Stdout in std::io - Rust
Description: A handle to the global standard output stream of the current process.

## Stdout

# Struct Stdout

1.0.0 · Source

    pub struct Stdout { /* private fields */ }

Expand description

A handle to the global standard output stream of the current process.

Each handle shares a global buffer of data to be written to the standard output stream. Access is also synchronized via a lock and explicit control over locking is available via the `lock` method.

By default, the handle is line-buffered when connected to a terminal, meaning it flushes automatically when a newline (`\n`) is encountered. For immediate output, you can manually call the `flush` method. When the handle goes out of scope, the buffer is automatically flushed.

Created by the `io::stdout` method.

#### §Note: Windows Portability Considerations

When operating in a console, the Windows implementation of this stream does not support non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return an error.

In a process with a detached console, such as one using `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, the contained handle will be null. In such cases, the standard library’s `Read` and `Write` will do nothing and silently succeed. All other I/O operations, via the standard library or via raw Windows API calls, will fail.

## Implementations§

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### impl Stdout

1.0.0 · Source

#### pub fn lock(&self) -> StdoutLock<'static> ⓘ

Locks this handle to the standard output stream, returning a writable guard.

The lock is released when the returned lock goes out of scope. The returned guard also implements the `Write` trait for writing data.

##### §Examples

    use std::io::{self, Write};

    fn main() -> io::Result<()> {
        let mut stdout = io::stdout().lock();

        stdout.write_all(b"hello world")?;

        Ok(())
    }

## Trait Implementations§

1.63.0 · Source§

### impl AsFd for Stdout

Available on Unix or HermitCore or `target_os=trusty` or WASI or `target_os=motor` only.
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#### fn as_fd(&self) -> BorrowedFd<'_>

Borrows the file descriptor. Read more
1.21.0 · Source§

### impl AsRawFd for Stdout

Available on Unix or HermitCore or `target_os=trusty` or WASI or `target_os=motor` only.
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#### fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor. Read more
1.16.0 · Source§

### impl Debug for Stdout

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

Formats the value using the given formatter. Read more
1.74.0 · Source§

### impl From<Stdout> for Stdio

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#### fn from(inherit: Stdout) -> Stdio

Redirect command stdout/stderr to our stdout

##### §Examples

    #![feature(exit_status_error)]
    use std::io;
    use std::process::Command;

    let output = Command::new("whoami")
        .stdout(io::stdout())
        .output()?;
    output.status.exit_ok()?;
    assert!(output.stdout.is_empty());

1.70.0 · Source§

### impl IsTerminal for Stdout

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#### fn is_terminal(&self) -> bool

Returns `true` if the descriptor/handle refers to a terminal/tty. Read more
1.48.0 · Source§

### impl Write for &Stdout

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#### fn write(&mut self, buf: &[u8]) -> Result<usize>

Writes a buffer into this writer, returning how many bytes were written. Read more
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#### fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like `write`, except that it writes from a slice of buffers. Read more
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#### fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (`can_vector` #69941)
Determines if this `Write`r has an efficient `write_vectored` implementation. Read more
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#### fn flush(&mut self) -> Result<()>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
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#### fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer. Read more
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#### fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>

🔬This is a nightly-only experimental API. (`write_all_vectored` #70436)
Attempts to write multiple buffers into this writer. Read more
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#### fn write_fmt(&mut self, args: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered. Read more
1.0.0 · Source§

#### fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of `Write`. Read more
1.0.0 · Source§

### impl Write for Stdout

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#### fn write(&mut self, buf: &[u8]) -> Result<usize>

Writes a buffer into this writer, returning how many bytes were written. Read more
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#### fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like `write`, except that it writes from a slice of buffers. Read more
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#### fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (`can_vector` #69941)
Determines if this `Write`r has an efficient `write_vectored` implementation. Read more
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#### fn flush(&mut self) -> Result<()>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
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#### fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer. Read more
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#### fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>

🔬This is a nightly-only experimental API. (`write_all_vectored` #70436)
Attempts to write multiple buffers into this writer. Read more
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#### fn write_fmt(&mut self, args: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered. Read more
1.0.0 · Source§

#### fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Creates a “by reference” adapter for this instance of `Write`. Read more
1.9.0 · Source§

### impl RefUnwindSafe for Stdout

1.9.0 · Source§

### impl UnwindSafe for Stdout

## Auto Trait Implementations§

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### impl Freeze for Stdout

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### impl Send for Stdout

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### impl Sync for Stdout

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### impl Unpin for Stdout

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.