求这个代码的意思

zxy52155

if (-d $request_filename) {
rewrite ^/(.*)([^/])$ $scheme://$host/$1$2/ permanent;
}
ssi on;
ssi_silent_errors on;
ssi_types text/shtml;
location ~ /\.ht {
        return 403;
}
location ~ ssl.(key|crt)$ {
        return 403;
}
location ~ (favicon.ico|robots.txt) {
        expires 1d;
        log_not_found off;
        break;
}