#!/bin/sh

str_without_white_in_between=''

for item in `cat`; do # note: all those white in between will be treated as separator
 str_without_white_in_between=${str_without_white_in_between}${item}
done

printf "%s\n" "$str_without_white_in_between" | hexdump -b -c

## another way
#	read dummy oct << EOF
#	$(dd bs=1 count=1|od -b)
#	EOF

od – octal, decimal, hex, ASCII dump
     -a             Output named characters.
     -b             Output octal bytes.
     -c             Output C-style escaped characters.
     -d             Output unsigned decimal shorts.  Equivalent to -t u2.