CGI (Common Gateway Interface). It is a way to communicate between browser and server. Simple scripts used to do simple tasks.



## Docs and References

You'll want to consult the [httpd](https://man.openbsd.org/httpd) and [[httpd.conf](/https://man.openbsd.org/httpd.conf) man pages to know about httpd config blocks.
You'll want to consult the [httpd](https://man.openbsd.org/httpd) and [[httpd.conf](/https://man.openbsd.org/httpd.conf) man pages to know about httpd config blocks.

## Writing the script

We will use C language to create the script.

Create the script at your home directory `/home/username/hello.c`



    #include <stdio.h>
    int main(void)
    {
       puts("Status: 200 OK\r");
       puts("Content-Type: text/html\r");
       puts("\r");
       puts("Hello, world!\n");
       return 0;
    }


Your script is ready, but you still need to compile it.

    $ cd /home/username
    $ cc hello.c -o hello.cgi
    $ doas mv hello.cgi /var/www/htdocs/yoursite/cgi-bin/


Make the script executable

    $ doas chmod +x /var/www/htdocs/yoursite/cgi-bin/hello.cgi


## Configuring httpd.conf

Add the cgi block to your /etc/httpd.conf block for your website. It should look like this:

    server "example.com" {
            listen on * port 80
            root "/htdocs/yoursite"
            connection max request body 104857600
            location "/cgi-bin/*"{
                    root "/htdocs/yoursite/"
                    fastcgi
            }
            location "/.well-known/acme-challenge/*" {
                    root "/acme"
                    request strip 2
            }
    }




**NOTE**: You must replace example.com with your own domain

Now any scripts that you add in ##STARTCODEBLOCK##
 /var/www/htdocs/yoursite/cgi-bin ##ENDCODEBLOCK##
 directory will be accessible by ##STARTCODEBLOCK##
 http://example.com/cgi-bin/scriptname ##ENDCODEBLOCK##


Make sure you edit the block accordingly if you are using [TLS](/https://wiki.ircnow.org/index.php?n=Openhttpd.Tls ).

enable the server to run the script, we will use [ Slowcgi ](/https://man.openbsd.org/slowcgi.8).

Enable and start slowcgi

    $ doas rcctl enable slowcgi
    $ doas rcctl start slowcgi
 

Enable and start httpd if you haven't already

    $ doas rcctl enable httpd
    $ doas rcctl start httpd


Go to `http://example.com/cgi-bin/hello.cgi` and you will see "Hello world" printed on your screen!