Resolution
All standard paths for apache directories are stored in Plesk configuraion file. Example can be found below:Note: all examples are taken from Plesk 8.x installations, so if you have older version paths can be different. You should check it on the server directly.
For RedHat based:
# grep HTTPD /etc/psa/psa.conf
HTTPD_VHOSTS_D /var/www/vhosts # Virtual hosts directory
HTTPD_CONF_D /etc/httpd/conf # Apache configuration files directory
HTTPD_INCLUDE_D /etc/httpd/conf.d # Apache include files directory
HTTPD_BIN_D /usr/bin # Apache binary files directory
HTTPD_LOG_D /var/log/httpd # Apache log files directory
HTTPD_SERVICE httpd # Apache startup script
For FreeBSD:
# grep HTTPD /etc/psa//psa.conf
HTTPD_VHOSTS_D /usr/local/www/vhosts # Virtual hosts directory
HTTPD_CONF_D /usr/local/etc/apache2 # Apache configuration files directory
HTTPD_INCLUDE_D /usr/local/etc/apache2/Includes # Apache include files directory
HTTPD_BIN_D /usr/local/sbin # Apache binary files directory
HTTPD_LOG_D /var/log # Apache log files directory
HTTPD_SERVICE apache2 # Apache startup script
For Debian and Ubuntu servers:
# grep HTTPD -r /etc/psa/psa.conf
HTTPD_VHOSTS_D /var/www/vhosts # Virtual hosts directory
HTTPD_CONF_D /etc/apache2 # Apache configuration files directory
HTTPD_INCLUDE_D /etc/apache2/conf.d # Apache include files directory
HTTPD_BIN_D /usr/bin # Apache binary files directory
HTTPD_LOG_D /var/log/apache2 # Apache log files directory
HTTPD_SERVICE apache2 # Apache startup script