Man

Command Section
MQ_GETATTR(2)             FreeBSD System Calls Manual            MQ_GETATTR(2)

NAME
     mq_getattr - get message queue attributes (REALTIME)

LIBRARY
     POSIX Real-time Library (librt, -lrt)

SYNOPSIS
     #include <mqueue.h>

     int
     mq_getattr(mqd_t mqdes, struct mq_attr *mqstat);

DESCRIPTION
     The mq_getattr() system call obtains status information and attributes of
     the message queue and the open message queue description associated with
     the message queue descriptor.

     The mqdes argument specifies a message queue descriptor.

     The results are returned in the mq_attr structure referenced by the
     mqstat argument.

     Upon return, the following members will have the values associated with
     the open message queue description as set when the message queue was
     opened and as modified by subsequent mq_setattr() calls: mq_flags.

     The following attributes of the message queue will be returned as set at
     message queue creation: mq_maxmsg, mq_msgsize.

     Upon return, the following members within the mq_attr structure
     referenced by the mqstat argument will be set to the current state of the
     message queue:

     mq_curmsgs      The number of messages currently on the queue.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     The mq_getattr() system call will fail if:

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

SEE ALSO
     mq_open(2), mq_send(2), mq_setattr(2), mq_timedsend(2)

STANDARDS
     The mq_getattr() system call conforms to IEEE Std 1003.1-2004
     (``POSIX.1'').

HISTORY
     Support for POSIX message queues first appeared in FreeBSD 7.0.

COPYRIGHT
     Portions of this text are reprinted and reproduced in electronic form
     from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology
     -- Portable Operating System Interface (POSIX), The Open Group Base
     Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of
     Electrical and Electronics Engineers, Inc and The Open Group.  In the
     event of any discrepancy between this version and the original IEEE and
     The Open Group Standard, the original IEEE and The Open Group Standard is
     the referee document.  The original Standard can be obtained online at
     http://www.opengroup.org/unix/online.html.

FreeBSD 11.1-RELEASE-p4        February 21, 2014       FreeBSD 11.1-RELEASE-p4
Command Section