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

Yet another solution, using head, tail and printf:

for a in $( seq $( cat file.txt | wc -c ) ) ; do cat file.txt | head -c$a | tail -c1 | xargs -0 -I{} printf '%s %0X\n' {} "'{}" ; done

More readable:

#!/bin/bash

function usage() {
    echo "Need file with size > 0"
    exit 1
}

test -s "$1" || usage

for a in $( seq $( cat $1 | wc -c ) )
do
    cat $1 | head -c$a | tail -c1 | \
    xargs -0 -I{} printf '%c %#02x\n' {} "'{}"
done