tomcat shutdown后，进程还存在linux系统中的解决办法
1、修改bin/catalina.sh文件
查找PRGDIR=`dirname "$PRG"` 这一行；
在这一行的下面增加如下3行语句：
if [ -z "$CATALINA_PID" ]; then CATALINA_PID=$PRGDIR/CATALINA_PID fi
功能：判断 CATALINA_PID有没有配置，
没有的话，就使用当前目录（bin）
的CATALINA_PID文件来记录tomcat的进程ID
2、修改tomcat的shutdown.sh文件,在最后一行加上“-force”:
找到命令行： exec "$PRGDIR"/"$EXECUTABLE" stop "$@"
修改为：exec "$PRGDIR"/"$EXECUTABLE" stop -force "$@"
保存即可。
3、关闭tomcat时效果如下：
#./startup.sh
Using CATALINA_BASE: /opt/apps/tomcat9-www
Using CATALINA_HOME: /opt/apps/tomcat9-www
Using CATALINA_TMPDIR: /opt/apps/tomcat9-www/temp
Using JRE_HOME: /opt/apps/jdk1.8.0_181
Using CLASSPATH: /opt/apps/tomcat9-www/bin/bootstrap.jar:/opt/apps/tomcat9-www/bin/tomcat-juli.jar
Using CATALINA_PID: /opt/apps/tomcat9-www/bin/CATALINA_PID
Tomcat started.
#./shutdown.sh
Using CATALINA_BASE: /opt/apps/tomcat9
Using CATALINA_HOME: /opt/apps/tomcat9
Using CATALINA_TMPDIR: /opt/apps/tomcat9/temp
Using JRE_HOME: /opt/apps/jdk1.8.0_181
Using CLASSPATH: /opt/apps/tomcat9/bin/bootstrap.jar:/opt/apps/tomcat9-xtservice-app/bin/tomcat-juli.jar
Using CATALINA_PID: /opt/apps/tomcat9/bin/CATALINA_PID
Tomcat did not stop in time.
To aid diagnostics a thread dump has been written to standard out.
Killing Tomcat with the PID: 20618
The Tomcat process has been killed.