Tomcat servlet引擎没有运行，但是pid文件存在。这条信息是什么意思?如果我得到Tomcat，我需要恢复吗?

I am making a shell script to restart tomcat after crash. I wonder I need to handle this message in my script "Tomcat servlet engine is not running, but pid file exists." What does this message means? Do I need to take it into account as an error message that oblige me to restart Tomcat?I am making a shell script to restart tomcat af