Bash functions for converting hexadecimal strings back to ASCII and for converting ASCII strings to hexadecimal strings.

str_hex_conversion.func.sh

#!/bin/bash
#
hextostr() {
	local i _hs="$*"
	local _hsl="${#_hs}"
	printf '%s\n' "$(for ((i=0; i < _hsl; i+=2)); do echo -ne "\x${_hs:i:2}"; done)"
	unset -v _hsl _hs i
}

#hextostr '48656C6C6F20776F726C6421'
#Hello world!

strtohex() {
	local i _as="$*"
	local _asl="${#_as}"
	for ((i=0; i < _asl; i++))
	do
		printf '%02x' "'${_as:i:1}"
	done
	echo
	unset -v _asl _as i
}

#strtohex 'Hello world!'
#48656c6c6f20776f726c6421