Function getProcessOnPort

packages/cli/src/server/portUtils.ts:191–202

* Get the PID of the process listening on a port (macOS/Linux only). * Returns null on Windows or if detection fails.

(port: number)

 * Returns null on Windows or if detection fails.
 */
async function getProcessOnPort(port: number): Promise<string | null> {
  if (process.platform === "win32") return null;
  try {
    const { stdout } = await execFileAsync("lsof", [`-ti:${port}`, "-sTCP:LISTEN"], {
      timeout: 2000,
    });
    const pid = stdout.trim().split("\n")[0]?.trim();
    return pid || null;
  } catch {
    return null;
  }
}

// ── Server discovery ───────────────────────────────────────────────────────