a tiny command line argument parser

entrance

#!/bin/sh
#
# Usage: 
#      source entrance "arg1 arg2 arg3" $*
#

readonly program=$(basename $0)
readonly args=($1)

shift 1
if [ $# -ne ${#args[@]} ]; then
  echo >&2 "Usage: ${program} $(IFS=' '; echo ${args[*]^^})"
  exit 1
fi

for arg in ${args[@]}; do
  eval "readonly ${arg}=$1"
  shift
done