nanosecond mtime to console

nano.c

// nano.c: writes nanosecond mtime of first arg to console

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>

#define SEC_TO_NANO 1000000000

int main(int argc, char **argv) {
  if (argc != 2) {
    return 1;
  }

  char *file = argv[1];
  struct stat s;
  stat(file, &s);

  long long out;
  out = ((long long) s.st_mtim.tv_sec) * SEC_TO_NANO;
  out += (long long) s.st_mtim.tv_nsec;

  printf("%lld\n", out);
  return 0;
}