-C) builder="$2"; shift;; # custom build command
-G) builder="gmake %s";;
-M) builder="mk -a %s";; # use plan-9 mk (better, but sadly not widly used)
-C) builder="$2"; shift;; # custom build command
-G) builder="gmake %s";;
-M) builder="mk -a %s";; # use plan-9 mk (better, but sadly not widly used)