nbddump(1)

💅 nbddump — hexdump the content of a disk over NBD ✨

okay so bestie, welcome to nbddump(1) from the LIBNBD squad 🫶 this is the part of the libnbd family that lets you literally look at a disk over NBD. like, peek inside. with your eyeballs. iconic behaviour fr fr 💖

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✨ SYNOPSIS ✨

 nbddump [-n N|--length N] [-o N|--offset N] NBD

"NBD" is an NBD URI or a subprocess, and yes those are your two flavours 🍓:

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

also, the two little help-me-out modes:

 nbddump --help

 nbddump --version

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🌸 DESCRIPTION 🌸

nbddump prints the content of a disk from an NBD server using the usual hexdump format, and ngl the output is so satisfying to look at 😭💜:

 $ 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 🎀

okay so let's break down the ~anatomy~ of a line, because it's giving three fields and each one is doing its own thing:

• the first field (everything before the ":") is the offset within the file, in hexadecimal. that's your "where am I" ✨
• the second field shows the hex codes of bytes read from the file. the raw material 💅
• the third field shows the ASCII equivalent characters — but only if printable 👑

and then there's the splat character "☆" — a literal little star 😭⭐ — which means lines of repeated output have been squashed. and listen, bestie, this is not just for lines of zero bytes: it's any case where the next line shown would be the same as the previous line. so don't come for me saying "why is there a star on my non-zero data" because that's the whole point 🫶

🦋 Subprocess 🦋

nbddump can also run an NBD server as a subprocess, which is highkey the coolest feature ngl 🔥. this requires an NBD server which understands systemd socket activation — like 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) — yes, an empty floppy, main character energy 💾✨:

 $ mkdir /var/tmp/empty
 $ nbddump -- [ nbdkit floppy /var/tmp/empty ]
 0000: 00 00 00 4d 53 57 49 4e 34 2e 31 00 00 00 00 00 |...MSWIN4.1.....|
 0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
 ☆
 01b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fe |................|
 01c0: ff ff 0c fe ff ff 00 08 00 00 80 00 00 00 00 00 |................|

to dump out some test data using nbdkit-data-plugin(1):

 $ nbddump -- [ nbdkit data ' @0x1000 "hello!" ' ]
 0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │················│
 ☆
 1000: 68 65 6c 6c 6f 21                               │hello!          │

⚠️ okay important bestie note: "[ ... ]" are separate parameters, and they must be surrounded by spaces. and "--" separates nbddump parameters from subprocess parameters. do not skip the spaces, i am begging 🙈

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💅 OPTIONS 💅

• --help — display brief command line help and exit. your little "what do i do" button 🎀
• --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. (and yes, they accept both spellings, we're inclusive here 🫶🌈)
• --length=N, --limit=N, -n N — dump up to N bytes and then stop. so you can be like "okay i've seen enough" 💀
• --offset=N, --skip=N, -o N — start the dump at offset N bytes. skip to the good part 🎵
• -V, --version — display the package name and version and exit. the classic 👑

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🌈 SEE ALSO 🌈

go check out the whole fam, they're all iconic 💜:

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

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👑 AUTHORS 👑

Richard W.M. Jones — the legend themselves 🫡💖

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🎀 COPYRIGHT 🎀

Copyright Red Hat

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⭐ LICENSE ⭐

okay so legal bit, but make it cute:

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. (like, fr fr, no promises 😭)

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

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and that's the page, bestie!! 🦋 this little gem is libnbd-1.25.8, dated 2026-10-13 — go hexdump something and slay 💅✨🍓