DOKK / manpages / debian 10 / nbdkit-plugin-perl / nbdkit-tar-plugin.1.en
nbdkit-tar-plugin(1) NBDKIT nbdkit-tar-plugin(1)

nbdkit-tar-plugin - read and write files inside tar files without unpacking

 nbdkit tar tar=FILENAME.tar file=PATH_INSIDE_TAR

 nbdkit tar tar=file.tar file=some/disk.img
 guestfish --format=raw -a nbd://localhost

The popular "Open Virtual Appliance" (OVA) format is really an uncompressed tar file containing (usually) VMDK-format files, so you could access one file in an OVA like this:

 $ tar tf rhel.ova
 rhel.ovf
 rhel-disk1.vmdk
 rhel.mf
 $ nbdkit -r tar tar=rhel.ova file=rhel-disk1.vmdk
 $ guestfish --ro --format=vmdk -a nbd://localhost

"nbdkit-tar-plugin" is a plugin which can read and writes files inside an uncompressed tar file without unpacking the tar file.

The "tar" and "file" parameters are required, specifying the name of the uncompressed tar file and the exact path of the file within the tar file to access as a disk image.

This plugin will not work on compressed tar files.

Use the nbdkit -r flag to open the file readonly. This is the safest option because it guarantees that the tar file will not be modified. Without -r writes will modify the tar file.

Also writing to the tar file does not change data checksums stored in other files (the "rhel.mf" file in the example above), and as these will become incorrect you probably won't be able to open the file with another tool afterwards.

The disk image cannot be resized.

https://github.com/libguestfs/nbdkit/blob/master/plugins/tar/tar.pl, nbdkit(1), nbdkit-plugin(3), nbdkit-perl-plugin(3).

Richard W.M. Jones.

Based on the virt-v2v OVA importer written by Tomáš Golembiovský.

Copyright (C) 2017 Red Hat Inc.

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2019-01-26 nbdkit-1.10.3