How to use the graceful-fs.readdir function in graceful-fs

function installManyTop_ (what, where, context, cb) {
  var nm = path.resolve(where, "node_modules")
    , names = context.explicit
            ? what.map(function (w) { return w.split(/@/).shift() })
            : []

  fs.readdir(nm, function (er, pkgs) {
    if (er) return installMany(what, where, context, cb)
    pkgs = pkgs.filter(function (p) {
      return !p.match(/^[\._-]/)
    })
    asyncMap(pkgs.map(function (p) {
      return path.resolve(nm, p, "package.json")
    }), function (jsonfile, cb) {
      readJson(jsonfile, log.warn, function (er, data) {
        if (er && er.code !== "ENOENT" && er.code !== "ENOTDIR") return cb(er)
        if (er) return cb(null, [])
        return cb(null, [[data.name, data.version]])
      })
    }, function (er, packages) {
      // if there's nothing in node_modules, then don't freak out.
      if (er) packages = []
      // add all the existing packages to the family list.

self._watchDir(dir, function(event, dirpath) {
      var relDir = cwd === dir ? '.' : path.relative(cwd, dir);
      relDir = relDir || '';

      fs.readdir(dirpath, function(err, current) {
        if (err) { return self.emit('error', err); }
        if (!current) { return; }

        try {
          // append path.sep to directories so they match previous.
          current = current.map(function(curPath) {
            if (fs.existsSync(path.join(dir, curPath)) && fs.lstatSync(path.join(dir, curPath)).isDirectory()) {
              return curPath + path.sep;
            } else {
              return curPath;
            }
          });
        } catch (err) {
          // race condition-- sometimes the file no longer exists
        }

function readdir(name) {
    resolveLeft++
    fs.readdir(name, function (er, inst) {
      if (er) return resolveLeft--

      // don't even mess with non-package looking things
      inst = inst.filter(function (p) {
        if (!p.match(/^[@\._-]/)) return true
        // scoped packages
        readdir(path.join(name, p))
      })

      asyncMap(inst, function (pkg, cb) {
        var jsonPath = path.resolve(name, pkg, 'package.json')
        log.verbose('targetResolver', 'reading package data from', jsonPath)
        readJson(jsonPath, log.info, function (er, d) {
          if (er && er.code !== "ENOENT" && er.code !== "ENOTDIR") return cb(er)
          // error means it's not a package, most likely.
          if (er) return cb(null, [])

function copyDir (src, dest, opts, cb) {
  fs.readdir(src, (err, items) => {
    if (err) return cb(err)
    return copyDirItems(items, src, dest, opts, cb)
  })
}

DirectoryWatcher.prototype.doInitialScan = function doInitialScan() {
	fs.readdir(this.path, function(err, items) {
		if(err) {
			this.parentWatcher = watcherManager.watchFile(this.path + "#directory", this.options, 1);
			this.parentWatcher.on("change", function(mtime, type) {
				if(this.watchers[withoutCase(this.path)]) {
					this.watchers[withoutCase(this.path)].forEach(function(w) {
						w.emit("change", this.path, mtime, type);
					}, this);
				}
			}.bind(this));
			this.initialScan = false;
			return;
		}
		async.forEach(items, function(item, callback) {
			var itemPath = path.join(this.path, item);
			fs.stat(itemPath, function(err2, stat) {
				if(!this.initialScan) return;

function updateFileCountProbe() {
  fs.readdir(PM2_ROOT_PATH + "/logs", function (err, files) {
      if (err) {
        console.error(err.stack || err);
        return metrics.totalcount.set(0);
      }

      return  metrics.totalcount.set(files.length);
  });
}
updateFileCountProbe();

function copyDir (dir) {
    fs.readdir(dir, function (err, items) {
      if (err) return onError(err)
      items.forEach(function (item) {
        startCopy(path.join(dir, item))
      })
      return doneOne()
    })
  }

return wrapPromise(function(resolve, reject) {
    fs.readdir(filePath, function(err, filePaths) {
      if (err) {
        reject(err);
        return;
      }
      resolve(filePaths);
    });
  });
};

var f = ff(this, function () {
			fs.readdir(addonPath, f());
			this.startupPlugins(f.waitPlain());
		}, function (files) {
			files.forEach(bind(this, installAddon, projectPath));

function list (gyp, args, callback) {
  var devDir = gyp.devDir
  log.verbose('list', 'using node-gyp dir:', devDir)

  fs.readdir(devDir, onreaddir)

  function onreaddir (err, versions) {
    if (err && err.code !== 'ENOENT') {
      return callback(err)
    }

    if (Array.isArray(versions)) {
      versions = versions.filter(function (v) { return v !== 'current' })
    } else {
      versions = []
    }
    callback(null, versions)
  }
}