# borrowed from Apache
# (Could use $host instead of $server_name to log vhost aliases separately)
log_format vhost_combined '$server_name $remote_addr - $remote_user [$time_local] '
                          '"$request" $status $body_bytes_sent '
                          '"$http_referer" "$http_user_agent"';

# Define an access log for VirtualHosts that don't define their own logfile
access_log /var/log/nginx/other_vhosts_access.log vhost_combined