Question

How can I create a hard link to a directory in Mac OS X?

This feature has been added to their file system in Mac OS X v10.5 (Leopard) (for time machine), but I could not find any information on actually using it from the command line.

Answer 1

Unfortunately Apple has crippled the ln command. You can use the following program to create a hard link to a directory:

#include <unistd.h>
#include <stdio.h>

int main(int argc, char* argv[]) {
 if (argc != 3) {
  fprintf(stderr,"Use: hlink <src_dir> <target_dir>\n");
  return 1;
 }
 int ret = link(argv[1],argv[2]);
 if (ret != 0)
  perror("link");
 return ret;
}

Take into account that the hard linked directories may not be in the same parent directory, so you can do this:

$ gcc hlink.c -o hlink
$ mkdir child1
$ mkdir parent
$ ./hlink child1 parent/clone2