Struct ChildStderr 

pub struct ChildStderr {
    inner: FileDesc,
}

A handle to a child process’s stderr.

This struct is used in the stderr field on Child.

When an instance of ChildStderr is dropped, the ChildStderr’s underlying file handle will be closed.

Fields

inner: FileDesc

Trait Implementations

impl AsFd for ChildStderr

Available on non-Hermit and (Unix) and not ((WebAssembly and non-WASI, or Fortanix and SGX)) only.

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

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

Borrows the file descriptor.

impl AsInner<FileDesc> for ChildStderr

fn as_inner(&self) -> &FileDesc

impl AsRawFd for ChildStderr

Available on non-Hermit and (Unix) and not ((WebAssembly and non-WASI, or Fortanix and SGX)) only.

fn as_raw_fd(&self) -> RawFd

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

Extracts the raw file descriptor.

impl CopyRead for ChildStderr

fn properties(&self) -> CopyParams

Extracts the file descriptor and hints/metadata, delegating through wrappers if necessary.

fn drain_to<W: Write>(&mut self, _writer: &mut W, _limit: u64) -> Result<u64>

Implementations that contain buffers (i.e. BufReader) must transfer data from their internal buffers into writer until either the buffers are emptied or limit bytes have been transferred, whichever occurs sooner. If nested buffers are present the outer buffers must be drained first.

fn taken(&mut self, _bytes: u64)

Updates Take wrappers to remove the number of bytes copied.

fn min_limit(&self) -> u64

The minimum of the limit of all Take<_> wrappers, u64::MAX otherwise. This method does not account for data BufReader buffers and would underreport the limit of a Take<BufReader<Take<_>>> type. Thus its result is only valid after draining the buffers via drain_to.

impl Debug for ChildStderr

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

Formats the value using the given formatter.

impl From<ChildStderr> for OwnedFd

Available on non-Hermit and (Unix) and not ((WebAssembly and non-WASI, or Fortanix and SGX)) only.

fn from(child_stderr: ChildStderr) -> OwnedFd

Takes ownership of a ChildStderr’s file descriptor.

impl From<ChildStderr> for Stdio

fn from(child: ChildStderr) -> Stdio

Converts a ChildStderr into a Stdio.

Examples

use std::process::{Command, Stdio};

let reverse = Command::new("rev")
    .arg("non_existing_file.txt")
    .stderr(Stdio::piped())
    .spawn()
    .expect("failed reverse command");

let cat = Command::new("cat")
    .arg("-")
    .stdin(reverse.stderr.unwrap()) // Converted into a Stdio here
    .output()
    .expect("failed echo command");

assert_eq!(
    String::from_utf8_lossy(&cat.stdout),
    "rev: cannot open non_existing_file.txt: No such file or directory\n"
);

impl From<OwnedFd> for ChildStderr

Available on non-Hermit and (Unix) and not ((WebAssembly and non-WASI, or Fortanix and SGX)) only.

Creates a ChildStderr from the provided OwnedFd.

The provided file descriptor must point to a pipe with the CLOEXEC flag set.

fn from(fd: OwnedFd) -> ChildStderr

Converts to this type from the input type.

impl FromInner<FileDesc> for ChildStderr

fn from_inner(pipe: FileDesc) -> ChildStderr

impl IntoInner<FileDesc> for ChildStderr

fn into_inner(self) -> FileDesc

impl IntoRawFd for ChildStderr

Available on non-Hermit and (Unix) and not ((WebAssembly and non-WASI, or Fortanix and SGX)) only.

fn into_raw_fd(self) -> RawFd

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

Consumes this object, returning the raw underlying file descriptor.

impl Read for ChildStderr

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

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Pull some bytes from this source into the specified buffer.

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

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

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

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Reads all bytes until EOF in this source, appending them to buf.

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

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Reads the exact number of bytes required to fill cursor.

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

where Self: Sized,

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

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R: Read>(self, next: R) -> Chain<Self, R>

where Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

fn read_array<const N: usize>(&mut self) -> Result<[u8; N]>

where Self: Sized,

🔬This is a nightly-only experimental API. (read_array #148848)

Read and return a fixed array of bytes from this source.