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MQ_GETFD_NP(3)		    Library Functions Manual		MQ_GETFD_NP(3)

NAME
       mq_getfd_np -- get a file descriptor for	an open	message	queue descrip-
       tor

SYNOPSIS
       POSIX Real-time Library (librt, -lrt) #include <mqueue.h>

       int
       mq_getfd_np(mqd_t mqd);

DESCRIPTION
       The  mq_getfd_np	function retrieves the underlying file descriptor from
       the given message queue descriptor returned from	mq_open(2).  The  file
       descriptor  is  used by other functions to refer	to that	message	queue.
       The mqd argument	must be	an open	message	queue descriptor.

IMPLEMENTATION NOTES
       FreeBSD implements retrieval or alteration of message queue  attributes
       based  on the file descriptor.  The open	file descriptor	is copied into
       a child after fork(2).  The fstat(2), fchmod(2),	and  fchown(2)	system
       calls are supported for the file	descriptor.

       The  file  descriptor  is  safe to use so long as the message queue de-
       scriptor	remains	open.

RETURN VALUES
       Upon successful completion, the function	returns	a file descriptor.

ERRORS
       The mq_getfd_np function	does not return	any errors.

SEE ALSO
       mq_close(2), mq_open(2),	mqueuefs(4)

HISTORY
       Support for the mq_getfd_np function first appeared in FreeBSD 11.0.

FreeBSD	ports 15.quarterly     December	18, 2025		MQ_GETFD_NP(3)

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