cd /var/www/asaisla.to.cnr.it/ drush dl xmlsitemap drush -u 1 en xmlsitemap xmlsitemap_custom xmlsitemap_menu xmlsitemap_node
cd sites/all/modules/ git clone https://github.com/Islandora/islandora_xmlsitemap drush -u 1 en islandora_xmlsitemap
Check
chown -R www-data:www-data sites/default/files/xmlsitemap