a) yourinstallationfolder/admin/geninvoice.php
an example could be
/usr/bin/php -q /home/EasyBiller/public_html/
yourinstallationfolder/admin/geninvoice.php
b) yourinstallationfolder/admin/geninvoice_attempt.php
an example could be
/usr/bin/php -q /home/EasyBiller/public_html/
yourinstallationfolder/admin/geninvoice_attempt.php