Remove files by name.

loop.js

const fs = require('fs');
const path = require('path');

const updateFile = filename => {
    const search = "postcss 'src/**/*.css' -d ./build --base src/";
    const shouldBe =
        "postcss 'src/**/*.css' -d ./build --base src/ --config '../../postcss.config.js'";

    fs.readFile(filename, 'utf8', (err, data) => {
        if (err) {
            return console.error(err);
        }
        const result = data.replace(search, shouldBe);

        fs.writeFile(filename, result, 'utf8', err => {
            if (err) return console.info(err);
        });
    });
};

const loop = (startPath, filter) => {
    if (!fs.existsSync(startPath)) {
        console.info('no dir ', startPath);

        return;
    }

    const files = fs.readdirSync(startPath);

    for (let i = 0; i < files.length; i++) {
        const filename = path.join(startPath, files[i]);
        const stat = fs.lstatSync(filename);

        if (stat.isDirectory()) {
            loop(filename, filter); // recurse
        } else if (filename.indexOf(filter) >= 0) {
            console.info(filename);
            updateFile(filename);
        }
    }
};

loop('./packages', 'package.json');