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 are handled for you the Right Way™.
Run a command without capturing any output. Here “hi” is printed directly to the terminal:
use duct::cmd; cmd!("echo", "hi").run()?;
Capture the standard output of a command. Here “hi” is returned as a
let stdout = cmd!("echo", "hi").read()?; assert_eq!(stdout, "hi");
Capture the standard output of a pipeline:
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:
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:
let result = cmd!("false").run(); assert!(result.is_err()); let result = cmd!("false").unchecked().run(); assert!(result.is_ok());
Unix-specific extensions to duct, for sending signals.
Create a command with any number of of positional arguments, which may be different types (anything that implements
Into<OsString>). See also the
cmdfunction, which takes a collection of arguments.
An incremental reader created with the
An implementation detail of
cmd, to distinguish paths from other string types.