Thanks to John Cummings.

src/cmd/upas/fs/mkfile.9

@@ -0,0 +1,27 @@
+</$objtype/mkfile
+
+TARG=	fs\
+
+OFILES=\
+	fs.$O\
+	imap4.$O\
+	mbox.$O\
+	plan9.$O\
+	pop3.$O\
+	strtotm.$O\
+
+LIB=../common/libcommon.a$O\
+
+HFILES= ../common/common.h\
+	dat.h
+
+BIN=/$objtype/bin/upas
+
+UPDATE=\
+	mkfile\
+	$HFILES\
+	${TARG:%=%.c}\
+	${OFILES:%.$O=%.c}\
+
+</sys/src/cmd/mkone
+CFLAGS=$CFLAGS -I/sys/include -I../common