FTOK(3) BSD Library Functions Manual FTOK(3)NAMEftok — create IPC identifier from path name
Standard C Library (libc, -lc)
ftok(const char *path, int id);
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.
The ftok() function will return -1 if path does not exist or if it cannot
be accessed by the calling process.
SEE ALSOsemget(2), shmget(2), msgget(2)HISTORY
The ftok() function originates with System V and is typically used by
programs that use the System V IPC routines.
Thorsten Lockert ⟨email@example.com⟩
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.
BSD July 9, 2009 BSD