export interface UpdateNotificationOptions {
    packageName: string;
    currentVersion: string;
    cacheRoot?: string;
    stdoutIsTTY?: boolean;
    env?: NodeJS.ProcessEnv;
    now?: () => number;
    ttlMs?: number;
    fetchText?: (url: string, maxBytes?: number, timeout?: number) => Promise<string>;
}
export declare function compareVersions(left: string, right: string): number;
export declare function getUpdateNotification(options: UpdateNotificationOptions): Promise<string | null>;