Mq serves a 9p file tree representing groups of buffered two-way data streams for multiple readers and writers accessible through the standard read(2) and write(2) file I/O interface.
Streams may be organized within an arbitrary file tree structure, which provides a means of namespacing and grouping.
<group>
<group>*
<stream>*
order
ctl
A directory denotes a group of streams. Any number of streams and sub-groups may be created within a group. Grouped streams share configuration and an order file.
The read-only meta-stream called order provides ordering information for
data written to streams within a group. Special readers such as
mq-cat(1) can tap into this stream to retrieve data coming from
multiple streams in the same order it was written.
See the mq(4) manual page for a complete
description of supported data modes, queue replay options, usage reference,
and other details.
Mount the mq(4) file server and use it to persist an rc(1) shell session.
mq -s detach
mount -c /srv/detach /n/detach
mkdir /n/detach/rc
cd /n/detach/rc
echo replay all >ctl
touch fd0 fd1 fd2
rc -i <fd0 >>fd1 >>[2]fd2 &
Attach to the shell:
cat fd1 & cat fd2 & cat >>fd0
The program pin(1) provides a polished interface for persisting
program sessions. It also makes use of the data ordering feature for
faithful reproduction of session history.
The program mq-cat(1) is an example of an ordered multi-stream reader.