mqueuefs(5) [freebsd man page]

MQUEUEFS(5)						      BSD File Formats Manual						       MQUEUEFS(5)

NAME

     mqueuefs -- POSIX message queue file system

SYNOPSIS

     To link into kernel:

     options P1003_1B_MQUEUE

     To load as a kernel loadable module:

	   kldload mqueuefs

DESCRIPTION

     The mqueuefs module will permit the FreeBSD kernel to support POSIX message queue.  The module contains system calls to manipulate POSIX mes-
     sage queues.  It also contains a file system to implement a view for all message queues of the system.  This helps users to keep track of
     their message queues and make it more easily usable without having to invent additional tools.

     The most common usage is as follows:

	   mount -t mqueuefs null /mnt/mqueue

     where /mnt/mqueue is a mount point.

     It is possible to define an entry in /etc/fstab that looks similar to:

     null    /mnt/mqueue     mqueuefs	     rw      0	     0

     This will mount mqueuefs at the /mnt/mqueue mount point during system boot.  Using /mnt/mqueue as a permanent mount point is not advised as
     its intention has always been to be a temporary mount point.  See hier(7) for more information on FreeBSD directory layout.

     Some common tools can be used on the file system, e.g.: cat(1), chmod(1), chown(8), ls(1), rm(1), etc.  To use only the message queue system
     calls, it is not necessary for user to mount the file system, just load the module or compile it into the kernel.	Manually creating a file,
     for example, ``touch /mnt/mqueue/myqueue'', will create a message queue named myqueue in the kernel, default message queue attributes will be
     applied to the queue.  It is not advised to use this method to create a queue; it is better to use the mq_open(2) system call to create a
     queue as it allows the user to specify different attributes.

     To see the queue's attributes, just read the file:

	   cat /mnt/mqueue/myqueue

SEE ALSO

     mq_open(2), nmount(2), unmount(2), mount(8), umount(8)

AUTHORS

     This manual page was written by David Xu <davidxu@FreeBSD.org>.

BSD
								 November 30, 2005							       BSD

mq_unlink(3RT)															    mq_unlink(3RT)

NAME

       mq_unlink - remove a message queue

SYNOPSIS

       cc [ flag... ] file... -lrt [ library... ]
       #include <mqueue.h>

       int mq_unlink(const char *name);

       The  mq_unlink() function removes the message queue named by the pathname name. After a successful call to mq_unlink() with name, a call to
       mq_open(3RT) with name fails if the flag O_CREAT is not set in flags. If one or more processes have the message queue open when mq_unlink()
       is  called, destruction of the message queue is postponed until all references to the message queue have been closed. Calls to mq_open(3RT)
       to re-create the message queue may fail until the message queue is actually removed. However, the mq_unlink() call need not block until all
       references have been closed; it may return immediately.

       Upon  successful  completion,  mq_unlink() returns 0; otherwise, the named message queue is not changed by this function call, the function
       returns -1 and sets errno to indicate the error.

       The  mq_unlink() function will fail if:

       EACCES		       Permission is denied to unlink the named message queue.

       ENAMETOOLONG	       The length of the name  string  exceeds	 PATH_MAX,  or	a  pathname  component	is  longer  than   NAME_MAX  while
			       _POSIX_NO_TRUNC is in effect.

       ENOENT		       The named message queue, name, does not exist.

       ENOSYS		       mq_unlink() is not supported by the system.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       mqueue.h(3HEAD), mq_close(3RT), mq_open(3RT), attributes(5), standards(5)

       Solaris 2.6 was the first release to support the Asynchronous Input and Output option. Prior to this release, this function always returned
       -1 and set errno to ENOSYS.

								    28 Jun 2002 						    mq_unlink(3RT)