C: Get date +'%s%N' out of macos...

getSecondsNanoseconds.sh

#!/usr/bin/env sh

cat << EOF > epochInµsec.c
#include <stdio.h>
#include <sys/time.h>

__asm__(".symver realpath,realpath@GLIBC_2.0");

int main(void)
{
  struct timeval time_now;
    gettimeofday(&time_now,NULL);
    int s = time_now.tv_sec;
    int us = time_now.tv_usec;
    //printf("%ld%ld\n",time_now.tv_sec,time_now.tv_usec);
    printf("%10d%06d\n",s,us);
    return 0;
}
EOF

cc -o ts epochInµsec.c

./ts

rm -f ts epochInµsec.c