NAME

       nbdkit-streaming-plugin - nbdkit streaming plugin

SYNOPSIS

        nbdkit streaming pipe=FILENAME [size=SIZE]

DESCRIPTION

       "nbdkit-streaming-plugin" is a plugin for nbdkit(1) that can turn certain kinds of input
       into a stream.

       If the NBD client opens the NBD port, and writes from the start to the end of the disk
       without seeking backwards, then this plugin will turn the resulting disk image into a
       stream of data which is written to the named "pipe" parameter.

                      ┌───────────┐
        client        │ nbdkit    │        plugin streams
        writes ──────▶│ streaming │──────▶ data to pipe
                      │ plugin    │
                      └───────────┘

       Typical usage is with qemu tools.  The following command will not work because the output
       is a pipe or socket:

        qemu-img convert input -O raw pipe

       However this will work:

        nbdkit -U - streaming pipe=pipe --run '
          qemu-img convert -n input -O raw $nbd
        '

                     ┌───────────┐       ┌───────────┐
        reads        │ qemu-img  │       │ nbdkit    │        plugin streams
        input ──────▶│ convert   │──────▶│ streaming │──────▶ data to pipe
        file         │ command   │       │ plugin    │
                     └───────────┘      ↑└───────────┘
                                     Unix domain socket (-U -)

       For use of the --run and -U - options, see nbdkit-captive(1).

PARAMETERS

       pipe=FILENAME
           Write to the named pipe or socket.  If the pipe or socket does not exist, then it is
           created (as a named FIFO), otherwise the existing pipe or socket is opened and used.

           This parameter is required.

       size=SIZE
           Specify the virtual size of the stream.

           This parameter is optional.  If not specified, then the virtual disk appears to the
           client to be very large (effectively infinite).  Whether you need to specify this
           parameter depends on the client.  Some clients don't check the size and just
           write/stream, others do checks or calculations based on the apparent size.

FILES

       $plugindir/nbdkit-streaming-plugin.so
           The plugin.

           Use "nbdkit --dump-config" to find the location of $plugindir.

VERSION

       "nbdkit-streaming-plugin" first appeared in nbdkit 1.2.

SEE ALSO

       nbdkit(1), nbdkit-plugin(3).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2014 Red Hat Inc.

LICENSE

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       permitted provided that the following conditions are met:

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           conditions and the following disclaimer.

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           conditions and the following disclaimer in the documentation and/or other materials
           provided with the distribution.

       ·   Neither the name of Red Hat nor the names of its contributors may be used to endorse
           or promote products derived from this software without specific prior written
           permission.

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