14 releases
0.3.0-alpha.2 | Aug 19, 2019 |
---|---|
0.2.5 | Feb 5, 2020 |
0.2.4 | Jun 22, 2019 |
0.2.3 | Nov 2, 2018 |
0.1.0 | Sep 10, 2016 |
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SLoC
tokio-process
An implementation of process management for Tokio
License
This project is licensed under the MIT license.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tokio by you, shall be licensed as MIT, without any additional terms or conditions.
lib.rs
:
An implementation of asynchronous process management for Tokio.
This crate provides a Command struct that imitates the interface of the
std::process::Command
type in the standard library, but provides asynchronous versions of
functions that create processes. These functions (spawn
, status
, output
and their
variants) return "future aware" types that interoperate with Tokio. The asynchronous process
support is provided through signal handling on Unix and system APIs on Windows.
Examples
Here's an example program which will spawn echo hello world
and then wait
for it complete.
#![feature(async_await)]
use tokio_process::Command;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
// The usage is the same as with the standard library's `Command` type, however the value
// returned from `spawn` is a `Result` containing a `Future`.
let child = Command::new("echo").arg("hello").arg("world")
.spawn();
// Make sure our child succeeded in spawning and process the result
let future = child.expect("failed to spawn");
// Await until the future (and the command) completes
let status = future.await?;
println!("the command exited with: {}", status);
Ok(())
}
Next, let's take a look at an example where we not only spawn echo hello world
but we also capture its output.
#![feature(async_await)]
use tokio_process::Command;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
// Like above, but use `output` which returns a future instead of
// immediately returning the `Child`.
let output = Command::new("echo").arg("hello").arg("world")
.output();
let output = output.await?;
assert!(output.status.success());
assert_eq!(output.stdout, b"hello world\n");
Ok(())
}
We can also read input line by line.
#![feature(async_await)]
use futures_util::stream::StreamExt;
use std::process::{Stdio};
use tokio::codec::{FramedRead, LinesCodec};
use tokio_process::Command;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let mut cmd = Command::new("cat");
// Specify that we want the command's standard output piped back to us.
// By default, standard input/output/error will be inherited from the
// current process (for example, this means that standard input will
// come from the keyboard and standard output/error will go directly to
// the terminal if this process is invoked from the command line).
cmd.stdout(Stdio::piped());
let mut child = cmd.spawn()
.expect("failed to spawn command");
let stdout = child.stdout().take()
.expect("child did not have a handle to stdout");
let mut reader = FramedRead::new(stdout, LinesCodec::new());
// Ensure the child process is spawned in the runtime so it can
// make progress on its own while we await for any output.
tokio::spawn(async {
let status = child.await
.expect("child process encountered an error");
println!("child status was: {}", status);
});
while let Some(line) = reader.next().await {
println!("Line: {}", line?);
}
Ok(())
}
Caveats
While similar to the standard library, this crate's Child
type differs
importantly in the behavior of drop
. In the standard library, a child
process will continue running after the instance of std::process::Child
is dropped. In this crate, however, because tokio_process::Child
is a
future of the child's ExitStatus
, a child process is terminated if
tokio_process::Child
is dropped. The behavior of the standard library can
be regained with the Child::forget
method.
Dependencies
~3.5MB
~60K SLoC