The absolute path of a domain is:

/web/htdocs/www.tuodominio.ext/home/

Therefore, by entering a file with the name nome_file.ext in the root of the domain, its absolute path will be: /web/htdocs/www.tuodominio.ext/home/nome_file.ext

For Third Level domains, the absolute path is:

/web/htdocs/nometerzolivello.nomedominio.ext/home/


For further details use the provided guide:  Perl Files and CHMOD Permissions