gistfile1.rs

use tokio::io::{AsyncReadExt, AsyncWriteExt};

#[tokio::main]
async fn main() {
    let mut child = tokio::process::Command::new("cat")
        .stdin(std::process::Stdio::piped())
        .stdout(std::process::Stdio::piped())
        .spawn()
        .expect("Failed to spawn cat process");

    child
        .stdin
        .as_mut()
        .unwrap()
        .write_all(b"Hello, world!")
        .await
        .unwrap();

    // can not pass eof to childprocess, will hang
    child.stdin.as_mut().unwrap().shutdown().await.unwrap();
    
    // will not hang
    // drop(child.stdin.take());

    let mut buffer = Vec::new();
    child
        .stdout
        .as_mut()
        .unwrap()
        .read_to_end(&mut buffer)
        .await
        .unwrap();
    println!("{}", String::from_utf8_lossy(&buffer));

    // Wait for the child to exit
    let status = child.wait().await.expect("Failed to wait for cat process");

    println!("Child process exited with status: {}", status);
}