NAME

       zmq_recv - receive a message part from a socket

SYNOPSIS

       int zmq_recv (void *socket, void *buf, size_t len, int flags);

DESCRIPTION

       The zmq_recv() function shall receive a message from the socket referenced by the socket
       argument and store it in the buffer referenced by the buf argument. Any bytes exceeding
       the length specified by the len argument shall be truncated. If there are no messages
       available on the specified socket the zmq_recv() function shall block until the request
       can be satisfied. The flags argument is a combination of the flags defined below: The buf
       argument may be null if len is zero.

       ZMQ_DONTWAIT
           Specifies that the operation should be performed in non-blocking mode. If there are no
           messages available on the specified socket, the zmq_recv() function shall fail with
           errno set to EAGAIN.

   Multi-part messages
       A 0MQ message is composed of 1 or more message parts. 0MQ ensures atomic delivery of
       messages: peers shall receive either all message parts of a message or none at all. The
       total number of message parts is unlimited except by available memory.

       An application that processes multi-part messages must use the ZMQ_RCVMORE
       zmq_getsockopt(3) option after calling zmq_recv() to determine if there are further parts
       to receive.

RETURN VALUE

       The zmq_recv() function shall return number of bytes in the message if successful. Note
       that the value can exceed the value of the len parameter in case the message was
       truncated. If not successful the function shall return -1 and set errno to one of the
       values defined below.

ERRORS

       EAGAIN
           Either the timeout set via the socket-option ZMQ_RCVTIMEO (see zmq_setsockopt(3)) has
           been reached (flag ZMQ_DONTWAIT not set) without being able to read a message from the
           socket or there are no messages available at the moment (flag ZMQ_DONTWAIT set) and
           the operation would block.

       ENOTSUP
           The zmq_recv() operation is not supported by this socket type.

       EFSM
           The zmq_recv() operation cannot be performed on this socket at the moment due to the
           socket not being in the appropriate state. This error may occur with socket types that
           switch between several states, such as ZMQ_REP. See the messaging patterns section of
           zmq_socket(3) for more information.

       ETERM
           The 0MQ context associated with the specified socket was terminated.

       ENOTSOCK
           The provided socket was invalid.

       EINTR
           The operation was interrupted by delivery of a signal before a message was available.

EXAMPLE

       Receiving a message from a socket.

           char buf [256];
           nbytes = zmq_recv (socket, buf, 256, 0);
           assert (nbytes != -1);

SEE ALSO

       zmq_send(3) zmq_getsockopt(3) zmq_setsockopt(3) zmq_socket(7) zmq(7)

AUTHORS

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       Contribution Policy at http://www.zeromq.org/docs:contributing.