1nbdkit-offset-filter(1)             NBDKIT             nbdkit-offset-filter(1)
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NAME

6       nbdkit-offset-filter - nbdkit offset filter
7

SYNOPSIS

9        nbdkit --filter=offset plugin offset=OFFSET range=LENGTH [plugin-args...]
10

DESCRIPTION

12       "nbdkit-offset-filter" is a filter that limits requests to the byte
13       range "[offset .. offset+range-1]" within another plugin.
14

PARAMETERS

16       offset=OFFSET
17           The start offset.  The offset must be ≥ 0.
18
19           This parameter is optional.  If not given then "offset=0" is
20           assumed.
21
22       range=LENGTH
23           The length of data to serve.
24
25           This parameter is optional.  If not given then the range is served
26           starting from the offset through to the end of the underlying
27           file/device.
28
29       Note it is an error if the offset and/or range specify data which lies
30       beyond the end of the underlying device.  Use nbdkit-truncate-filter(1)
31       to truncate or extend the size of plugins.
32

EXAMPLES

34   Serve part of a file
35       Using nbdkit-file-plugin(1), serve the file "disk.img" starting at
36       offset "1M".  The total length served is "100M" (the underlying file
37       must therefore be at least "101M" in length):
38
39        nbdkit --filter=offset file disk.img offset=1M range=100M
40
41   Serve a single partition
42       An easier way to do this is with nbdkit-partition-filter(1).
43
44       One way to serve a single partition from a disk is to find the start
45       and length of the partition, eg using:
46
47        $ parted disk.img -- unit b print
48        ...
49        Number  Start   End         Size        Type     File system  Flags
50         1      65536B  104792575B  104727040B  primary  ext2
51
52       You can then serve the partition only using:
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54        nbdkit --filter=offset file disk.img offset=65536 range=104727040
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FILES

57       $filterdir/nbdkit-offset-filter.so
58           The filter.
59
60           Use "nbdkit --dump-config" to find the location of $filterdir.
61

VERSION

63       "nbdkit-offset-filter" first appeared in nbdkit 1.2.
64

SEE ALSO

66       nbdkit(1), nbdkit-file-plugin(1), nbdkit-filter(3),
67       nbdkit-partition-filter(1), nbdkit-tar-filter(1),
68       nbdkit-truncate-filter(1).
69

AUTHORS

71       Eric Blake
72
73       Richard W.M. Jones
74

76       Copyright (C) 2018 Red Hat Inc.
77

LICENSE

79       Redistribution and use in source and binary forms, with or without
80       modification, are permitted provided that the following conditions are
81       met:
82
83       •   Redistributions of source code must retain the above copyright
84           notice, this list of conditions and the following disclaimer.
85
86       •   Redistributions in binary form must reproduce the above copyright
87           notice, this list of conditions and the following disclaimer in the
88           documentation and/or other materials provided with the
89           distribution.
90
91       •   Neither the name of Red Hat nor the names of its contributors may
92           be used to endorse or promote products derived from this software
93           without specific prior written permission.
94
95       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
96       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
97       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
98       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
99       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
100       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
101       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
102       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
103       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
104       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
105       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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109nbdkit-1.25.8                     2021-05-25           nbdkit-offset-filter(1)
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