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mq_send(3)
NAME
  mq_send - Places a message in the message queue (P1003.1b)

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    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
  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 priority.

  If the message queue is full, and the O_NONBLOCK flag associated with it is
  not set, the mq_send function blocks until either sufficient space in the
  message queue becomes available or 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 indication 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 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]	 Internal virtual memory error.

  [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)

Index for Section 3

Alphabetical listing for M

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