linux shell scripting: hex string to bytes

Question

Lets say that I have a string "5a". This is the hex representation of the ASCII letter 'Z'. I need to know a linux shell command which will take a hex string and output the binary bytes the string represents.

So if I do echo "5a" | command_im_looking_for > temp.txt

can I open temp.txt, I will see a solitary letter Z.

Answer 1

echo -n 5a | perl -pe 's/([0-9a-f]{2})/chr hex $1/gie'

Note that this won't skip non-hex characters. If you want just the hex (no whitespace from the original string etc):

echo 5a | perl -ne 's/([0-9a-f]{2})/print chr hex $1/gie'

Also, zsh and bash support this natively in echo:

echo -e '\x5a'

Answer 2

echo 5a | python -c "import sys; print chr(int(sys.stdin.read(),base=16))"

Answer 3

od -c or hexdump -c

Answer 4

depending on where you got that "5a', you can just append \x to it and pass to printf

$ a=5a
$ a="\x${a}"
$ printf "$a"
Z