sys_msg.h(0P) POSIX Programmer's Manual sys_msg.h(0P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAME
sys/msg.h — XSI message queue structures
SYNOPSIS
#include <sys/msg.h>
DESCRIPTION
The <sys/msg.h> header shall define the following data types through
typedef:
msgqnum_t Used for the number of messages in the message queue.
msglen_t Used for the number of bytes allowed in a message queue.
These types shall be unsigned integer types that are able to store val‐
ues at least as large as a type unsigned short.
The <sys/msg.h> header shall define the following symbolic constant as
a message operation flag:
MSG_NOERROR No error if big message.
The <sys/msg.h> header shall define the msqid_ds structure, which shall
include the following members:
struct ipc_perm msg_perm Operation permission structure.
msgqnum_t msg_qnum Number of messages currently on queue.
msglen_t msg_qbytes Maximum number of bytes allowed on queue.
pid_t msg_lspid Process ID of last msgsnd().
pid_t msg_lrpid Process ID of last msgrcv().
time_t msg_stime Time of last msgsnd().
time_t msg_rtime Time of last msgrcv().
time_t msg_ctime Time of last change.
The <sys/msg.h> header shall define the pid_t, size_t, ssize_t, and
time_t types as described in <sys/types.h>.
The following shall be declared as functions and may also be defined as
macros. Function prototypes shall be provided.
int msgctl(int, int, struct msqid_ds *);
int msgget(key_t, int);
ssize_t msgrcv(int, void *, size_t, long, int);
int msgsnd(int, const void *, size_t, int);
In addition, the <sys/msg.h> header shall include the <sys/ipc.h>
header.
The following sections are informative.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
<sys_ipc.h>, <sys_types.h>
The System Interfaces volume of POSIX.1‐2008, msgctl(), msgget(),
msgrcv(), msgsnd()COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 sys_msg.h(0P)
