# duct.rs [](https://github.com/oconnor663/duct.rs/actions) [](https://crates.io/crates/duct) [](https://docs.rs/duct)
Duct is a library for running child processes. Duct makes it easy to build
pipelines and redirect IO like a shell. At the same time, Duct helps you
write correct, portable code: whitespace is never significant, errors from
child processes get reported by default, and a variety of [gotchas, bugs,
and platform
inconsistencies](https://github.com/oconnor663/duct.py/blob/master/gotchas.md)
are handled for you the Right Way™.
- [Documentation](https://docs.rs/duct)
- [Crate](https://crates.io/crates/duct)
- [GitHub repo](https://github.com/oconnor663/duct.rs)
- [the same library, in Python](https://github.com/oconnor663/duct.py)
Examples
--------
Run a command without capturing any output. Here "hi" is printed directly
to the terminal:
```rust
use duct::cmd;
cmd!("echo", "hi").run()?;
```
Capture the standard output of a command. Here "hi" is returned as a
`String`:
```rust
let stdout = cmd!("echo", "hi").read()?;
assert_eq!(stdout, "hi");
```
Capture the standard output of a pipeline:
```rust
let stdout = cmd!("echo", "hi").pipe(cmd!("sed", "s/i/o/")).read()?;
assert_eq!(stdout, "ho");
```
Merge standard error into standard output and read both incrementally:
```rust
use duct::cmd;
use std::io::prelude::*;
use std::io::BufReader;
let big_cmd = cmd!("bash", "-c", "echo out && echo err 1>&2");
let reader = big_cmd.stderr_to_stdout().reader()?;
let mut lines = BufReader::new(reader).lines();
assert_eq!(lines.next().unwrap()?, "out");
assert_eq!(lines.next().unwrap()?, "err");
```
Children that exit with a non-zero status return an error by default:
```rust
let result = cmd!("false").run();
assert!(result.is_err());
let result = cmd!("false").unchecked().run();
assert!(result.is_ok());
```