mqueue.h - Man Page

message queues (REALTIME)


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.


#include <mqueue.h>


The <mqueue.h> header shall define the mqd_t type, which is used for message queue descriptors. This is not an array type.

The <mqueue.h> header shall define the pthread_attr_t, size_t, and ssize_t types as described in <sys/types.h>.

The <mqueue.h> header shall define the struct timespec structure as described in <time.h>.

The tag sigevent shall be declared as naming an incomplete structure type, the contents of which are described in the <signal.h> header.

The <mqueue.h> header shall define the mq_attr structure, which is used in getting and setting the attributes of a message queue. Attributes are initially set when the message queue is created. An mq_attr structure shall have at least the following fields:

long    mq_flags    Message queue flags.
long    mq_maxmsg   Maximum number of messages.
long    mq_msgsize  Maximum message size.
long    mq_curmsgs  Number of messages currently queued.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

int      mq_close(mqd_t);
int      mq_getattr(mqd_t, struct mq_attr *);
int      mq_notify(mqd_t, const struct sigevent *);
mqd_t    mq_open(const char *, int, ...);
ssize_t  mq_receive(mqd_t, char *, size_t, unsigned *);
int      mq_send(mqd_t, const char *, size_t, unsigned);
int      mq_setattr(mqd_t, const struct mq_attr *restrict,
             struct mq_attr *restrict);
ssize_t  mq_timedreceive(mqd_t, char *restrict, size_t,
             unsigned *restrict, const struct timespec *restrict);
int      mq_timedsend(mqd_t, const char *, size_t, unsigned,
             const struct timespec *);
int      mq_unlink(const char *);

Inclusion of the <mqueue.h> header may make visible symbols defined in the headers <fcntl.h>, <signal.h>, and <time.h>.

The following sections are informative.

Application Usage




Future Directions


See Also

<fcntl.h>, <signal.h>, <sys_types.h>, <time.h>

The System Interfaces volume of POSIX.1-2017, mq_close(), mq_getattr(), mq_notify(), mq_open(), mq_receive(), mq_send(), mq_setattr(), mq_unlink()

Referenced By

mq_close(3p), mq_getattr(3p), mq_notify(3p), mq_open(3p), mq_receive(3p), mq_send(3p), mq_setattr(3p), mq_unlink(3p).

2017 IEEE/The Open Group POSIX Programmer's Manual