sys/ipc.h - XSI interprocess communication access structure
The <sys/ipc.h> header is used by three mechanisms for XSI interprocess
communication (IPC): messages, semaphores, and shared memory. All use a
common structure type, ipc_perm, to pass information used in
determining permission to perform an IPC operation.
The ipc_perm structure shall contain 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 Read/write permission.
The uid_t, gid_t, mode_t, and key_t types shall be defined as described
in <sys/types.h> .
Definitions shall be provided for the following constants:
Create entry if key does not exist.
Fail if key exists.
Error if request must wait.
The following shall be declared as a function and may also be defined
as a macro. A function prototype shall be provided.
key_t ftok(const char *, int);
The following sections are informative.
<sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .