/** Load environment variables from `.env` files (`.env`, `.env.{NODE_ENV|DENO_ENV}`, `.env.local`). */
export declare function loadEnv(options?: {
    cwd?: string;
    override?: boolean;
    debug?: boolean;
}): Promise<void>;
/** Check whether `.env` file loading is supported in the current runtime. */
export declare function supportsEnvFiles(): boolean;
/** Mark environment variables as loaded so subsequent calls to `loadEnv` are skipped. */
export declare function markEnvLoaded(): void;
/** Check whether environment variables have already been loaded from `.env` files. */
export declare function hasEnvLoaded(): boolean;
export declare function getEnvSource(key: string): {
    source: "env-file";
    file: string;
} | {
    source: "process";
} | {
    source: "unset";
};
export declare function __resetEnvLoaderForTests(): void;
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