ipc.h File

Purpose

Describes the structures that are used by the subroutines that perform interprocess communications operations.

Syntax

#include <sys/ipc.h>

Description

The ipc.h file defines the following symbolic constants, types, and structures:

Symbolic Constants:

IPC_CREAT     create entry if key doesn't exist
IPC_EXCL      fail if key exists
IPC_NOWAIT    error if request must wait
IPC_PRIVATE   private key
IPC_RMID      remove identifier
IPC_SET       set options
IPC_STAT      get options
IPC_ALLO      Centry currently allocated
IPC_R         read or receive permission
IPC_W         write or send permission
IPC_NOERROR   truncates a message if too long
SHM_SIZE      change segment size (shared mem only)

The structure ipc_perm contains the following members:

uid_t                   uid             owner's user id
gid_t                   gid             owner's group id
uid_t                   cuid            creator's user id
gid_t                   cgid            creator's group id
mode_t                  mode            access modes
unsigned short          seq             slot usage sequence number
key_t                   key             key

The types uid_t, gid_t, mode_t, and key_t are as defined in <sys/types.h>.

The following is declared as a function:

key_t         ftok(const char *,  int);