Greetings, I have used xxd along with the same parameters to pipe binary characters to a binary file. The reason you are seeing ascii characters is because all the command with those parameters displays the result in ascii and all of your characters from the binary conversion result in regular ascii characters. I found this from a quick search to confirm: https://www.scadacore.com/tools/programming-calculators/online-hex-converter/ If you try this one from terminal you will see it outputs special characters because it cannot display them from a terminal. echo 0ee221ef9e00dfa69efb3b1112bfbb2f | xxd -r -p The sample I listed is part of this script (I'm the author) and used with file encryption. Basically it converts hex to binary and appends the binary bytes to a binary file. Near the bottom of the document I list step by step example of encryption and how to use the commands. For this script xxd is critical because it's the only way to convert to and from hex from shell without installing additional tools. https://fastsitephp.com/en/documents/file-encryption-bash # Append IV to the end of the file. # Typically in secure applications and sites the IV is saved with the # encrypted data while only the key is required to be secret. echo 0ee221ef9e00dfa69efb3b1112bfbb2f | xxd -r -p >> crypto_test_10mb.enc # Now view the end of the file after adding IV tail -c 32 crypto_test_10mb.enc | hexdump -C -v More on reddit.com

/usr/bin/xxd is part of macOS (up to and including 12.6). Current version: xxd 2022-01-14 by Juergen Weigert et al.. Not necessary to install anything, really. And not simple to delete as well. Have you checked your /usr/bin? Have you checked your PATH environment? What does command -v xxd say? What happens when you execute /usr/bin/xxd? More on reddit.com

One is little-endian and the other is big-endian. Check their respective man pages. I'm sure there's a switch to switch endedness. More on reddit.com

What is those extra 0000 0000 at the start You've asked for the leading address to be decoded as data using -p how can I do xxd -r -p without those? You can do it like this: cut -d: -f 2 < input.txt | xxd -r -p > output.tar.gz (You can also just drop the -p, but Reddit really hates on the stackoverflow type answers where they say "don't do that, do this instead") More on reddit.com