diff --git a/README.md b/README.md
index 71a1b5c..e52d051 100644
--- a/README.md
+++ b/README.md
@@ -3,18 +3,17 @@
 Base on Ubuntu, using Docker to construct your Apt mirror HTTP server
 
 ## Usage
-Using default [mirror.list!](mirror.list)
-```
-docker run -v /path/data:/var/spool/apt-mirror \
-           -d -p port_number:80 seterrychen/apt-mirror-http-server
-```
-
-Using your mirror.list
+Running command
 ```
 docker run -v /path/data:/var/spool/apt-mirror \
            -v /path/your/mirror.list:/etc/apt/mirror.list \
+           -e TIMEOUT=timeout-value
            -d -p port_number:80 seterrychen/apt-mirror-http-server
 ```
+/path/data is where to store data, and the TIMEOUT var to repeatedly execute apt-mirror.
+
+If you don't setting variable of mirror.list and TIMEOUT, it will using the default [mirror.list](mirror.list), and
+the default TIMEOUT is 6 hours. To see the [TIMEOUT format description](http://www.cyberciti.biz/faq/linux-unix-sleep-bash-scripting/)
 
 ## Note
 It will take time to download, then start http server. Using ``docker logs -f container-id`` to check the process.
diff --git a/setup.sh b/setup.sh
index 5e80022..8466007 100755
--- a/setup.sh
+++ b/setup.sh
@@ -5,6 +5,7 @@ mkdir /var/www/package
 sed -i '12s/DocumentRoot \/var\/www\/html/DocumentRoot \/var\/www\/package/' /etc/apache2/sites-enabled/000-default.conf
 service apache2 restart
 
+UNIT=${TIMEOUT:-12h}
 while true; do
 
     # parse mirror.list to share under /var/www/package path
@@ -20,7 +21,8 @@ while true; do
         fi 
     done
 
-    printf "\n\n====== wait $TIMEOUT to execute apt-mirror command ======\n\n"
-    sleep $TIMEOUT
     apt-mirror
+    printf "\n\n====== wait $UNIT to execute apt-mirror again ======\n\n"
+    sleep $UNIT
+
 done