oh, OSX, why don't you have proper guts?

realpath.c

#include <stdlib.h>
#include <stdio.h>

int
main(int argc, char **argv) {
  if (argc < 2) {
    fprintf(stderr, "Missing arg, derp.\n");
    return 1;
  }
  for (int i = 1; i < argc; i++) {
    printf("%s\n", realpath(argv[i], NULL));
  }
  return 0;
}