mq_send(3) [osf1 man page]

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)

Check Out this Related Man Page

mq_receive(3)						     Library Functions Manual						     mq_receive(3)

NAME

       mq_receive - Receives the oldest, highest-priority message from the message queue (P1003.1b)

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <mqueue.h>

       ssize_t mq_receive (
       mqd_t mqdes,
       char *msg_ptr,
       size_t msg_len,
       unsigned int *msg_prio);

PARAMETERS

       mqdes	   Specifies a message queue by descriptor.

       *msg_ptr    Specifies a pointer to a buffer to receive the message.

       msg_len	   Specifies the size of the receive buffer identified by the msg_ptr argument.

       *msg_prio   Specifies a pointer to a location to receive the message priority.

DESCRIPTION

       The  mq_receive	function  receives  the oldest, highest-priority message from the message queue. The message is removed from the queue and
       transferred to the buffer pointed to by the msg_ptr argument.

       If the specified message queue is empty and the O_NONBLOCK flag is not set with the mqdes argument, the mq_receive function blocks until  a
       message	is put on the queue or until the mq_receive function is interrupted by a signal.  If more than one process is waiting to receive a
       message when a message arrives at an empty queue, the highest-priority process that has been waiting the longest is selected to receive the
       message.  If the message queue is empty and the O_NONBLOCK flag is set, no message is removed from the queue, and an error is returned.

RETURN VALUES

       On successful completion, the function returns the length of the selected message.

       Otherwise, the function returns the value -1 and sets errno to indicate the error.  No message is removed from the queue.

ERRORS

       The mq_receive function fails under the following conditions:

       [EAGAIN]       O_NONBLOCK was set in the message description associated with mqdes, and the specified message queue is empty.

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

       [EBADMSG]      The implementation has detected a data corruption problem with the message.

       [EFAULT]       An internal virtual memory error occurred.

       [EINTR]	      The mq_receive function was interrupted by a signal.

       [EMSGSIZE]     The specified message buffer size, msg_len, is less than the message size attribute of the message queue.

RELATED INFORMATION

       Functions: mq_send(3)

       Guide to Realtime Programming delim off

																     mq_receive(3)

Linux and UNIX Man Pages

mq_send(3) [osf1 man page]

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