Linux custom init and SIGTERM

Question

I try to build my own init with rust language.
this is my example code :

use std::process::Command;

fn main() {
    loop {
        println!("Welcome to custom operating system");
        let result = Command::new("/bin/sh")
            .spawn();

        match result {
            Ok(mut child) => {
                let _r = child.wait();
            }
            Err(_err) => {
                println!("Restart shell")
            }
        }
    }
}

Note: this code work on my custom kernel without any problem.
now i have a misunderstood about init and SIGTERM signal .
should i implement trap SIGTERM on my init or kernel handle it ?
I read man 2 kill but still i have confused .