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, 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 .