菜鸟来求助 这玩意炸了

fn main() {
    let x: String = Command::new("ls").arg("").output().unwrap().stdout.convert_to_string();
}

pub trait ToString {
    fn convert_to_string(self) -> String;
}

impl ToString for Vec<u8> {
    fn convert_to_string(self) -> String {
	let mut output = String::new();
	for each in self {
            let c = each as char;
	    output.push_str(&c.to_string());
	}
	output
    }
}

thread 'main' panicked at 'called Result::unwrap() on an Err value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/libcore/result.rs:997:5