If the Substitute variables in contents? option is set to Yes, Virtualmin will replace variables in all files except for images when copying them from the skeleton directory. However, this may break PHP or perl scripts which use the same format for variables as Virtualmin's template language.

To avoid this problem, you can enter a list of file patterns in this field, like `*.conf`. Only files matching those patterns and not the patterns in File patterns not to substitute will not have their contents modified.