mq_open Hanging

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LEARN ABOUT FREEBSD

mqueuefs

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

Programming