Function isInteractive

pkg/selfupdate/selfupdate.go:636–642

isInteractive reports whether stdin is a terminal we can prompt on. It probes for an Fd() accessor (satisfied by *os.File and by common wrappers) rather than asserting a concrete *os.File, so a wrapped real terminal is still detected. A reader without a file descriptor (e.g. a bytes buffer in tests)

(stdin io.Reader)

// detected. A reader without a file descriptor (e.g. a bytes buffer in tests)
// or a non-terminal descriptor (pipe, redirect, CI) is non-interactive.
func isInteractive(stdin io.Reader) bool {
	f, ok := stdin.(interface{ Fd() uintptr })
	if !ok {
		return false
	}
	return isatty.IsTerminal(f.Fd()) || isatty.IsCygwinTerminal(f.Fd())
}

// selfUpdateEnv returns environ with every DOCKER_AGENT_SELF_UPDATE_* entry
// removed so the caller can append fresh markers without leaving duplicates.