| FTOK(3) | Library Functions Manual | FTOK(3) | 
ftok —
#include <sys/types.h>
#include <sys/ipc.h>
key_t
  
  ftok(const
    char *path, int
    id);
ftok() function attempts to create a unique key
  suitable for use with the
  msgget(2),
  semget(2) and
  shmget(2) functions given the
  path of an existing file and a user-selectable
  id.
The specified path must specify an existing file that is accessible to the calling process or the call will fail. Also, note that links to files will return the same key, given the same id.
Only the 8 least significant bits of id are used in the key generation; the rest of the bits are ignored.
ftok() function will return ((key_t)-1) if
  path does not exist or if it cannot be accessed by the
  calling process.
ftok() function conforms to IEEE
  Std 1003.1 (“POSIX.1”).
ftok() function originated with System V and is
  typically used by programs that use the System V IPC routines.
| April 27, 2010 | NetBSD 10.0 |