Variable replacement at compile time or run time?

[DavidPerezIngeniero]

The doc states the following:

You can define any number of variables. If the plugin logic encounters a variable that isn’t defined, 
it simply replaces the variable reference with an empty string (like bash does).

But some variables like $INSTALL_PATH, aren't handled this way.

I have some variables that are entered by the user, like some custom destination directories:

        <fileset dir="tmp" targetdir="$dirWeb" override="true">
            <include name="js/**"/>
            <exclude name="js/**/*uncompressed*"/>
            <exclude name="js/build-report.txt"/>
            <exclude name="**/README"/>
        </fileset>

In this example, I don't want the variable $dirWeb to be replaced by a blank, but let IzPack do the substitution at run time. I need to be handled exactly like INSTALL_PATH.

How can this be done?

[DavidPerezIngeniero]

Byt playing a little, I've discovered the needed syntax:

fileset:
     includes: \$dirWeb

The dollar sign must be escaped with a backslash.

This SHOULD be documented.