In the previous article, “string truncation with Nginx if statement plus regular expression”, we introduced the use of if to truncate strings. This time, we will take a look at the logical use of if: What is the logical use, in the program and, or relations, is called logic.

Does NGINX support and and or of if or && and ||?

The answer is No. When you try this configuration, overloading nginx, nginx will report an error

    location = /test/ {
        default_type text/html;
        set $b 0;
        if ( $remote_addr != '' && $http_x_forwarded_for != '' ){
            set $b '1';
        }
        echo $b;
    }
[root@test-vm ~]# /usr/local/nginx/sbin/nginx -t
nginx: [emerg] invalid condition "$remote_addr" in /usr/local/nginx/conf/nginx.conf:60
configuration file /usr/local/nginx/conf/nginx.conf test failed

So how should we implement the logical relationship between and and or?

    location = /test_and/ {
        default_type text/html;
        set $a 0;
        set $b 0;
        if ( $remote_addr != '' ){
            set $a 1;
        }
        if ( $http_x_forwarded_for != '' ){
            set $a 1$a;
        }
        if ( $a = 11 ){
            set $b 1;
        }
        echo $b;
    }
    location = /test_or/ {
        default_type text/html;
        set $a 0;
        set $b 0;
        if ( $remote_addr != '' ){
            set $a 1;
        }
        if ( $http_x_forwarded_for != '' ){
            set $a 1;
        }
        if ( $a = 1 ){
            set $b 1;
        }
        echo $b;
    }