gulpfile.js

function isMasterRunning() {
    var pidFilePath = path.join(__dirname, 'ds.pid');
    var strpid;
    var isRunning;
    if (fs.existsSync(pidFilePath)) {
        strpid = fs.readFileSync(pidFilePath, 'utf-8');
        isRunning = require('is-running')(parseInt(strpid, 10));
    }
    if (isRunning) {
        return strpid;
    }
    return false;
}

gulp.task('start', ['build-and-clean'], function () {
    var strpid = isMasterRunning();
    if (strpid) {
        console.log('pm master is running. sending USR1 signal...');
        exec('kill -s USR1 ' + strpid);
    } else {
        console.log('pm master is not running. spawning one...');
        spawn(process.execPath, [path.join(__dirname, 'master.js')], {
            cwd: __dirname,
            env: assign({}, process.env, {
                NODE_ENV: 'production'
            }),
            silent: true,
            detached: true,
            stdio: ['ignore', 'ignore', 'ignore']
        })
            .unref();
    }
});
gulp.task('stop', function () {
    var strpid = isMasterRunning();
    if (strpid) {
        console.log('pm master is running. terminating...');
        exec('kill -s TERM ' + strpid);
    } else {
        console.log('pm master is not running. exiting...');
    }
});