Setting Apache Tomcat JRE_HOME Without Environment Variable

environment-variablestomcat

I have a server which uses Java 6 for an Oracle implementation. But I want to install a Tomcat Apache Server on it but with Java 8. So in order to not mix the system environment here's what I want to do:

-Get Apache Tomcat and JRE/JDK as zip formats. Extract them on a folder and tell my Apache Tomcar to use that JRE/JDK.

AFAIK. I can edit the JAVA_HOME and JAVA_JRE in the catalina.bat file and I am now trying it on a laptop. I set my catalina.bat file but when I try to run the apache server through command prompt I get the message "Neither the JAVA_HOME or JRE_HOME environment variables are defined(…)"

This is my catalina.bat file after I edited it.

echo Using CATALINA_BASE:   "%CATALINA_BASE%"
echo Using CATALINA_HOME:   "%CATALINA_HOME%"
echo Using CATALINA_TMPDIR: "%CATALINA_TMPDIR%"
if ""%1"" == ""debug"" goto use_jdk
echo Using JRE_HOME:        "D:\ANDRES\Descargas\apache-tomcat-8.5.43-windows-x64\jre1.8.0_221\"
goto java_dir_displayed
:use_jdk
echo Using JAVA_HOME:       "D:\ANDRES\Descargas\apache-tomcat-8.5.43-windows-x64\jdk1.8.0_221\"
:java_dir_displayed
echo Using CLASSPATH:       "%CLASSPATH%"

So my question overall is. Is there a way to set the Tomcat server to use JRE_HOME from another route that is not defined on the system environment variables?

Best Answer

No need to modify catalina.bat. You can do that by setting the variables in the setenv script of your Tomcat installation. You seem to be using Windows, so here is an example of a setenv.bat to change JRE_HOME and JAVA_HOME.

Create the file %CATALINA_BASE%\bin\setenv.bat with the following content:

set "JRE_HOME=D:\ANDRES\Descargas\apache-tomcat-8.5.43-windows-x64\jre1.8.0_221"
set "JAVA_HOME=D:\ANDRES\Descargas\apache-tomcat-8.5.43-windows-x64\jdk1.8.0_221"
exit /b 0

This way, only Tomcat will be affected by the change in variables, all other processes use %PATH% and system global variables as always.

setenv is described in the Tomcat docs, chapter 3.2

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