(I always forget what the magic numbers 0 through 2 means for the
"syslog" option.)
By the way: The "virtual_host" parameter is a bad name for that
particular option, I think. "Virtual host" signals that PostgreSQL will
behave differently according to which IP address it's contacted (like
Apache's virtual host support which makes the web-server serve different
sites according to different criteria). A better word for the options
would be "tcpip_listen_addr" or something like that.