netbsd man page for ftok

FTOK(3) 						   BSD Library Functions Manual 						   FTOK(3)

NAME
     ftok -- create IPC identifier from path name

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/ipc.h>

     key_t
     ftok(const char *path, int id);

DESCRIPTION
     The 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.

RETURN VALUES
     The ftok() function will return ((key_t)-1) if path does not exist or if it cannot be accessed by the calling process.

SEE ALSO
     msgget(2), semget(2), shmget(2)

STANDARDS
     The ftok() function conforms to IEEE Std 1003.1 (``POSIX.1'').

HISTORY
     The ftok() function originated with System V and is typically used by programs that use the System V IPC routines.

AUTHORS
     Thorsten Lockert <tholo@sigmasoft.com>

BUGS
     The returned key is computed based on the device and inode of the specified path in combination with the given id.  Thus it is quite possible
     for the routine to return duplicate keys given that those fields are not 8- and 16-bit quantities like they were on System V based systems
     where this library routine's ancestor were originally created.

BSD
								  April 27, 2010							       BSD