#! /bin/sh cmd=${1%% *} [ "$cmd" = "$1" ] || args=${1#* } case $cmd in .calc) printf "%s = " "$args" echo "$args" | bc -l ;; .units) src=$(printf "%s" "$args" | sed 's/ ->.*//') dst=$(printf "%s" "$args" | sed 's/.*-> //') units -1 -v -- "$src" "$dst" ;; *) exit 1 ;; esac