diff --git a/s/pull b/s/pull
new file mode 100755
index 000000000..fa3167c5b
--- /dev/null
+++ b/s/pull
@@ -0,0 +1,5 @@
+#!/bin/sh
+if [ ! -z $1 ]; then
+  git checkout $1
+fi
+git pull && git submodule update