|| FreeBSD Library Functions Manual
create IPC identifier from path name
Standard C Library (libc, -lc)
() function attempts to create a unique key suitable for use with the
functions given the
of an existing file and a user-selectable
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.
ftok() function originates with System V and is typically used by programs that use the System V IPC routines.
BUGS The returned key is computed based on the device minor number and inode of the specified
path in combination with the lower 8 bits of the given
id. Thus it is quite possible for the routine to return duplicate keys.