nbdkit-offset-filter - Man Page
nbdkit offset filter
Synopsis
nbdkit --filter=offset plugin offset=OFFSET range=LENGTH [plugin-args...]
Description
nbdkit-offset-filter is a filter that limits requests to the byte range [offset .. offset+range-1] within another plugin.
Parameters
- offset=OFFSET
The start offset. The offset must be ≥ 0.
This parameter is optional. If not given then
offset=0is assumed.- range=LENGTH
The length of data to serve.
This parameter is optional. If not given then the range is served starting from the offset through to the end of the underlying file/device.
Note it is an error if the offset and/or range specify data which lies beyond the end of the underlying device. Use nbdkit-truncate-filter(1) to truncate or extend the size of plugins.
Examples
Serve part of a file
Using nbdkit-file-plugin(1), serve the file disk.img starting at offset 1M. The total length served is 100M (the underlying file must therefore be at least 101M in length):
nbdkit --filter=offset file disk.img offset=1M range=100M
Serve a single partition
An easier way to do this is with nbdkit-partition-filter(1).
One way to serve a single partition from a disk is to find the start and length of the partition, eg using:
$ parted disk.img -- unit b print ... Number Start End Size Type File system Flags 1 65536B 104792575B 104727040B primary ext2
You can then serve the partition only using:
nbdkit --filter=offset file disk.img offset=65536 range=104727040
Files
- $filterdir/nbdkit-offset-filter.so
The filter.
Use
nbdkit --dump-configto find the location of$filterdir.
Version
nbdkit-offset-filter first appeared in nbdkit 1.2.
See Also
nbdkit(1), nbdkit-file-plugin(1), nbdkit-filter(3), nbdkit-partition-filter(1), nbdkit-protect-filter(1), nbdkit-tar-filter(1), nbdkit-truncate-filter(1).
Authors
Eric Blake
Richard W.M. Jones
Copyright
Copyright Red Hat
License
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
- Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of 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.
THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Referenced By
nbdkit(1), nbdkit-filter(3), nbdkit-partition-filter(1), nbdkit-pattern-plugin(1), nbdkit-protect-filter(1), nbdkit-tar-filter(1), nbdkit-truncate-filter(1).