Merkle root of a bitcoin block calculated in bash

merkle.sh

#!/bin/bash

# usage : ./merkel.sh tx1 tx2 ... txn

# better: ./merkel.sh $(bitcoin-cli getblock {hashOfABlock}|jq -rc '.tx[]')

function concat() {
  echo -e "$1$2"
}

function toggleEndian() {
  echo $(echo $1 |tac -rs ..)
}

function hash() {
  echo $(echo $1|xxd -r -p|sha256sum| tr -d "\n *-"|xxd -r -p|sha256sum| tr -d "\n *-")
}

function merkleTree() {
  nbArgs=$#
  current=()
  if [ $nbArgs -eq 1 ];
  then
    echo $1
  else
    if [ $nbArgs -eq 2 ];
    then
      echo $(hash $(concat $1 $2))
    else
      i=0
      for leaf in $@
      do
        isOdd=$(expr $nbArgs % 2)
        modulo=$(expr $i % 2)
        if [ $modulo -eq 0 ];
        then
          prev=$leaf
          if [ $isOdd -eq 1 ];
          then
            if [ $((i+1)) -eq $# ];
            then
              current+=($(merkleTree $leaf $leaf))
            fi
          fi
        else
          current+=($(merkleTree $prev $leaf))
        fi
        i=$((i+1))
      done
      echo $(merkleTree "${current[@]}")
    fi
  fi
}

function merkleTreeInit() {
  params=()
  for param in $@
  do
    params+=($(toggleEndian $param))
  done
  echo $(toggleEndian $(merkleTree "${params[@]}"))
}

merkleTreeInit $@