NAME

       nbddump - hexdump the content of a disk over NBD

SYNOPSIS

        nbddump NBD

       "NBD" is an NBD URI or subprocess:

        NBD := nbd://... | nbd+unix:// (or other URI formats)
             | [ CMD ARGS ... ]

        nbddump --help

        nbddump --version

DESCRIPTION

       nbddump prints the content of a disk from an NBD server using the usual hexdump format:

        $ nbddump nbd://localhost
        0000: 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │················│
        0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │················│
        ☆
        0100: 68 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21 00 00 00 │hello, world!···│
        0110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │················│
        ☆
        1000: 00 00 00 21                                     │···!            │

   Output format
       The first field (before the ":") is the offset within the file, in hexadecimal.

       The second field shows the hex codes of bytes read from the file.

       The third field shows the ASCII equivalent characters (if printable).

       A splat character ("☆") indicates lines of repeated output which have been squashed.
       (Note this is not just for lines of zero bytes, but any case where the next line shown
       would be the same as the previous line.)

   Subprocess
       nbddump can also run an NBD server as a subprocess.  This requires an NBD server which
       understands systemd socket activation, such as qemu-nbd(8) or nbdkit(1).

       For example, to dump out a qcow2 file as raw data:

        nbddump -- [ qemu-nbd -r -f qcow2 file.qcow2 ]

       To dump out an empty floppy disk created by nbdkit-floppy-plugin(1):

        mkdir /var/tmp/empty
        nbddump -- [ nbdkit floppy /var/tmp/empty ]

       Note that "[ ... ]" are separate parameters, and must be surrounded by spaces.  "--"
       separates nbddump parameters from subprocess parameters.

OPTIONS

       --help
           Display brief command line help and exit.

       --color
       --colour
       --no-color
       --no-colour
           Enable or disable ANSI colours in output.  By default we use colours if the output
           seems to be a terminal, and disable them if not.

       --length=N
       -n N
           Dump up to N bytes and then stop.

       -V
       --version
           Display the package name and version and exit.

SEE ALSO

       libnbd(3), nbdcopy(1), nbdfuse(1), nbdinfo(1), nbdsh(1), hexdump(1), file(1), qemu-img(1),
       nbdkit(1), qemu-nbd(8).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2022 Red Hat Inc.

LICENSE

       This library is free software; you can redistribute it and/or modify it under the terms of
       the GNU Lesser General Public License as published by the Free Software Foundation; either
       version 2 of the License, or (at your option) any later version.

       This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
       without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU Lesser General Public License for more details.

       You should have received a copy of the GNU Lesser General Public License along with this
       library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
       Floor, Boston, MA 02110-1301 USA