<b_jonas> learn ayacc is ais523\'s yacc parser generator implementation, get it from (darcs clone http://nethack4.org/projects/ayacc) or a snapshot from "http://nethack4.org/pastebin/ayacc-2020-04.tar.gz".

#!/bin/bash
interp="$1"; script="$2"; shift 2; if [ "$#" -eq 1 ]; then printf '%s\n' "$1"; elif [ "$#" -eq 0 ]; then cat; fi | { shift; $interp "$script" "$@"; }