Struct process_stream::Process

pub struct Process { /* private fields */ }

Thin Wrapper around Command to make it streamable

Implementations

impl Process

pub fn new<S: AsRef<OsStr>>(program: S) -> Self

Create new process with a program

pub fn stdin(&mut self, stdin: Stdio)

Set the process’s stdin.

pub fn stdout(&mut self, stdout: Stdio)

Set the process’s stdout.

pub fn stderr(&mut self, stderr: Stdio)

Set the process’s stderr.

pub fn abort(&self)

Abort the process

Methods from Deref<Target = Command>

pub fn as_std(&self) -> &Command

Cheaply convert to a &std::process::Command for places where the type from the standard library is expected.

pub fn arg<S>(&mut self, arg: S) -> &mut Command where
    S: AsRef<OsStr>, 

Adds an argument to pass to the program.

Only one argument can be passed per use. So instead of:

tokio::process::Command::new("sh")
  .arg("-C /path/to/repo");

usage would be:

tokio::process::Command::new("sh")
  .arg("-C")
  .arg("/path/to/repo");

To pass multiple arguments see args.

Examples

Basic usage:

use tokio::process::Command;

let command = Command::new("ls")
        .arg("-l")
        .arg("-a");

pub fn args<I, S>(&mut self, args: I) -> &mut Command where
    I: IntoIterator<Item = S>,
    S: AsRef<OsStr>, 

Adds multiple arguments to pass to the program.

To pass a single argument see arg.

Examples

Basic usage:

use tokio::process::Command;

let command = Command::new("ls")
        .args(&["-l", "-a"]);

pub fn env<K, V>(&mut self, key: K, val: V) -> &mut Command where
    K: AsRef<OsStr>,
    V: AsRef<OsStr>, 

Inserts or updates an environment variable mapping.

Note that environment variable names are case-insensitive (but case-preserving) on Windows, and case-sensitive on all other platforms.

Examples

Basic usage:

use tokio::process::Command;

let command = Command::new("ls")
        .env("PATH", "/bin");

pub fn envs<I, K, V>(&mut self, vars: I) -> &mut Command where
    I: IntoIterator<Item = (K, V)>,
    K: AsRef<OsStr>,
    V: AsRef<OsStr>, 

Adds or updates multiple environment variable mappings.

Examples

Basic usage:

use tokio::process::Command;
use std::process::{Stdio};
use std::env;
use std::collections::HashMap;

let filtered_env : HashMap<String, String> =
    env::vars().filter(|&(ref k, _)|
        k == "TERM" || k == "TZ" || k == "LANG" || k == "PATH"
    ).collect();

let command = Command::new("printenv")
        .stdin(Stdio::null())
        .stdout(Stdio::inherit())
        .env_clear()
        .envs(&filtered_env);

pub fn env_remove<K>(&mut self, key: K) -> &mut Command where
    K: AsRef<OsStr>, 

Removes an environment variable mapping.

Examples

Basic usage:

use tokio::process::Command;

let command = Command::new("ls")
        .env_remove("PATH");

pub fn env_clear(&mut self) -> &mut Command

Clears the entire environment map for the child process.

Examples

Basic usage:

use tokio::process::Command;

let command = Command::new("ls")
        .env_clear();

pub fn current_dir<P>(&mut self, dir: P) -> &mut Command where
    P: AsRef<Path>, 

Sets the working directory for the child process.

Platform-specific behavior

If the program path is relative (e.g., "./script.sh"), it’s ambiguous whether it should be interpreted relative to the parent’s working directory or relative to current_dir. The behavior in this case is platform specific and unstable, and it’s recommended to use canonicalize to get an absolute program path instead.

Examples

Basic usage:

use tokio::process::Command;

let command = Command::new("ls")
        .current_dir("/bin");

pub fn stdin<T>(&mut self, cfg: T) -> &mut Command where
    T: Into<Stdio>, 

Sets configuration for the child process’s standard input (stdin) handle.

Defaults to inherit when used with spawn or status, and defaults to piped when used with output.

Examples

Basic usage:

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

let command = Command::new("ls")
        .stdin(Stdio::null());

pub fn stdout<T>(&mut self, cfg: T) -> &mut Command where
    T: Into<Stdio>, 

Sets configuration for the child process’s standard output (stdout) handle.

