1nbdkit-streaming-plugin(1) NBDKIT nbdkit-streaming-plugin(1)
2
6 nbdkit-streaming-plugin - nbdkit streaming plugin
7
9 nbdkit streaming pipe=FILENAME [size=SIZE]
10
12 "nbdkit-streaming-plugin" is a plugin for nbdkit(1) that can turn
13 certain kinds of input into a stream.
14 If the NBD client opens the NBD port, and writes from the start to the
16 end of the disk without seeking backwards, then this plugin will turn
17 the resulting disk image into a stream of data which is written to the
18 named "pipe" parameter.
19 ┌───────────┐
21 client │ nbdkit │ plugin streams
22 writes ──────▶│ streaming │──────▶ data to pipe
23 │ plugin │
24 └───────────┘
25 Typical usage is with qemu tools. The following command will not work
27 because the output is a pipe or socket:
28 qemu-img convert input -O raw pipe
30 However this will work:
32 nbdkit -U - streaming pipe=pipe --run '
34 qemu-img convert -n input -O raw $nbd
35 '
36 ┌───────────┐ ┌───────────┐
38 reads │ qemu-img │ │ nbdkit │ plugin streams
39 input ──────▶│ convert │──────▶│ streaming │──────▶ data to pipe
40 file │ command │ │ plugin │
41 └───────────┘ ↑└───────────┘
42 Unix domain socket (-U -)
43 For use of the --run and -U - options, see nbdkit-captive(1).
45
47 pipe=FILENAME
48 Write to the named pipe or socket. If the pipe or socket does not
49 exist, then it is created (as a named FIFO), otherwise the existing
50 pipe or socket is opened and used.
51 This parameter is required.
53 size=SIZE
55 Specify the virtual size of the stream.
56 This parameter is optional. If not specified, then the virtual
58 disk appears to the client to be very large (effectively infinite).
59 Whether you need to specify this parameter depends on the client.
60 Some clients don't check the size and just write/stream, others do
61 checks or calculations based on the apparent size.
62
64 nbdkit(1), nbdkit-plugin(3).
65
67 Richard W.M. Jones
68
70 Copyright (C) 2014 Red Hat Inc.
71
73 Redistribution and use in source and binary forms, with or without
74 modification, are permitted provided that the following conditions are
75 met:
76 · Redistributions of source code must retain the above copyright
78 notice, this list of conditions and the following disclaimer.
79 · Redistributions in binary form must reproduce the above copyright
81 notice, this list of conditions and the following disclaimer in the
82 documentation and/or other materials provided with the
83 distribution.
84 · Neither the name of Red Hat nor the names of its contributors may
86 be used to endorse or promote products derived from this software
87 without specific prior written permission.
88 THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
90 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
91 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
92 PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
93 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
94 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
95 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
96 BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
97 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
98 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
99 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
100nbdkit-1.12.3 2019-05-22 nbdkit-streaming-plugin(1)