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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/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 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.

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

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

     The include file <sys/types.h> is necessary.

SEE ALSO
     semget(2), shmget(2), compat(5)

HISTORY
     The ftok() function originates 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 minor number and inode of the specified path, in com-bination combination
     bination with the lower 8 bits of the given id.  Thus, it is quite possible for the routine to return
     duplicate keys.

BSD                              July 9, 2009                              BSD