var="ASCII"
echo "${var} has the length ${#var}, and is $(printf "%s" "$var"| wc -c) bytes long"

Müller has the length 6, and is 7 bytes long

var='🧜🏿‍♀️'
echo "${var} has the length ${#var}, and is $(printf "%s" "$var"| wc -c) bytes long"

🧜🏿‍♀️ has the length 5, and is 17 bytes long

var="e\xcc\x81"
echo "${var} has the length ${#var}, and is $(printf "%s" "$var"| wc -c) bytes long"

é has the length 9, and is 9 bytes long

> printf "e\xcc\x81"|wc -c
3
> printf "%s" "${var}" |wc -c
9
> echo -n ${var} |wc -c
3
> echo "${var} has the length ${#var}, and is $(printf "%s" "$var"| wc -c) bytes long"
é has the length 9, and is 9 bytes long
> printf "%s" "${var}" |xxd
00000000: 655c 7863 635c 7838 31                   e\xcc\x81

#!/bin/bash
echo -n 'hello'
sleep infinity

take 5 ./generate-infinite-byte-stream
# gives 'hello' and returns with exit code 0

./generate-infinite-byte-stream | head -c 5
# this returns 'hello', but never terminates

#!/bin/bash

# infile is just a temporary test file for now, which will be replaced with /dev/sdb, for instance
infile=test.txt
offset=0

while true; do
  byte=dd status='none' bs=1 count=1 if="$infile" skip=$offset
  ret=$?

  # the following doesn't appear to work
  # ret is always 0, even when the end of file/device is reached
  # how do I correctly determine if dd has reached the end of file/device?
  if [ $ret -gt 0 ]; then
    echo 'error, or end of file reached'
    break
  fi

  # I don't know how to correctly determine if the byte is non-zero
  # how do I determine if the read byte is non-zero?
  if [ $byte ???? ]; then
    echo "non-zero byte found at $offset"
    break
  fi

  ((++offset))
done