Basic PoW with deterministic output

pow.bash

#!/usr/bin/env bash

# Brief: Basic Proof-of-Work (PoW) with deterministic output for input string passed as parameter.
# Usage: ./pow <text>
# Ctrl+'\' (SIGQUIT) to check current nonce anytime
# Output: Nonce and 00* SHA256-Hash
#===================================================

hash_of(){
  sha256sum <(echo "${1}") | awk '{print $1}'
}; export -f hash_of

trap 'echo Nonce: "${nonce}"' exit QUIT

input="${1}"
input_hash="$(hash_of "${input}")"

nonce=0

until [[ "${final_hash}" == 00* ]];do
  nonce_hash="$(hash_of "${nonce}")"
  final_hash="$(hash_of "${input_hash}_${nonce_hash}")"
  ((nonce++))
done
echo "Hash: ${final_hash}"