restart_cups

Restarts the CUPS (Common Unix Printing System) print service on macOS or the Print Spooler on Windows. Use when printers are not discoverable, queue management is broken, or after adding/removing printers.

Metadata

Name

restart_cups

Updated

3 weeks ago

Source

GitHub source

Risk

Medium

Requires consent

true

Affected scope

system

Code

/**
 * mcp/skills/restartCups.ts — restart_cups skill
 *
 * Restarts the CUPS (Common Unix Printing System) print service on macOS
 * or the Print Spooler on Windows.  Use when printers are not discoverable,
 * queue management is broken, or after adding/removing printers.
 *
 * Platform strategy
 * -----------------
 * darwin  `lpstat -r` to check status; `sudo launchctl stop/start org.cups.cupsd`
 * win32   PowerShell Get-Service Spooler; Restart-Service -Name Spooler -Force
 *
 * Smoke test
 *   npx tsx -r dotenv/config mcp/skills/restartCups.ts
 */

import * as os       from "os";
import { exec }      from "child_process";
import { promisify } from "util";
import { z }         from "zod";

const execAsync = promisify(exec);

// -- Meta ---------------------------------------------------------------------

export const meta = {
  name: "restart_cups",
  description:
    "Restarts the CUPS (Common Unix Printing System) print service on macOS " +
    "or the Print Spooler on Windows. " +
    "Use when printers are not discoverable, queue management is broken, " +
    "or after adding/removing printers.",
  riskLevel:       "medium",
  destructive:     true,
  requiresConsent: true,
  supportsDryRun:  true,
  affectedScope:   ["system"],
  auditRequired:   true,
  escalationHint:  {
    darwin: "sudo launchctl kickstart -k system/org.cups.cupsd",
    win32:  "Restart-Service Spooler -Force  # run from elevated PowerShell",
  },
  schema: {
    dryRun: z
      .boolean()
      .optional()
      .describe("If true, check service status without restarting. Default: true"),
  },
} as const;

// -- Types --------------------------------------------------------------------

interface RestartCupsResult {
  wasRunning:  boolean;
  restarted:   boolean;
  isRunning:   boolean;
  dryRun:      boolean;
  platform:    string;
  message:     string;
}

// -- PowerShell helper --------------------------------------------------------

async function runPS(script: string): Promise<string> {
  const encoded = Buffer.from(script, "utf16le").toString("base64");
  const { stdout } = await execAsync(
    `powershell.exe -NoProfile -NonInteractive -EncodedCommand ${encoded}`,
    { maxBuffer: 10 * 1024 * 1024 },
  );
  return stdout.trim();
}

// -- darwin implementation ----------------------------------------------------

async function restartCupsDarwin(dryRun: boolean): Promise<RestartCupsResult> {
  let wasRunning = false;
  try {
    const { stdout } = await execAsync("lpstat -r");
    wasRunning = stdout.toLowerCase().includes("scheduler is running");
  } catch {
    wasRunning = false;
  }

let restarted = false;
  if (!dryRun) {
    try {
      await execAsync("sudo launchctl kickstart -k system/org.cups.cupsd");
      restarted = true;
    } catch {
      restarted = false;
    }
  }

let isRunning = wasRunning;
  if (!dryRun) {
    await new Promise((resolve) => setTimeout(resolve, 1000));
    try {
      const { stdout } = await execAsync("lpstat -r");
      isRunning = stdout.toLowerCase().includes("scheduler is running");
    } catch {
      isRunning = false;
    }
  }

const message = dryRun
    ? `CUPS scheduler is currently ${wasRunning ? "running" : "stopped"}. Run with dryRun=false to restart.`
    : restarted
      ? `CUPS restarted successfully. Scheduler is now ${isRunning ? "running" : "stopped"}.`
      : "Failed to restart CUPS. You may need to run with sudo privileges.";

return { wasRunning, restarted, isRunning, dryRun, platform: "darwin", message };
}

// -- win32 implementation -----------------------------------------------------

async function restartCupsWin32(dryRun: boolean): Promise<RestartCupsResult> {
  let wasRunning = false;
  try {
    const raw = await runPS(
      `Get-Service Spooler | Select-Object -ExpandProperty Status`,
    );
    wasRunning = raw.trim().toLowerCase() === "running";
  } catch {
    wasRunning = false;
  }

let restarted = false;
  if (!dryRun) {
    try {
      await runPS("Restart-Service -Name Spooler -Force");
      restarted = true;
    } catch {
      restarted = false;
    }
  }

let isRunning = wasRunning;
  if (!dryRun) {
    await new Promise((resolve) => setTimeout(resolve, 1000));
    try {
      const raw = await runPS(
        `Get-Service Spooler | Select-Object -ExpandProperty Status`,
      );
      isRunning = raw.trim().toLowerCase() === "running";
    } catch {
      isRunning = false;
    }
  }

const message = dryRun
    ? `Print Spooler is currently ${wasRunning ? "running" : "stopped"}. Run with dryRun=false to restart.`
    : restarted
      ? `Print Spooler restarted successfully. Service is now ${isRunning ? "running" : "stopped"}.`
      : "Failed to restart Print Spooler. Ensure you have administrator privileges.";

return { wasRunning, restarted, isRunning, dryRun, platform: "win32", message };
}

// -- Exported run function ----------------------------------------------------

export async function run({
  dryRun = true,
}: {
  dryRun?: boolean;
} = {}) {
  const platform = os.platform();
  return platform === "win32"
    ? restartCupsWin32(dryRun)
    : restartCupsDarwin(dryRun);
}

// -- Smoke test ---------------------------------------------------------------

if (false) {
  run({})
    .then(r => console.log(JSON.stringify(r, null, 2)))
    .catch((err: Error) => { console.error(err.message); process.exit(1); });
}
``