启动tomcat时报如下的错：
Neither the JAVA_HOME nor the JRE_HOME environment variable is defined
At least one of these environment variable is needed to run this program
解决方法：编辑文件 /usr/local/tomcat/bin/catalina.sh (根据你自己的jdk路径进行修改) 在文件的正文开头，即正式代码前，大概在99行添加如下代码:
export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_231
export JRE_HOME=/usr/lib/jvm/jdk1.8.0_231/jre