Lighttpd

server.document-root

document-root of the webserver

This variable has the specified as it will be used for all requests without a Host: header and for all with a know hostname which you might have specified with one of the above conditionals.

Default: no default, required

Only absolute paths (e.g. "/var/www/web/" are supported, relative paths (like ~/web or ./web) will most certainly lead to errors.