125 lines
3.5 KiB
Groff
125 lines
3.5 KiB
Groff
.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 30, 2005
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.Dt MQUEUEFS 5
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.Os
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.Sh NAME
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.Nm mqueuefs
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.Nd POSIX message queue file system
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.Sh SYNOPSIS
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To link into kernel:
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.Pp
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.D1 Cd "options P1003_1B_MQUEUE"
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.Pp
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To load as a kernel loadable module:
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.Pp
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.Dl "kldload mqueuefs"
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.Sh DESCRIPTION
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The
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.Nm
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module will permit the
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.Fx
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kernel to support
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.Tn POSIX
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message queue.
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The module contains system calls to manipulate
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.Tn POSIX
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message queues.
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It also contains a file system to implement a view for all message queues of
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the system.
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This helps users to keep track of their message queues and make
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it more easily usable without having to invent additional tools.
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.Pp
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The most common usage is as follows:
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.Pp
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.Dl "mount -t mqueuefs null /mnt/mqueue"
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.Pp
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where
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.Pa /mnt/mqueue
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is a mount point.
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.Pp
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It is possible to define an entry in
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.Pa /etc/fstab
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that looks similar to:
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.Bd -literal
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null /mnt/mqueue mqueuefs rw 0 0
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.Ed
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.Pp
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This will mount
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.Nm
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at the
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.Pa /mnt/mqueue
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mount point during system boot.
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Using
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.Pa /mnt/mqueue
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as a permanent mount point is not advised as its intention
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has always been to be a temporary mount point.
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See
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.Xr hier 7
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for more information on
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.Fx
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directory layout.
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.Pp
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Some common tools can be used on the file system, e.g.:
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.Xr cat 1 ,
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.Xr chmod 1 ,
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.Xr chown 8 ,
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.Xr ls 1 ,
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.Xr rm 1 ,
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etc.
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To use only the message queue system calls, it is not necessary for
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user to mount the file system, just load the module or compile it
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into the kernel.
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Manually creating a file, for example,
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.Dq Li "touch /mnt/mqueue/myqueue" ,
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will create a message queue named
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.Pa myqueue
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in the kernel, default
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message queue attributes will be applied to the queue.
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It is not
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advised to use this method to create a queue;
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it is better to use the
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.Xr mq_open 2
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system call to create a queue as it
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allows the user to specify different attributes.
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.Pp
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To see the queue's attributes, just read the file:
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.Pp
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.Dl "cat /mnt/mqueue/myqueue"
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.Sh SEE ALSO
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.Xr nmount 2 ,
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.Xr mq_open 2 ,
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.Xr unmount 2 ,
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.Xr mount 8 ,
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.Xr umount 8
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.Sh AUTHORS
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This manual page was written by
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.An "David Xu" Aq davidxu@FreeBSD.org .
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