Struct Stdout

pub struct Stdout { /* private fields */ }

Available on crate features dep_tokio and std only.

A handle to the standard output stream of a process.

Concurrent writes to stdout must be executed with care: Only individual writes to this AsyncWrite are guaranteed to be intact. In particular you should be aware that writes using write_all are not guaranteed to occur as a single write, so multiple threads writing data with write_all may result in interleaved output.

Created by the stdout function.

Examples

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

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut stdout = io::stdout();
    stdout.write_all(b"Hello world!").await?;
    Ok(())
}

The following is an example of using stdio with loop.

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

#[tokio::main]
async fn main() {
    let messages = vec!["hello", " world\n"];

    // When you use `stdio` in a loop, it is recommended to create
    // a single `stdio` instance outside the loop and call a write
    // operation against that instance on each loop.
    //
    // Repeatedly creating `stdout` instances inside the loop and
    // writing to that handle could result in mangled output since
    // each write operation is handled by a different blocking thread.
    let mut stdout = io::stdout();

    for message in &messages {
        stdout.write_all(message.as_bytes()).await.unwrap();
        stdout.flush().await.unwrap();
    }
}

Trait Implementations

impl AsFd for Stdout

fn as_fd(&self) -> BorrowedFd<'_>

Borrows the file descriptor.

impl AsRawFd for Stdout

fn as_raw_fd(&self) -> i32

Extracts the raw file descriptor.

impl AsyncWrite for Stdout

fn poll_write( self: Pin<&mut Stdout>, cx: &mut Context<'_>, buf: &[u8], ) -> Poll<Result<usize, Error>>

Attempt to write bytes from buf into the object.

fn poll_flush( self: Pin<&mut Stdout>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Attempts to flush the object, ensuring that any buffered data reach their destination.

fn poll_shutdown( self: Pin<&mut Stdout>, cx: &mut Context<'_>, ) -> Poll<Result<(), Error>>

Initiates or attempts to shut down this writer, returning success when the I/O connection has completely shut down.

fn poll_write_vectored( self: Pin<&mut Self>, cx: &mut Context<'_>, bufs: &[IoSlice<'_>], ) -> Poll<Result<usize, Error>>

Like poll_write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

Determines if this writer has an efficient poll_write_vectored implementation.

impl Debug for Stdout

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.