/** Probe whether a PID is alive. Signal 0 performs the permission/existence check
 *  without actually delivering a signal; a throw (ESRCH/EPERM-as-dead handled by caller)
 *  means the process is not addressable as a live, signalable target. */
export declare function isProcessAlive(pid: number): boolean;
export interface AcquireResult {
    acquired: boolean;
    /** Set when acquired === true: whether a stale/corrupt lock was reclaimed. */
    stale?: boolean;
    /** Set when acquired === false: the PID currently holding the lock. */
    holderPid?: number;
}
/**
 * Attempt to take a PID-file singleton lock.
 * - File missing                       → write own pid, { acquired: true, stale: false }
 * - File holds a live, valid pid       → { acquired: false, holderPid }
 * - File holds a dead/corrupt pid      → overwrite with own pid, { acquired: true, stale: true }
 *
 * This function never exits the process or logs — the caller decides how to react to a
 * conflict (typically: log a message and process.exit(1)).
 */
export declare function tryAcquireSingletonLock(pidFile: string): AcquireResult;
/** Release the lock iff it is still owned by the current process. Best-effort; swallows errors. */
export declare function releaseSingletonLock(pidFile: string): void;