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.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in
.\" the documentation and/or other materials provided with the
.\" distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd November 30, 2005
.Dt MQUEUEFS 5
.Os
.Sh NAME
.Nm mqueuefs
.Nd POSIX message queue file system
.Sh SYNOPSIS
To link into kernel:
.Pp
.Cd "options P1003_1B_MQUEUE"
.Pp
To load as a kernel loadable module:
.Pp
.Dl "kldload mqueuefs"
.Sh DESCRIPTION
The
.Nm
module will permit the
.Fx
kernel to support
.Tn POSIX
message queue.
The module contains system calls to manipulate
.Tn POSIX
message 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.
.Pp
The most common usage is as follows:
.Pp
.Dl "mount -t mqueuefs null /mnt/mqueue"
.Pp
where
.Pa /mnt/mqueue
is a mount point.
.Pp
It is possible to define an entry in
.Pa /etc/fstab
that looks similar to:
.Bd -literal
null /mnt/mqueue mqueuefs rw 0 0
.Ed
.Pp
This will mount
.Nm
at the
.Pa /mnt/mqueue
mount point during system boot.
Using
.Pa /mnt/mqueue
as a permanent mount point is not advised as its intention
has always been to be a temporary mount point.
See
.Xr hier 7
for more information on
.Fx
directory layout.
.Pp
Some common tools can be used on the file system, e.g.:
.Xr cat 1 ,
.Xr chmod 1 ,
.Xr chown 8 ,
.Xr ls 1 ,
.Xr 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,
.Dq Li "touch /mnt/mqueue/myqueue" ,
will create a message queue named
.Pa 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
.Xr mq_open 2
system call to create a queue as it
allows the user to specify different attributes.
.Pp
To see the queue's attributes, just read the file:
.Pp
.Dl "cat /mnt/mqueue/myqueue"
.Sh SEE ALSO
.Xr mq_open 2 ,
.Xr nmount 2 ,
.Xr unmount 2 ,
.Xr mount 8 ,
.Xr umount 8
.Sh AUTHORS
This manual page was written by
.An David Xu Aq Mt davidxu@FreeBSD.org .
|
