Go CLI Design

A good CLI is a well-behaved Unix citizen: flags before magic, stdout for data, stderr for diagnostics, exit codes that scripts can trust, and Ctrl+C that actually stops it.

1. Structure: Testable main

func main() {
    ctx, stop := signal.NotifyContext(context.Background(),
        os.Interrupt, syscall.SIGTERM)
    defer stop()

    if err := run(ctx, os.Args[1:], os.Stdin, os.Stdout, os.Stderr); err != nil {
        fmt.Fprintln(os.Stderr, "error:", err)
        os.Exit(1)
    }
}