diff --git a/rc/bin/E b/rc/bin/E
new file mode 100755
index 000000000..e91d4f6a2
--- /dev/null
+++ b/rc/bin/E
@@ -0,0 +1,16 @@
+#!/bin/rc
+# E file - B file, wait until it changes, exit
+rfork e
+if (! ~ $#* 1) {
+	echo usage: $0 file >[1=2]
+	exit usage
+}
+if (! test -e $1) {
+	echo $0: $1: no such file >[1=2]
+	exit no-file
+}
+otm = `{mtime $1 | awk '{print $1}'}
+B $1
+while (~ $otm `{mtime $1 | awk '{print $1}'})
+	sleep 1
+exit ''