improve arg handling

Cargo.toml

@@ -5,6 +5,7 @@ license = "GPL-3.0"
 authors = ["jojii <jojii@gmx.net>"]
 repository = "https://github.com/JojiiOfficial/MediaD"
 description = "A Simple and lightweight daemon to handle keyboard media buttons easily"
+readme = "README.md"
 edition = "2018"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

src/main.rs

@@ -4,6 +4,15 @@ use mpris::PlayerFinder;
 use pulsectl::controllers::{DeviceControl, SinkController};
 
 fn main() {
+    if std::env::args().count() < 2 {
+        println!(
+            "Usage: {} <device-id>",
+            std::env::args().nth(0).unwrap_or("mediad".to_owned())
+        );
+
+        return;
+    }
+
     let device_path = std::env::args().nth(1).unwrap().to_owned();
     let mut device =
         evdev::Device::open(&Path::new("/dev/input/by-id").join(&device_path)).unwrap();