PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       mq_getattr — get message queue attributes (REALTIME)

SYNOPSIS

       #include <mqueue.h>

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

DESCRIPTION

       The  mq_getattr()  function  shall obtain 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 shall be returned in the mq_attr structure referenced by the mqstat argument.

       Upon return, the following members shall 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 shall 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 shall be set to the current state of the message queue:

       mq_curmsgs
                 The number of messages currently on the queue.

RETURN VALUE

       Upon successful completion, the mq_getattr() function shall return  zero.  Otherwise,  the
       function shall return -1 and set errno to indicate the error.

ERRORS

       The mq_getattr() function may fail if:

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

       The following sections are informative.

EXAMPLES

       See mq_notify().

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mq_notify(), mq_open(), mq_send(), mq_setattr(), msgctl(), msgget(), msgrcv(), msgsnd()

       The Base Definitions volume of POSIX.1‐2017, <mqueue.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .