Struct std::process::Stdio

pub struct Stdio(/* private fields */);

Describes what to do with a standard I/O stream for a child process when passed to the stdin, stdout, and stderr methods of Command.

Implementations

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impl Stdio

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pub fn piped() -> Stdio

A new pipe should be arranged to connect the parent and child processes.

Examples

With stdout:

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

let output = Command::new("echo")
    .arg("Hello, world!")
    .stdout(Stdio::piped())
    .output()
    .expect("Failed to execute command");

assert_eq!(String::from_utf8_lossy(&output.stdout), "Hello, world!\n");
// Nothing echoed to console

With stdin:

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

let mut child = Command::new("rev")
    .stdin(Stdio::piped())
    .stdout(Stdio::piped())
    .spawn()
    .expect("Failed to spawn child process");

let mut stdin = child.stdin.take().expect("Failed to open stdin");
std::thread::spawn(move || {
    stdin.write_all("Hello, world!".as_bytes()).expect("Failed to write to stdin");
});

let output = child.wait_with_output().expect("Failed to read stdout");
assert_eq!(String::from_utf8_lossy(&output.stdout), "!dlrow ,olleH");

Writing more than a pipe buffer’s worth of input to stdin without also reading stdout and stderr at the same time may cause a deadlock. This is an issue when running any program that doesn’t guarantee that it reads its entire stdin before writing more than a pipe buffer’s worth of output. The size of a pipe buffer varies on different targets.

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pub fn inherit() -> Stdio

The child inherits from the corresponding parent descriptor.

Examples

With stdout:

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

let output = Command::new("echo")
    .arg("Hello, world!")
    .stdout(Stdio::inherit())
    .output()
    .expect("Failed to execute command");

assert_eq!(String::from_utf8_lossy(&output.stdout), "");
// "Hello, world!" echoed to console

With stdin:

use std::process::{Command, Stdio};
use std::io::{self, Write};

let output = Command::new("rev")
    .stdin(Stdio::inherit())
    .stdout(Stdio::piped())
    .output()
    .expect("Failed to execute command");

print!("You piped in the reverse of: ");
io::stdout().write_all(&output.stdout).unwrap();

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pub fn null() -> Stdio

This stream will be ignored. This is the equivalent of attaching the stream to /dev/null.

Examples

With stdout:

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

let output = Command::new("echo")
    .arg("Hello, world!")
    .stdout(Stdio::null())
    .output()
    .expect("Failed to execute command");

assert_eq!(String::from_utf8_lossy(&output.stdout), "");
// Nothing echoed to console

With stdin:

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

let output = Command::new("rev")
    .stdin(Stdio::null())
    .stdout(Stdio::piped())
    .output()
    .expect("Failed to execute command");

assert_eq!(String::from_utf8_lossy(&output.stdout), "");
// Ignores any piped-in input

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pub fn makes_pipe(&self) -> bool

🔬This is a nightly-only experimental API. (stdio_makes_pipe #98288)

Returns true if this requires Command to create a new pipe.

Example

#![feature(stdio_makes_pipe)]
use std::process::Stdio;

let io = Stdio::piped();
assert_eq!(io.makes_pipe(), true);

Trait Implementations

1.16.0source

impl Debug for Stdio

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

Formats the value using the given formatter. Read more

1.20.0source

impl From<ChildStderr> for Stdio

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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"
);

1.20.0source

impl From<ChildStdin> for Stdio

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fn from(child: ChildStdin) -> Stdio

Converts a ChildStdin into a Stdio.

Examples

ChildStdin will be converted to Stdio using Stdio::from under the hood.

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

let reverse = Command::new("rev")
    .stdin(Stdio::piped())
    .spawn()
    .expect("failed reverse command");

let _echo = Command::new("echo")
    .arg("Hello, world!")
    .stdout(reverse.stdin.unwrap()) // Converted into a Stdio here
    .output()
    .expect("failed echo command");

// "!dlrow ,olleH" echoed to console

1.20.0source

impl From<ChildStdout> for Stdio

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fn from(child: ChildStdout) -> Stdio

Converts a ChildStdout into a Stdio.

Examples

ChildStdout will be converted to Stdio using Stdio::from under the hood.

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

let hello = Command::new("echo")
    .arg("Hello, world!")
    .stdout(Stdio::piped())
    .spawn()
    .expect("failed echo command");

let reverse = Command::new("rev")
    .stdin(hello.stdout.unwrap())  // Converted into a Stdio here
    .output()
    .expect("failed reverse command");

assert_eq!(reverse.stdout, b"!dlrow ,olleH\n");

1.20.0source

impl From<File> for Stdio

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fn from(file: File) -> Stdio

Converts a File into a Stdio.

Examples

File will be converted to Stdio using Stdio::from under the hood.

use std::fs::File;
use std::process::Command;

// With the `foo.txt` file containing "Hello, world!"
let file = File::open("foo.txt").unwrap();

let reverse = Command::new("rev")
    .stdin(file)  // Implicit File conversion into a Stdio
    .output()
    .expect("failed reverse command");

assert_eq!(reverse.stdout, b"!dlrow ,olleH");

1.63.0source

impl From<OwnedFd> for StdioAvailable on Unix only.

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fn from(fd: OwnedFd) -> Stdio

Converts to this type from the input type.

1.63.0source

impl From<OwnedHandle> for StdioAvailable on Windows only.

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fn from(handle: OwnedHandle) -> Stdio

Converts to this type from the input type.

1.74.0source

impl From<Stderr> for Stdio

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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());

1.74.0source

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());

1.2.0source

impl FromRawFd for StdioAvailable on Unix only.

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unsafe fn from_raw_fd(fd: RawFd) -> Stdio

Constructs a new instance of Self from the given raw file descriptor. Read more

1.2.0source

impl FromRawHandle for StdioAvailable on Windows only.

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unsafe fn from_raw_handle(handle: RawHandle) -> Stdio

Constructs a new I/O object from the specified raw handle. Read more

Auto Trait Implementations

impl RefUnwindSafe for Stdio

impl Send for Stdio

impl Sync for Stdio

impl Unpin for Stdio

impl UnwindSafe for Stdio

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>,

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>,

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.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/process/struct.Stdio.html

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Struct std::process::Stdio

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