mq_send(3)						     Library Functions Manual							mq_send(3)

NAME

       mq_send - Places a message in the message queue (P1003.1b)

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <mqueue.h>

       int mq_send (
       mqd_t mqdes,
       const char *msg_ptr,
       size_t msg_len,
       unsigned int msg_prio);

PARAMETERS

       mqdes	   Specifies a message queue descriptor.

       *msg_ptr    Specifies a pointer to a buffer containing the message to be sent.

       msg_len	   Indicates the number of bytes of the message to be sent.

       msg_prio    Indicates the priority of the message being sent.

DESCRIPTION

       The  mq_send  function  places a message in the message queue.  This function inserts the message in the queue at the position indicated by
       the msg_prio argument.  A message with a relatively large numeric value for the msg_prio argument has a high priority, and it is  therefore
       inserted before messages with lower values for the msg_prio argument.  This function inserts messages with equal priority into the queue in
       first-in/first-out order.  Thus the function inserts a message with a given priority after already-queued messages that have the same  pri-
       ority.

       If  the message queue is full, and the O_NONBLOCK flag associated with it is not set, the mq_send function blocks until sufficient space in
       the message queue becomes available or until a signal interrupts the mq_send function.

       If two or more processes are waiting to send messages when space becomes available in the queue, the highest-priority process that has been
       waiting the longest sends the message first.

       The mq_send function returns an error if the specified queue is full and the O_NONBLOCK flag is set for that queue.

RETURN VALUES

       On successful completion, the mq_send function returns a value of 0 (zero).

       Otherwise, no message is sent, -1 is returned, and errno is set to indicate the error.

ERRORS

       The mq_send function fails under the following conditions:

       [EAGAIN]       The O_NONBLOCK flag is set in the message queue description associated with mqdes, and the specified message queue is full.

       [EBADF]	      The mqdes argument is not a valid message queue descriptor open for writing.

       [EFAULT]       An internal virtual memory error occurred.

       [EINTR]	      A signal interrupted the call to mq_send.

       [EINVAL]       The value of msg_prio is outside the valid range.

       [EMSGSIZE]     The  specified  message  length,	msg_len, exceeds the message size attribute of the message queue.  Note that a zero-length
		      message is valid.

RELATED INFORMATION

       Functions: mq_receive(3), mq_setattr(3)

       Guide to Realtime Programming delim off

																	mq_send(3)