Added very basic proof-of-concept

src/main.rs

@@ -0,0 +1,59 @@
+use std::io;
+use std::io::Write;
+use std::process::{Child, Command, Stdio};
+
+struct Server {
+    child: Child,
+}
+
+impl Server {
+    fn spawn() -> Server {
+        let child = Command::new("/usr/lib/jvm/java-16-openjdk/bin/java")
+            .arg("-jar")
+            .arg("paper-1.17.1-259.jar")
+            .arg("--universe")
+            .arg("worlds")
+            .arg("--nogui")
+            .stdin(Stdio::piped())
+            .spawn()
+            .expect("Couldn't start child process");
+
+        Server { child }
+    }
+
+    pub fn send_command(&mut self, cmd: &str) {
+        match cmd.trim() {
+            "stop" | "exit" => self.stop(),
+            s => self.custom(s),
+        }
+    }
+
+    fn custom(&mut self, cmd: &str) {
+        let mut stdin = self.child.stdin.as_ref().unwrap();
+        stdin.write_all(cmd.as_bytes()).unwrap();
+        stdin.flush().unwrap();
+    }
+
+    pub fn stop(&mut self) {
+        self.custom("stop");
+        self.child.wait();
+    }
+}
+
+fn main() {
+    let mut server = Server::spawn();
+
+    let stdin = io::stdin();
+    let input = &mut String::new();
+
+    loop {
+        input.clear();
+        stdin.read_line(input);
+        println!("input: {}", input.trim());
+        server.send_command(input);
+
+        if input.trim() == "stop" {
+            break;
+        }
+    }
+}