ref: ce64a58e70f0d6848ce946f99de5ca3059a0fb1f dir: /sys/src/ape/cmd/expr/mkfile/
APE=/sys/src/ape <$APE/config TARG=expr OFILES=y.tab.$O YFILES=expr.y HFILES=regexp.h BIN=$APEBIN </sys/src/cmd/mkone YFLAGS=-S CFLAGS=-B -c