Struct Stderr 

pub struct Stderr { /* private fields */ }

A handle to the standard error stream of a process.

For more information, see the io::stderr 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

impl Stderr

pub fn lock(&self) -> StderrLock<'static>

Locks this handle to the standard error 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 foo() -> io::Result<()> {
    let stderr = io::stderr();
    let mut handle = stderr.lock();

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

    Ok(())
}

Trait Implementations

impl AsFd for Stderr

Available on Hermit or Motor OS or Trusty or Unix or WASI only.

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

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Borrows the file descriptor.

impl AsHandle for Stderr

Available on Windows only.

fn as_handle(&self) -> BorrowedHandle<'_>

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Borrows the handle.

impl AsRawFd for Stderr

Available on Hermit or Motor OS or Trusty or Unix or WASI only.

fn as_raw_fd(&self) -> RawFd

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Extracts the raw file descriptor.

impl AsRawHandle for Stderr

Available on Windows only.

fn as_raw_handle(&self) -> RawHandle

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Extracts the raw handle.

impl Debug for Stderr

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

Formats the value using the given formatter.

impl From<Stderr> for Stdio

fn from(inherit: Stderr) -> Stdio

Redirect command stdout/stderr to our stderr

Examples

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

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

impl IsTerminal for Stderr

fn is_terminal(&self) -> bool

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Returns true if the descriptor/handle refers to a terminal/tty.

impl RefUnwindSafe for Stderr

impl StdioExt for Stderr

Available on Unix only.

fn set_fd<T: Into<OwnedFd>>(&mut self, fd: T) -> Result<()>

🔬This is a nightly-only experimental API. (stdio_swap #150667)

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Redirects the stdio file descriptor to point to the file description underpinning fd.

fn take_fd(&mut self) -> Result<OwnedFd>

🔬This is a nightly-only experimental API. (stdio_swap #150667)

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Redirects the stdio file descriptor to the null device (/dev/null) and returns a new OwnedFd backed by the previous file description.

fn replace_fd<T: Into<OwnedFd>>(&mut self, replace_with: T) -> Result<OwnedFd>

🔬This is a nightly-only experimental API. (stdio_swap #150667)

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Redirects the stdio file descriptor and returns a new OwnedFd backed by the previous file description.

impl UnwindSafe for Stderr

impl Write for Stderr

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

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

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

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Writer has an efficient write_vectored implementation.

fn flush(&mut self) -> Result<()>

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

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

Attempts to write an entire buffer into this writer.

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.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl Write for &Stderr

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

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

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

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Writer has an efficient write_vectored implementation.

fn flush(&mut self) -> Result<()>

This item is validated for IEC 61508 (SIL 2) and ISO 26262 (ASIL B).

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

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

Attempts to write an entire buffer into this writer.

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.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.