How to update a .war in Tomcat

I am new to Tomcat and following is the steps I am using to update a .war in Tomcat:

1. stop tomcat.
2. delete .war and the folder with same name in /webapps.
3. copy and paste my new .war in /webapps.
4. restart tomcat by ./bin/catalina.sh run.

However, the new .war always won't work. Seems it's the old version .war that is running.

In /conf/server.xml, I am using the following configs:

  <Host name="localhost"  appBase="webapps" unpackWARs="true" autoDeploy="true">

Can someone help me on this problem? Thanks!