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
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 combination with the lower 8 bits of the given id. Thus, it is quite possible for the routine to return duplicate keys.