What variable values ​​in nginx give false?

Question

Nginx

In nginx, the following construction is possible:

if ($my_var) {
    ... 
}

What values ​​will give false?
""
"0"
?

Answer 1

https://nginx.org/ru/docs/http/ngx_http_rewrite_mo...

false values ​​of a variable are an empty string or "0";