linux下，关闭和重启tomcat时报错：
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
我的tomcat以前是正常的，突然重启下tomcat时报了这个错，错误大致是环境变量不可用造成的，
在网上找了很久都是说要修改setclasspath.bat（该文件路径在tomcat的bin目录下）文件；在文件中加入JAVA_HOME和JRE_HOME的环境变量，
我也在该文件中加了如下：
rem Make sure prerequisite environment variables are set
rem In debug mode we need a real JDK (JAVA_HOME)
export JAVA_HOME=/usr/local/jdk1.7.0_79
export JRE_HOME=${JAVA_HOME}/jre
if ""%1"" == ""debug"" goto needJavaHome
rem Otherwise either JRE or JDK are fine
if not "%JRE_HOME%" == "" goto gotJreHome
if not "%JAVA_HOME%" == "" goto gotJavaHome
echo Neither the JAVA_HOME nor the JRE_HOME environment variable is defined
echo At least one of these environment variable is needed to run this program
goto exit
:needJavaHome
rem Check if we have a usable JDK
if "%JAVA_HOME%" == "" goto noJavaHome
if not exist "%JAVA_HOME%\bin\java.exe" goto noJavaHome
if not exist "%JAVA_HOME%\bin\javaw.exe" goto noJavaHome
if not exist "%JAVA_HOME%\bin\jdb.exe" goto noJavaHome
"setclasspath.bat" [dos] 97L, 3509C
保存好文件，再次运行./startup.sh
仍然报错：
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
崩溃了，网上就这么一种解决问题的方法；
突然我意识上闪出一个念头，前面使用tomcat也是正常的，会不会在linux在运行的内存里面丢失了JAVA_HOME和JRE_HOME
的环境变量参数，如果是那样，就重新写入/etc/profile环境变量就ok了。
接着我运行了#source /etc/profile
重新写入profile配置文件
运行#java -version
奇迹出现了
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)
切换到tomcat的bin目录下
运行#./startup.sh
tomcat运行成功！