<mqueue.h>(0P)                                      POSIX Programmer's Manual                                     <mqueue.h>(0P)



NAME
       mqueue.h - message queues (REALTIME)

SYNOPSIS
       #include <mqueue.h>

DESCRIPTION
       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 sigevent structure (as described in <signal.h> ) and 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>,  <sys/types.h>,
       and <time.h>.

       The following sections are informative.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <fcntl.h>,  <signal.h>,  <sys/types.h>,  <time.h>,  the  System  Interfaces  volume  of IEEE Std 1003.1-2001, mq_close(),
       mq_getattr(),  mq_notify(),  mq_open(),  mq_receive(),  mq_send(),   mq_setattr(),   mq_timedreceive(),   mq_timedsend(),
       mq_unlink()

COPYRIGHT
       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,  Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                <mqueue.h>(0P)