with micro-second granularity: $EPOCHREALTIME.

So:

$ echo "$(( ${EPOCHREALTIME//.} / 1000 ))"1568385422635

Prints time since epoch (1/1/70) in miliseconds.

Failing that, you must use date. Either the GNU date:

echo "$(date +'%s%3N')"

One of the alternatives listed in https://serverfault.com/a/423642/465827

Or brew install coreutils for OS X

Or, if everything else fails, compile (gcc epochInµsec.c) this c program (adjust as needed):

#include <stdio.h>#include <sys/time.h>int main(void){  struct timeval time_now;    gettimeofday(&time_now,NULL);    printf ("%ld secs, %ld usecs\n",time_now.tv_sec,time_now.tv_usec);    return 0;}

Note that calling any external program needs time to be read and loaded from disk, started, run and finally to print the output. That will take several milliseconds. That is the minimum precision that could be achieved with any external tool (including date).