CLI Guidelines: Write Better Command-Line Apps

When you build a command-line interface (CLI) program, it’s not enough that it works - it should be clear, consistent, and human-friendly. The project Command Line Interface Guidelines (“CLIG.dev”) offers an open-source guide to help you write better CLI tools by taking traditional UNIX design principles and updating them for the modern day. (clig.dev)

Core Philosophy of CLIG.dev ​

This guide stands on a set of strong design principles that shape great CLIs. Key ideas include:

• Human-first design - Rather than machines, build the CLI for people.
• Consistency - Follow familiar patterns so users feel comfortable.
• Ease of discovery - Make commands intuitive and self-documenting.
• Empathy & Robustness - Handle errors kindly; assume real users, not just developers.

What CLIG.dev Covers: Key Topics ​

The guide dives into many important areas for CLI programs, including:

• The Basics: Standard I/O, exit codes, pipelines
• Help & Documentation: How to offer clear help text and guides
• Output & Errors: Formatting, verbosity, and error handling
• Arguments & Flags: Naming, structure, long vs short forms
• Interactivity, Subcommands & Configuration
• Environment Variables, Naming conventions, Distribution & Analytics

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Best Practices for CLI Tools from CLIG.dev ​

Here are some actionable guidelines you can apply right now:

1. Use clear, consistent flags​

Use -h, --help, --version. Use long-form flags when clarity matters.

2. Design subcommands when your tool has multiple modes​

For example, mytool add, mytool remove. It improves discoverability and structure.

3. Separate stdout and stderr​

Normal output goes to stdout, errors go to stderr. This helps piping, redirection, and automation.

4. Offer helpful error messages​

Explain what went wrong and how to fix it. Don’t just dump a stack trace.

5. Provide good documentation and help​

Include a --help command, usage examples, and a README describing common use cases.

6. Follow naming conventions​

Keep command names short, memorable, and meaningful. Avoid conflicts.

7. Make configuration predictable​

Allow settings via config files and environment variables. Prioritize consistently.

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Why Use CLIG.dev for Your Projects? ​

• It brings together decades of UNIX CLI wisdom and modern best-practices.
• It’s language-agnostic - you can apply it whether you write a CLI in Python, Go, Rust, or Bash.
• It prevents common usability mistakes and promotes tools that feel polished and professional.

Final Thoughts: Build CLIs That Users Love ​

Your CLI program shouldn’t just work - it should feel right. By following the CLIG.dev guide, you’ll build tools that are discoverable, reliable, and a joy to use. Whether you’re writing a small utility or a full-scale CLI app, these guidelines help you make design decisions with purpose.

Make your next CLI tool one that users come back to, not one they avoid.