From 83d78da153532be47097147957e083df3f59fda3 Mon Sep 17 00:00:00 2001
From: wangyang59 <wangyang59@baidu.com>
Date: Mon, 12 Dec 2016 11:52:18 -0800
Subject: [PATCH] add submodule instructions in build_and_install doc

---
 .../build_and_install/build_from_source_en.md          | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/doc/getstarted/build_and_install/build_from_source_en.md b/doc/getstarted/build_and_install/build_from_source_en.md
index 3771d316a..547742a4b 100644
--- a/doc/getstarted/build_and_install/build_from_source_en.md
+++ b/doc/getstarted/build_and_install/build_from_source_en.md
@@ -14,6 +14,16 @@ cd paddle
 git submodule update --init --recursive
 ```
 
+If you already have a local PaddlePaddle repo and have not initialized the submodule, you can simply run the following command in your PaddlePaddle home directory.
+```
+git submodule update --init --recursive
+```
+
+To sync with the upstream submodule repo, you can run the following command
+```
+git submodule update --remote
+```
+
 ## <span id="requirements">Requirements</span>
 
 To compile the source code, your computer must be equipped with the following dependencies.
-- 
GitLab