Within the same configuration file, virt_template.conf there is the <Custom Template> section. In this section, you can specify what shell commands should be executed after virt_template.pl does all the copying of the files from the <Template> section. An example may be:
cp -a /lib !!template
The !!template will be replaced by virt_template.pl and it indicates the template directory. Therefore, the above is stating: cp -a /lib /virtual/template (if we choose to stick to the directory defaults). This section is for you to customise the template directory even further than the <Template> section.