Defaults to inherit when used with spawn or status, and defaults to piped when used with output.

Examples

Basic usage:

use tokio::process::Command;
use std::process::Stdio;

let command = Command::new("ls")
        .stdout(Stdio::null());

pub fn stderr<T>(&mut self, cfg: T) -> &mut Command where
    T: Into<Stdio>, 

Sets configuration for the child process’s standard error (stderr) handle.

Defaults to inherit when used with spawn or status, and defaults to piped when used with output.

Examples

Basic usage:

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

let command = Command::new("ls")
        .stderr(Stdio::null());

pub fn kill_on_drop(&mut self, kill_on_drop: bool) -> &mut Command

Controls whether a kill operation should be invoked on a spawned child process when its corresponding Child handle is dropped.

By default, this value is assumed to be false, meaning the next spawned process will not be killed on drop, similar to the behavior of the standard library.

Caveats

On Unix platforms processes must be “reaped” by their parent process after they have exited in order to release all OS resources. A child process which has exited, but has not yet been reaped by its parent is considered a “zombie” process. Such processes continue to count against limits imposed by the system, and having too many zombie processes present can prevent additional processes from being spawned.

Although issuing a kill signal to the child process is a synchronous operation, the resulting zombie process cannot be .awaited inside of the destructor to avoid blocking other tasks. The tokio runtime will, on a best-effort basis, attempt to reap and clean up such processes in the background, but makes no additional guarantees are made with regards how quickly or how often this procedure will take place.

If stronger guarantees are required, it is recommended to avoid dropping a Child handle where possible, and instead utilize child.wait().await or child.kill().await where possible.

pub fn uid(&mut self, id: u32) -> &mut Command

Sets the child process’s user ID. This translates to a setuid call in the child process. Failure in the setuid call will cause the spawn to fail.

pub fn gid(&mut self, id: u32) -> &mut Command

Similar to uid but sets the group ID of the child process. This has the same semantics as the uid field.

pub fn arg0<S>(&mut self, arg: S) -> &mut Command where
    S: AsRef<OsStr>, 

Sets executable argument.

Set the first process argument, argv[0], to something other than the default executable path.

pub unsafe fn pre_exec<F>(&mut self, f: F) -> &mut Command where
    F: 'static + FnMut() -> Result<(), Error> + Send + Sync, 

Schedules a closure to be run just before the exec function is invoked.

The closure is allowed to return an I/O error whose OS error code will be communicated back to the parent and returned as an error from when the spawn was requested.

Multiple closures can be registered and they will be called in order of their registration. If a closure returns Err then no further closures will be called and the spawn operation will immediately return with a failure.

Safety

This closure will be run in the context of the child process after a fork. This primarily means that any modifications made to memory on behalf of this closure will not be visible to the parent process. This is often a very constrained environment where normal operations like malloc or acquiring a mutex are not guaranteed to work (due to other threads perhaps still running when the fork was run).

This also means that all resources such as file descriptors and memory-mapped regions got duplicated. It is your responsibility to make sure that the closure does not violate library invariants by making invalid use of these duplicates.

When this closure is run, aspects such as the stdio file descriptors and working directory have successfully been changed, so output to these locations may not appear where intended.

pub fn spawn(&mut self) -> Result<Child, Error>

Executes the command as a child process, returning a handle to it.

By default, stdin, stdout and stderr are inherited from the parent.

This method will spawn the child process synchronously and return a handle to a future-aware child process. The Child returned implements Future itself to acquire the ExitStatus of the child, and otherwise the Child has methods to acquire handles to the stdin, stdout, and stderr streams.

All I/O this child does will be associated with the current default event loop.

Examples

Basic usage:

use tokio::process::Command;

async fn run_ls() -> std::process::ExitStatus {
    Command::new("ls")
        .spawn()
        .expect("ls command failed to start")
        .wait()
        .await
        .expect("ls command failed to run")
}

Caveats

Dropping/Cancellation

Similar to the behavior to the standard library, and unlike the futures paradigm of dropping-implies-cancellation, a spawned process will, by default, continue to execute even after the Child handle has been dropped.

The Command::kill_on_drop method can be used to modify this behavior and kill the child process if the Child wrapper is dropped before it has exited.

