CLI Development

Purpose

Build command-line tools that behave the way the shell expects: composable, scriptable, quiet by default, and honest about failure.

When to Use

• Building a developer tool, deployment script, or internal utility with a CLI.
• Designing the argument surface of an existing tool.
• Making a tool safe to use inside pipelines and CI.

Capabilities

• Argument and subcommand design.
• Correct use of stdout, stderr, and exit codes.
• Configuration precedence: flags, environment, config file, defaults.
• Human output versus machine output (--json, TTY detection).
• Progress, colour, and interactivity that degrade correctly when piped.