ipc(2) [suse man page]

IPC(2)							     Linux Programmer's Manual							    IPC(2)

NAME

       ipc - System V IPC system calls

SYNOPSIS

       int ipc(unsigned int call, int first, int second, int third,
	       void *ptr, long fifth);

DESCRIPTION

       ipc()  is  a  common  kernel entry point for the System V IPC calls for messages, semaphores, and shared memory.  call determines which IPC
       function to invoke; the other arguments are passed through to the appropriate call.

       User programs should call the appropriate functions by their usual names.  Only standard library implementors and kernel  hackers  need	to
       know about ipc().

CONFORMING TO

       ipc() is Linux-specific, and should not be used in programs intended to be portable.

NOTES

       On  a  few  architectures,  for	example ia64, there is no ipc() system call; instead msgctl(2), semctl(2), shmctl(2), and so on really are
       implemented as separate system calls.

SEE ALSO

       msgctl(2), msgget(2), msgrcv(2), msgsnd(2), semctl(2), semget(2), semop(2), semtimedop(2), shmat(2), shmctl(2), shmdt(2), shmget(2)

COLOPHON

       This page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2007-06-28								    IPC(2)

FTOK(3) 						     Linux Programmer's Manual							   FTOK(3)

NAME

       ftok - convert a pathname and a project identifier to a System V IPC key

SYNOPSIS

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

       key_t ftok(const char *pathname, int proj_id);

DESCRIPTION

       The  ftok()  function  uses the identity of the file named by the given pathname (which must refer to an existing, accessible file) and the
       least significant 8 bits of proj_id (which must be nonzero) to generate a key_t type System V IPC key, suitable	for  use  with	msgget(2),
       semget(2), or shmget(2).

       The  resulting  value  is  the  same for all pathnames that name the same file, when the same value of proj_id is used.	The value returned
       should be different when the (simultaneously existing) files or the project IDs differ.

RETURN VALUE

       On success the generated key_t value is returned.  On failure -1 is returned, with errno indicating the error as  for  the  stat(2)  system
       call.

CONFORMING TO

       POSIX.1-2001.

NOTES

       Under libc4 and libc5 (and under SunOS 4.x) the prototype was:

	      key_t ftok(char *pathname, char proj_id);

       Today proj_id is an int, but still only 8 bits are used.  Typical usage has an ASCII character proj_id, that is why the behavior is said to
       be undefined when proj_id is zero.

       Of course no guarantee can be given that the resulting key_t is unique.	Typically, a best effort attempt combines the given proj_id  byte,
       the  lower  16 bits of the inode number, and the lower 8 bits of the device number into a 32-bit result.  Collisions may easily happen, for
       example between files on /dev/hda1 and files on /dev/sda1.

SEE ALSO

       msgget(2), semget(2), shmget(2), stat(2), svipc(7)

COLOPHON

       This page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2001-11-28								   FTOK(3)