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/share/man/man5/mqueuefs.5

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  1.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org>
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 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 .