cli-developer

Use typer or click to define subcommands with decorators, where each function becomes a command with typed arguments and options. Typer generates help text automatically from type hints and docstrings, while click offers explicit decorator-based configuration.

Commander.js is the recommended choice for most Node.js CLIs, offering subcommands, options parsing, and TypeScript support. Yargs is an alternative when you need middleware support and more advanced argument validation.

Cobra, click, and typer all have built-in completion generation for bash, zsh, and fish. Run the framework's completion command to output the script, then source it or install it into the shell's completion directory.

ANSI color codes corrupt output when piped to files or other programs, so detect TTY status before applying colors. Check process.stdout.isTTY in Node.js, sys.stdout.isatty() in Python, or term.IsTerminal() in Go, and respect the NO_COLOR environment variable.

Register a SIGINT handler that prints a cancellation message and exits with code 130, the POSIX convention for SIGINT termination. In Node.js use process.on('SIGINT'), in Python catch KeyboardInterrupt, and in Go use signal.Notify with os.Interrupt.

Follow POSIX conventions: 0 for success, 1 for general errors, 2 for argument misuse, 77 for permission denied, 127 for not found, and 130 for SIGINT cancellation. Consistent exit codes let scripts and CI pipelines react to specific failure modes.