Farley Flud wrote this post while blinking in Morse code:

I need to replace some bytes in potentially very large binary files.

Fortunately, I know the offset and I know the byte length.

I can easily invoke a hex editor and manually do the replacement
but I desire a faster method using CLI.

How can I do this with CLI?

This link has some ideas:

https://stackoverflow.com/questions/4783657/write-byte-at-address-hexedit-modify-binary-from-the-command-line

I most crack open bvi these days. Previously I used hexer a lot. But they're no scriptable afaik.

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I need to replace some bytes in potentially very large binary files.

Fortunately, I know the offset and I know the byte length.

I can easily invoke a hex editor and manually do the replacement
but I desire a faster method using CLI.

How can I do this with CLI?



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Systemd: solving all the problems that you never knew you had.

--- SoupGate-Win32 v1.05
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On Sun, 4 May 2025 11:57:43 -0400, Chris Ahlstrom wrote:

This link has some ideas:

https://stackoverflow.com/questions/4783657/write-byte-at-address-hexedit-modify-binary-from-the-command-line

That does work on my files.

printf '\x49\x4e\x41\x52\x59' | dd of=$1 bs=1 seek=7 count=5 conv=notrunc

But the offset has to known beforehand and the replacement bytes
have to be entered manually. It's just as slow as using search and
replace with a hex editor.

Moreover, this method can only overwrite existing bytes and cannot insert
extra bytes at a given offset.

Incidentally, my fave hex editor is a java program called Hexditor:

http://flying.guy.chez-alice.fr/HexditorEn.php

Unlike all other GNU/Linux hex editors, Hexditor allows full insertion/ deletion anywhere in the file.

Another possibility is wxHexEditor:

https://www.wxhexeditor.org/home.php

But this software is still in beta for the past 8 years!

The author is correct though: "because there is no good hex editor for
Linux system."



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Systemd: solving all the problems that you never knew you had.

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On Sun, 04 May 2025 19:23:22 +0000, Farley Flud wrote:

On Sun, 4 May 2025 11:57:43 -0400, Chris Ahlstrom wrote:

This link has some ideas:

https://stackoverflow.com/questions/4783657/write-byte-at-address-hexedit-modify-binary-from-the-command-line

That does work on my files.

printf '\x49\x4e\x41\x52\x59' | dd of=$1 bs=1 seek=7 count=5 conv=notrunc

But the offset has to known beforehand and the replacement bytes
have to be entered manually. It's just as slow as using search and
replace with a hex editor.

For the record, I just discovered another program that is designed
to search/replace on binary files in the manner of sed:

https://sourceforge.net/projects/bbe-/

I am very surprised that there are not more such utilities.

Bbe seems to have a bit of a learning curve. For now, I'll stick
to manual editing with Hexditor.


--
Systemd: solving all the problems that you never knew you had.

--- SoupGate-Win32 v1.05
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On Sun, 04 May 2025 21:14:57 +0000, Farley Flud <ff@linux.rocks> wrote in <pan$883eb$94630766$6fffee5$582c1c40@linux.rocks>:

On Sun, 04 May 2025 19:23:22 +0000, Farley Flud wrote:

On Sun, 4 May 2025 11:57:43 -0400, Chris Ahlstrom wrote:

This link has some ideas:

https://stackoverflow.com/questions/4783657/write-byte-at-address- hexedit-modify-binary-from-the-command-line

That does work on my files.

printf '\x49\x4e\x41\x52\x59' | dd of=$1 bs=1 seek=7 count=5
conv=notrunc

But the offset has to known beforehand and the replacement bytes have
to be entered manually. It's just as slow as using search and replace
with a hex editor.

For the record, I just discovered another program that is designed to search/replace on binary files in the manner of sed:

https://sourceforge.net/projects/bbe-/

I am very surprised that there are not more such utilities.

Bbe seems to have a bit of a learning curve. For now, I'll stick to
manual editing with Hexditor.

Thank you for suggesting bbe.

Incidentally:

$ apt-cache show bbe
[...]
Section: universe/editors
Origin: Ubuntu
[...]
_ _ _ _ _ _ _

There are examples in the info documentation. For
viewing it, I recommend pinfo(1), which is sort of like
lynx(1) for info files.

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On 4 May 2025 21:39:49 GMT, vallor <vallor@cultnix.org> wrote in <m7q555FhujlU1@mid.individual.net>:

On Sun, 04 May 2025 21:14:57 +0000, Farley Flud <ff@linux.rocks> wrote
in <pan$883eb$94630766$6fffee5$582c1c40@linux.rocks>:

On Sun, 04 May 2025 19:23:22 +0000, Farley Flud wrote:

On Sun, 4 May 2025 11:57:43 -0400, Chris Ahlstrom wrote:

This link has some ideas:

https://stackoverflow.com/questions/4783657/write-byte-at-address-

hexedit-modify-binary-from-the-command-line

That does work on my files.

printf '\x49\x4e\x41\x52\x59' | dd of=$1 bs=1 seek=7 count=5
conv=notrunc

But the offset has to known beforehand and the replacement bytes have
to be entered manually. It's just as slow as using search and replace
with a hex editor.

For the record, I just discovered another program that is designed to
search/replace on binary files in the manner of sed:

https://sourceforge.net/projects/bbe-/

I am very surprised that there are not more such utilities.

Bbe seems to have a bit of a learning curve. For now, I'll stick to
manual editing with Hexditor.

Thank you for suggesting bbe.

Incidentally:

$ apt-cache show bbe [...]
Section: universe/editors Origin: Ubuntu [...]
_ _ _ _ _ _ _

There are examples in the info documentation. For viewing it, I
recommend pinfo(1), which is sort of like lynx(1) for info files

Ah, nevermind pinfo(1) -- it will fail an assertion:

pinfo: initializelinks.c:159: finddot: Assertion `closest>=str'
failed.
Aborted (core dumped)

...when you browse to Invocating bbe > Commands

--
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OS: Linux 6.14.5 Release: Mint 22.1 Mem: 258G
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On 4 May 2025 21:47:57 GMT, vallor wrote:

Ah, nevermind pinfo(1) -- it will fail an assertion:

pinfo: initializelinks.c:159: finddot: Assertion `closest>=str'
failed.
Aborted (core dumped)

...when you browse to Invocating bbe > Commands

I prefer tkinfo:

tkinfo /usr/share/info/bbe.info.bz2 &

File: bbe.info, Node: Commands, Next: Limits, Prev: Block, Up: Invoking bbe

3.3 `bbe' commands
==================

Commands in `bbe' can be divided in two groups: Block related commands
and byte related commands. Block related commands operate at block
level e.g. remove a block. Byte related commands work allways inside a
block and they don't have effect beyond the block boundaries.

Same escape codes for byte values in STRINGs can be used as in START
and STOP of block definition.
...





--
Systemd: solving all the problems that you never knew you had.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)