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