basecvt

#!/bin/bash
# base conversion between: binary, octal, decimal, and hexadecimal
# usage: basecvt input_base output_base input_number
# created by zhouwei on 2020-10-01

set -e

if [[ $# != 3 ]]; then
	echo "Usage: basecvt input_base output_base input_number"
	echo "For example: basecvt 2 10 1111   # it will return 15"
	exit 1
fi

input_base=$1
output_base=$2
input_number=$3

input_number=$(echo "$input_number" | awk '{print(toupper($1))}')

if [[ $input_base -eq 2 ]]; then
    input_number=$(echo "$input_number" | sed -E 's/^0B//g')
elif [[ $input_base -eq 16 ]]; then
    input_number=$(echo "$input_number" | sed -E 's/^0X//g')
fi

# check the parameters, for example: 19 is a illegal input_number for input_base=8
echo "$((${input_base}#${input_number}))" >/dev/null
if [[ "$?" != 0 ]]; then
	echo "ERROR: input_number ${input_number} is illegal for input_base ${input_base}"
	exit 1
fi

echo "obase=${output_base}; ibase=${input_base}; $input_number" | bc