From d3d496133f883bc12e0b600bef3c70450fa0f0c6 Mon Sep 17 00:00:00 2001
From: Pedro Bagatin <pedrobagatin@yahoo.com.br>
Date: Tue, 8 Oct 2019 09:27:25 +0900
Subject: [PATCH] added #include <unistd.h> to System.h

some users are facing problem when installing, a common solution is adding this line.
---
 include/System.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/System.h b/include/System.h
index b377b453d1..e05aa8eec4 100644
--- a/include/System.h
+++ b/include/System.h
@@ -25,6 +25,7 @@
 #include<string>
 #include<thread>
 #include<opencv2/core/core.hpp>
+#include <unistd.h>
 
 #include "Tracking.h"
 #include "FrameDrawer.h"