#!/usr/bin/env bash

rgb () {
  declare g
  declare b
  case ${#1} in
    6) r=$"0x${1:0:2}"; g=$"0x${1:2:2}"; b=$"0x${1:4:2}";;
    3) rgb "${1:0:1}${1:0:1}${1:1:1}${1:1:1}${1:2:1}${1:2:1}"
        return;;
    1) rgb "$1$1$1"; return;;
    *) return 1;;
  esac
  #printf '\033[38;2;%i;%i;%im' $r $g $b 
  printf "%i;%i;%i\n" $r $g $b 
}

rgb $*