Qubit Command

Command-line process running utilities for Rust.

Overview

Qubit Command provides a small, structured API for running external programs, capturing their output, enforcing timeouts, and reporting command failures with clear error values.

Features

• Structured command execution with program and argument vectors
• Explicit shell command support for cases that require shell parsing
• Configurable timeout, working directory, stdin, environment variables, and success exit codes
• Process-tree termination on timeout using Unix process groups and Windows Job Objects
• UTF-8 stdout and stderr text accessors, with raw byte accessors for binary output
• Optional per-stream capture limits plus streaming tee files for large output
• Sanitized command diagnostics for sensitive argv values, explicit environment overrides, shell payloads, and caller-defined sensitive fields
• Typed errors for spawn failures, timeouts, failed output reads, and unexpected exit codes

Timeout Behavior

CommandRunner::new() does not enforce a timeout by default. Use timeout(Duration) when a command must be bounded, or without_timeout() when the absence of a timeout should be explicit in builder chains.

When a timeout is configured, the runner attempts to terminate the process tree: Unix commands are spawned in a new process group and Windows commands are spawned in a Job Object.

Large Output

By default stdout and stderr are captured without an in-memory byte limit. For commands that can emit large logs, configure capture limits and tee files:

use qubit_command::{Command, CommandRunner};

let output = CommandRunner::new()
    .max_output_bytes(64 * 1024)
    .tee_stdout_to_file("stdout.log")
    .tee_stderr_to_file("stderr.log")
    .run(Command::new("cargo").arg("test"))?;

if output.stdout_truncated() {
    eprintln!("stdout was truncated in memory; see stdout.log for the full stream");
}
# Ok::<(), Box<dyn std::error::Error>>(())

Quick Start

use std::time::Duration;

use qubit_command::{Command, CommandRunner};

let output = CommandRunner::new()
    .timeout(Duration::from_secs(10))
    .run(Command::new("git").args(&["status", "--short"]))?;

println!("{}", output.stdout_text()?);
# Ok::<(), Box<dyn std::error::Error>>(())

Shell Commands

Prefer structured commands whenever possible:

use qubit_command::{Command, CommandRunner};

let output = CommandRunner::new()
    .run(Command::new("printf").arg("hello"))?;

assert_eq!(output.stdout_text()?, "hello");
# Ok::<(), Box<dyn std::error::Error>>(())

Use Command::shell only when shell parsing, redirection, expansion, or pipes are intentional:

use qubit_command::{Command, CommandRunner};

let output = CommandRunner::new()
    .run(Command::shell("printf hello | tr a-z A-Z"))?;

assert_eq!(output.stdout_text()?, "HELLO");
# Ok::<(), Box<dyn std::error::Error>>(())

Sanitized Diagnostics

Command strings used in runner logs, CommandError::command(), and Command's Debug output are sanitized with qubit-sanitize. Sensitive structured argv values such as --password secret, --access-token=..., and OPENAI_API_KEY=... are masked. Explicit environment overrides are shown only in sanitized form. Command::shell payloads are treated as opaque shell scripts and displayed as <shell command> instead of being parsed.

Add application-specific fields on the runner when the defaults are not enough:

use qubit_command::{Command, CommandRunner, SensitivityLevel};

let error = CommandRunner::new()
    .sensitive_field("tenant_option", SensitivityLevel::Secret)
    .run(Command::new("__missing__").arg("--tenant-option").arg("secret"))
    .expect_err("sample command should fail");

assert_eq!(
    error.command(),
    r#"["__missing__", "--tenant-option", "<redacted>"]"#,
);

Runner-specific fields affect runner logs and CommandError::command(). Standalone Command Debug output has no runner context and uses the built-in defaults only.

Captured stdout/stderr bytes and tee files remain raw process output. Use capture limits and caller-side filtering when command output itself may contain secrets.

Output Text

stdout() and stderr() return raw bytes exactly as retained. Use stdout_text() and stderr_text() when the command output must be valid UTF-8. Use stdout_lossy_text() and stderr_lossy_text() to replace invalid UTF-8 bytes with �.

If the captured stdout or stderr contains invalid UTF-8, stdout_text() / stderr_text() return Err(str::Utf8Error) from str::from_utf8. The bytes are still stored on the returned CommandOutput; use stdout() / stderr() to read the raw output and decode or handle it yourself.

use qubit_command::{Command, CommandRunner};

let output = CommandRunner::new()
    .run(Command::shell("printf '\\377'"))?;

assert_eq!(output.stdout_lossy_text(), "\u{fffd}");
# Ok::<(), Box<dyn std::error::Error>>(())

Testing

A minimal local run:

cargo test
cargo clippy --all-targets --all-features -- -D warnings

To mirror what continuous integration enforces, run the repository scripts from the project root: ./align-ci.sh brings local tooling and configuration in line with CI, then ./ci-check.sh runs the same checks the pipeline uses. For test coverage, use ./coverage.sh to generate or open reports (see the script’s help and any project coverage notes for options such as HTML or JSON).

Contributing

Issues and pull requests are welcome.

• Open an issue for bug reports, design questions, or larger feature proposals when it helps align on direction.
• Keep pull requests scoped to one behavior change, fix, or documentation update when practical.
• Before submitting, run ./align-ci.sh and then ./ci-check.sh so your branch matches CI rules and passes the same checks as the pipeline. When you need to review or improve coverage, use ./coverage.sh as described under Testing.
• Add or update tests when you change runtime behavior, and update this README (or public rustdoc) when user-visible API behavior changes.

By contributing, you agree to license your contributions under the Apache License, Version 2.0, the same license as this project.

License

Copyright © 2026 Haixing Hu, Qubit Co. Ltd.

This project is licensed under the Apache License, Version 2.0. See the LICENSE file in the repository for the full text.

Author

Haixing Hu — Qubit Co. Ltd.