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

const filepath = path.join(process.cwd(), "hello.txt");

fs.readFile(filepath, "utf8", (err, contents) => {
  if (err) {
    return console.log(err);
  }
  console.log("File Contents:", contents);
  const upperContents = contents.toUpperCase();

  fs.writeFileSync(filepath, upperContents);
  console.log("File updated.");
});