Unix Philosophy
- Do one thing and do it well.
- Accept input from stdin where applicable; write output to stdout; errors to stderr.
- Silent on success unless
-v / --verbose is passed.
- Exit
0 on success; non-zero on failure. Use distinct exit codes for distinct failure modes.
Interface
--help and --version are mandatory.- Support
--dry-run for any destructive or irreversible operation.
- No interactive prompts in non-TTY environments (detect with
isatty).
- Prefer long flags (
--output) with short aliases (-o).
- Use a proper CLI framework:
cobra (Go), CLI11 (C++), picocli (Java).
Output
- Support
--output json (or similar) for machine-readable output; human-readable is the default.
- Never mix diagnostic or progress output with data output on stdout.
Error Reporting
- Errors go to
stderr with enough context to diagnose without consulting logs.
- Refer users to
--debug or --verbose for more detail.