# Child processes

The `process::Output` struct represents the output of a finished child process, and the `process::Command` struct is a process builder.

    use std::process::Command;

    fn main() {
        let output = Command::new("rustc")
            .arg("--version")
            .output().unwrap_or_else(|e| {
                panic!("failed to execute process: {}", e)
        });

        if output.status.success() {
            let s = String::from_utf8_lossy(&output.stdout);

            print!("rustc succeeded and stdout was:\n{}", s);
        } else {
            let s = String::from_utf8_lossy(&output.stderr);

            print!("rustc failed and stderr was:\n{}", s);
        }
    }

(You are encouraged to try the previous example with an incorrect flag passed to `rustc`)