Read a file by bytes in BASH

Question

I need to read first byte of file I specified, then second byte,third and so on. How could I do it on BASH? P.S I need to get HEX of this bytes

Answer 1

I have a suggestion to give, but would like a feedback from everybody and manly a personal advice from syntaxerror's user.

I don't know much about bash but I thought maybe it would be better to have "cat $1" stored in a variable.. but the problem is that echo command will also bring a small overhead right?

test -s "$1" || (echo "Need a file with size greater than 0!"; exit 1)
a=0
rfile=$(cat $1)
max=$(echo $rfile | wc -c)
while [[ $((++a)) -lt $max ]]; do
  echo $rfile | head -c$a | tail -c1 | \
  xargs -0 -I{} printf '%c %#02x\n' {} "'{}"
done

in my opinion it would have a better performance but i haven't perf'tested..