NAME

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

SYNOPSIS

        nbdkit tar [tar=]FILENAME.tar file=PATH_INSIDE_TAR

DEPRECATED

       The tar plugin is deprecated in nbdkit ≥ 1.22 and will be removed in nbdkit 1.26.  It has been replaced
       with a filter with the same functionality, see nbdkit-tar-filter(1).  You can use the filter like this:

        nbdkit file FILENAME.tar --filter=tar tar-entry=PATH_INSIDE_TAR

EXAMPLES

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

   Opening a disk image inside an OVA file
       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 rhel.ova file=rhel-disk1.vmdk
        $ guestfish --ro --format=vmdk -a nbd://localhost

       In this case the tarball is opened readonly (-r option).  The plugin supports write access, but writing
       to the VMDK file in the tarball does not change data checksums stored in other files (the "rhel.mf" file
       in this example), and as these will become incorrect you probably won't be able to open the file with
       another tool afterwards.

DESCRIPTION

       "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.

       The disk image cannot be resized.

PARAMETERS

       [tar=]FILENAME.tar
           The path of the tarball.  This parameter is required.

           "tar=" is a magic config key and may be omitted in most cases.  See "Magic parameters" in nbdkit(1).

       file=PATH_INSIDE_TAR
           The path of the file inside the tarball to serve.  This parameter is required.  It must exactly match
           the name stored in the tarball, so use "tar tf filename.tar"

NOTE

   Alternatives to the tar plugin
       The  tar  plugin ought to be a filter so that you can extract files from within tarballs hosted elsewhere
       (eg. using nbdkit-curl-plugin(1)).  However this is hard to implement  given  the  way  that  the  tar(1)
       command works.

       Nevertheless  you  can  apply  the  same technique even to tarballs hosted remotely, provided you can run
       tar(1) on them first.  The trick is to use the "tar -tRvf" options to find the block number of  the  file
       of  interest.   In  tar  files,  blocks are 512 bytes in size, and there is one hidden block used for the
       header, so you have to take the block number, add 1, and multiply by 512.

       For example:

        $ tar -tRvf disk.tar
        block 2: -rw-r--r-- rjones/rjones 105923072 2020-03-28 20:34 disk
        └──┬──┘                           └───┬───┘
        offset = (2+1)*512 = 1536           range

       You can then apply the offset filter:

        nbdkit --filter=offset \
                 curl https://example.com/disk.tar \
                      offset=1536 range=105923072

       If the remote file is compressed then add nbdkit-xz-filter(1):

        nbdkit --filter=offset --filter=xz \
                 curl https://example.com/disk.tar.xz \
                      offset=1536 range=105923072

VERSION

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

SEE ALSO

       nbdkit(1), nbdkit-offset-filter(1), nbdkit-plugin(3), nbdkit-tar-filter(1), nbdkit-xz-filter(1), tar(1).

AUTHORS

       Richard W.M. Jones.

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

COPYRIGHT

       Copyright (C) 2017-2020 Red Hat Inc.

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.

nbdkit-1.24.1                                      2021-01-20                               nbdkit-tar-plugin(1)