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1.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in 13.\" the documentation and/or other materials provided with the 14.\" distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd November 30, 2005 31.Dt MQUEUEFS 5 32.Os 33.Sh NAME 34.Nm mqueuefs 35.Nd POSIX message queue file system 36.Sh SYNOPSIS 37To link into kernel: 38.Pp 39.Cd "options P1003_1B_MQUEUE" 40.Pp 41To load as a kernel loadable module: 42.Pp 43.Dl "kldload mqueuefs" 44.Sh DESCRIPTION 45The 46.Nm 47module will permit the 48.Fx 49kernel to support 50.Tn POSIX 51message queue. 52The module contains system calls to manipulate 53.Tn POSIX 54message queues. 55It also contains a file system to implement a view for all message queues of 56the system. 57This helps users to keep track of their message queues and make 58it more easily usable without having to invent additional tools. 59.Pp 60The most common usage is as follows: 61.Pp 62.Dl "mount -t mqueuefs null /mnt/mqueue" 63.Pp 64where 65.Pa /mnt/mqueue 66is a mount point. 67.Pp 68It is possible to define an entry in 69.Pa /etc/fstab 70that looks similar to: 71.Bd -literal 72null /mnt/mqueue mqueuefs rw 0 0 73.Ed 74.Pp 75This will mount 76.Nm 77at the 78.Pa /mnt/mqueue 79mount point during system boot. 80Using 81.Pa /mnt/mqueue 82as a permanent mount point is not advised as its intention 83has always been to be a temporary mount point. 84See 85.Xr hier 7 86for more information on 87.Fx 88directory layout. 89.Pp 90Some common tools can be used on the file system, e.g.: 91.Xr cat 1 , 92.Xr chmod 1 , 93.Xr chown 8 , 94.Xr ls 1 , 95.Xr rm 1 , 96etc. 97To use only the message queue system calls, it is not necessary for 98user to mount the file system, just load the module or compile it 99into the kernel. 100Manually creating a file, for example, 101.Dq Li "touch /mnt/mqueue/myqueue" , 102will create a message queue named 103.Pa myqueue 104in the kernel, default 105message queue attributes will be applied to the queue. 106It is not 107advised to use this method to create a queue; 108it is better to use the 109.Xr mq_open 2 110system call to create a queue as it 111allows the user to specify different attributes. 112.Pp 113To see the queue's attributes, just read the file: 114.Pp 115.Dl "cat /mnt/mqueue/myqueue" 116.Sh SEE ALSO 117.Xr mq_open 2 , 118.Xr nmount 2 , 119.Xr unmount 2 , 120.Xr mount 8 , 121.Xr umount 8 122.Sh AUTHORS 123This manual page was written by 124.An "David Xu" Aq davidxu@FreeBSD.org .