hanoiScript.sh

#!/bin/bash

# USAGE
# hanoiScript.sh [n] [from] [to] [by]

if [[ -z $1 ]] ; then
  echo "error: No arguments were passed"
  exit 1
fi

# hanoi() 
# It Recursive function to ring from first pole to another pole
# with the help of a third pole
# called (n^2 - 1) times
hanoi()
{
  local rings="$1"
  local fromPole="$2"
  local toPole="$3"
  local viaPole="$4"
  
  if [[ "$rings" > "1" ]] ; then
    hanoi $(($rings - 1)) $fromPole $viaPole $toPole
    hanoi 1 $fromPole $toPole $viaPole
    hanoi $(($rings - 1)) $viaPole $toPole $fromPole
  else
    echo "Moving ring from pole $fromPole to pole $toPole"
  fi
}

# arguments
from=${2:-1}
to=${3:-2}
by=${4:-3}
hanoi $1 $from $to $by