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Environment variables can be accessed via the syntax ${ENV[variable]}. The curly braces are mandatory. Note that variable names are case-sensitive and usually in UPPER CASE.
Example: To get the value of the OS environment variable "CATALINA_HOME", use ${ENV[CATALINA_HOME]}.
Dynamic Variables
Dynamic variables can be defined in the installation XML with the <variable> tag inside the <dynamicvariables> element. The value of dynamic variables will be evaluated every time a panel is switched, i.e. between the panels. Dynamic variables can have a condition which will be evaluated first. If it's true, the value would be assigned, otherwise nothing happens to the variable.
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