Transforms string into boolean value

string_to_bool.sh

function s_to_bool(){
  local s="${1}"
  [[ -n "${s}" ]] || return 1

  case "${s}" in
    [nN][oO]|[fF][aA][lL][sS][eE]|0)
      return 1;;
    *) return 0;;
  esac
}