Starting Tomcat: some strangeness with CL, QShell scripting, and environment variables

You may recall that last week, I was going to great lengths to try and get a CL to automatically locate a Java 1.6 JVM, and set it in the job-level JAVA_HOME environment variable.

This is for a CL that starts Tomcat 7 (which requires Java 1.6 at minimum.

In resolving the crisis over the customer box on which Tomcat wasn't starting, I found that the "catalina.sh" script for Tomcat needed these lines (preferably in a separate "setenv.sh" file, rather than directly in "catalina.sh"):

# Java 6 settings if needed export -s JAVA_HOME=/QOpenSys/QIBM/ProdData/JavaVM/jdk60/32bit/jre export -s CATALINA_HOME=/wintouch/tomcat export -s JAVA_OPTS="-Dos400.awt.native=true -Djava.awt.headless=true -Djava.version=1.6 -Xms256m -Xmx512m"

But it seems that the very first line of this block is overriding the JAVA_HOME environment variable I'd so laboriously set in the CL program.

Which makes me wonder (1) if there's any actual reason to set JAVA_HOME both places, and (2) if I could set CATALINA_HOME and JAVA_OPTS in the CL, instead of the shell script, which would greatly simplify the installation.

Can anybody either shed some light on this, or point me to an appropriate document that would do so?

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JHHL