sync with plan 9
diff --git a/src/cmd/rc/rc.h b/src/cmd/rc/rc.h
index 3e79617..f95b528 100644
--- a/src/cmd/rc/rc.h
+++ b/src/cmd/rc/rc.h
@@ -80,6 +80,7 @@
 #define	HERE	4
 #define	DUPFD	5
 #define	CLOSE	6
+#define	RDWR	7
 struct var{
 	char *name;		/* ascii name */
 	word *val;	/* value */