在linux下安装好tomcat启动时报如下错误：

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

原因：找不到jdk或者jre路径。

解决办法：在setclasspath.bat的开头声明环境变量，打开tomcat的bin目录下面的setclasspath.sh，添加粗体部分，路径修改为自己机器jdk和jre路径即可

# -----------------------------------------------------------------------------

#  Set JAVA_HOME or JRE_HOME if not already set, ensure any provided settings

#  are valid and consistent with the selected start-up options and set up the

#  endorsed directory.

# -----------------------------------------------------------------------------

export JAVA_HOME=/usr/java/jdk1.8.0_151

export JRE_HOME=/usr/java/jdk1.8.0_151/jre

"setclasspath.sh" 99L, 3762C written

[root@iZ2ze6cj9rrq7y40sjtli9Z bin]# cd ..

[root@iZ2ze6cj9rrq7y40sjtli9Z apache-tomcat-8.5.24]# ls

bin  lib      logs    RELEASE-NOTES  temp    work

conf  LICENSE  NOTICE  RUNNING.txt    webapps

[root@iZ2ze6cj9rrq7y40sjtli9Z apache-tomcat-8.5.24]# cd bin/

[root@iZ2ze6cj9rrq7y40sjtli9Z bin]# ls