Unix Processes

On Unix platforms processes must be “reaped” by their parent process after they have exited in order to release all OS resources. A child process which has exited, but has not yet been reaped by its parent is considered a “zombie” process. Such processes continue to count against limits imposed by the system, and having too many zombie processes present can prevent additional processes from being spawned.

The tokio runtime will, on a best-effort basis, attempt to reap and clean up any process which it has spawned. No additional guarantees are made with regards how quickly or how often this procedure will take place.

It is recommended to avoid dropping a Child process handle before it has been fully awaited if stricter cleanup guarantees are required.

Errors

On Unix platforms this method will fail with std::io::ErrorKind::WouldBlock if the system process limit is reached (which includes other applications running on the system).

pub fn status(&mut self) -> impl Future<Output = Result<ExitStatus, Error>>

Executes the command as a child process, waiting for it to finish and collecting its exit status.

By default, stdin, stdout and stderr are inherited from the parent. If any input/output handles are set to a pipe then they will be immediately closed after the child is spawned.

All I/O this child does will be associated with the current default event loop.

The destructor of the future returned by this function will kill the child if kill_on_drop is set to true.

Errors

This future will return an error if the child process cannot be spawned or if there is an error while awaiting its status.

On Unix platforms this method will fail with std::io::ErrorKind::WouldBlock if the system process limit is reached (which includes other applications running on the system).

Examples

Basic usage:

use tokio::process::Command;

async fn run_ls() -> std::process::ExitStatus {
    Command::new("ls")
        .status()
        .await
        .expect("ls command failed to run")
}

pub fn output(&mut self) -> impl Future<Output = Result<Output, Error>>

Executes the command as a child process, waiting for it to finish and collecting all of its output.

Note: this method, unlike the standard library, will unconditionally configure the stdout/stderr handles to be pipes, even if they have been previously configured. If this is not desired then the spawn method should be used in combination with the wait_with_output method on child.

This method will return a future representing the collection of the child process’s stdout/stderr. It will resolve to the Output type in the standard library, containing stdout and stderr as Vec<u8> along with an ExitStatus representing how the process exited.

All I/O this child does will be associated with the current default event loop.

The destructor of the future returned by this function will kill the child if kill_on_drop is set to true.

Errors

This future will return an error if the child process cannot be spawned or if there is an error while awaiting its status.

On Unix platforms this method will fail with std::io::ErrorKind::WouldBlock if the system process limit is reached (which includes other applications running on the system).

Examples

Basic usage:

use tokio::process::Command;

async fn run_ls() {
    let output: std::process::Output = Command::new("ls")
        .output()
        .await
        .expect("ls command failed to run");
    println!("stderr of ls: {:?}", output.stderr);
}

Trait Implementations

impl Deref for Process

type Target = Command

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for Process

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl From<&Path> for Process

fn from(path: &Path) -> Self

Converts to this type from the input type.

impl From<&PathBuf> for Process

fn from(path: &PathBuf) -> Self

Converts to this type from the input type.

impl From<&str> for Process

fn from(path: &str) -> Self

Converts to this type from the input type.

impl From<Command> for Process

fn from(command: Command) -> Self

Converts to this type from the input type.

impl<S: AsRef<OsStr>> From<Vec<S, Global>> for Process

fn from(command_args: Vec<S>) -> Self

Converts to this type from the input type.

impl ProcessExt for Process

fn get_command(&mut self) -> &mut Command

Get command that will be used to create a child process from

fn aborter(&self) -> Option<Arc<Notify>>

Get a notifier that can be used to abort the process

fn set_aborter(&mut self, aborter: Option<Arc<Notify>>)

Set the notifier that should be used to abort the process

fn take_stdin(&mut self) -> Option<ChildStdin>

Get process stdin

fn set_child_stdin(&mut self, child_stdin: Option<ChildStdin>)

Set process stdin

fn get_stdin(&mut self) -> Option<Stdio>

Get process stdin pipe

fn get_stdout(&mut self) -> Option<Stdio>

get process stdout pipe

fn get_stderr(&mut self) -> Option<Stdio>

get process stderr pipe

fn command(&mut self) -> &mut Command

Get command after settings the required pipes;

fn spawn_and_stream(&mut self) -> Result<ProcessStream>

Spawn and stream process

fn _spawn_and_stream(&mut self) -> Result<ProcessStream>

Spawn and stream process (avoid custom implementation, use spawn_and_stream instead)