How to fix TypeError: process.kill() invalid signal (signal name not recognized) in Node.js

// ✅ CORRECT
process.kill(pid, 'SIGTERM');
process.kill(pid, 'SIGINT');
process.kill(pid, 'SIGKILL');

// ❌ WRONG - numeric values
process.kill(pid, 15);  // TypeError

// ❌ WRONG - missing SIG prefix
process.kill(pid, 'TERM');  // TypeError

// ❌ WRONG - lowercase
process.kill(pid, 'sigterm');  // TypeError

// Platform-safe signal handling
const signal = process.platform === 'win32' ? 'SIGTERM' : 'SIGUSR2';

try {
  process.kill(pid, signal);
} catch (err) {
  if (err.code === 'ERR_UNKNOWN_SIGNAL') {
    console.error(`Signal ${signal} not supported on this platform`);
    // Fallback to SIGTERM
    process.kill(pid, 'SIGTERM');
  }
}

const VALID_SIGNALS = [
  'SIGABRT', 'SIGALRM', 'SIGBUS', 'SIGCHLD', 'SIGCONT', 'SIGFPE',
  'SIGHUP', 'SIGILL', 'SIGINT', 'SIGIO', 'SIGIOT', 'SIGKILL',
  'SIGPIPE', 'SIGPOLL', 'SIGPROF', 'SIGPWR', 'SIGQUIT', 'SIGSEGV',
  'SIGSTKFLT', 'SIGSTOP', 'SIGSYS', 'SIGTERM', 'SIGTRAP', 'SIGTSTP',
  'SIGTTIN', 'SIGTTOU', 'SIGUNUSED', 'SIGURG', 'SIGUSR1', 'SIGUSR2',
  'SIGVTALRM', 'SIGWINCH', 'SIGXCPU', 'SIGXFSZ', 'SIGBREAK'
];

function killProcess(pid, signal = 'SIGTERM') {
  if (!VALID_SIGNALS.includes(signal)) {
    throw new Error(`Invalid signal: ${signal}`);
  }

  return process.kill(pid, signal);
}

import os from 'os';

function isValidSignal(signal) {
  return signal in os.constants.signals;
}

if (isValidSignal('SIGTERM')) {
  process.kill(pid, 'SIGTERM');
}

function terminateProcess(pid, graceful = true) {
  const isWindows = process.platform === 'win32';

  if (graceful) {
    try {
      // Try graceful shutdown first
      if (isWindows) {
        // Windows doesn't fully support SIGTERM
        process.kill(pid, 'SIGINT');
      } else {
        process.kill(pid, 'SIGTERM');
      }

      // Give process time to clean up
      return new Promise((resolve) => {
        const timeout = setTimeout(() => {
          // Force kill if not terminated
          process.kill(pid, 'SIGKILL');
          resolve();
        }, 5000);

        // Clear timeout if process exits
        const interval = setInterval(() => {
          try {
            process.kill(pid, 0); // Check if process exists
          } catch {
            clearTimeout(timeout);
            clearInterval(interval);
            resolve();
          }
        }, 100);
      });
    } catch (err) {
      if (err.code !== 'ESRCH') { // Process doesn't exist
        throw err;
      }
    }
  } else {
    // Force kill
    process.kill(pid, 'SIGKILL');
  }
}