ØMQ Manual - ØMQ/4.0.9


zmq_recv - receive a message part from a socket


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


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:

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


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.


The zmq_recv() operation is not supported by this socket type.
The ØMQ context associated with the specified socket was terminated.
The provided socket was invalid.


Receiving a message from a socket

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

See also


