learnyounode/exercises/my_first_io/problem.md

Learn You The Node.js For Much Win! An intro to Node.js via a set of self-guided workshops.

Write a program that uses a single **synchronous** filesystem operation to read a file and print the number of newlines (\n) it contains to the console (stdout), similar to running `cat file | wc -l`.

The full path to the file to read will be provided as the first command-line argument (i.e., process.argv[2]). You do not need to make your own test file.

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## HINTS

To perform a filesystem operation you are going to need the `fs` module from the Node core library. To load this kind of module, or any other "global" module, use the following incantation:

```js
const fs = require('fs')
```

Now you have the full `fs` module available in a variable named `fs`.

All synchronous (or blocking) filesystem methods in the `fs` module end with 'Sync'. To read a file, you'll need to use `fs.readFileSync('/path/to/file')`. This method will *return* a `Buffer` object containing the complete contents of the file.

Documentation on the `fs` module can be found by pointing your browser here:
  {rootdir:/docs-nodejs/fs.html}

`Buffer` objects are Node's way of efficiently representing arbitrary arrays of data, whether it be ascii, binary or some other format. `Buffer` objects can be converted to strings by simply calling the `toString()` method on them. e.g. `const str = buf.toString()`.

Documentation on `Buffer`s can be found by pointing your browser here:
  {rootdir:/docs-nodejs/buffer.html}

If you're looking for an easy way to count the number of newlines in a string, recall that a JavaScript `String` can be `.split()` into an array of substrings and that '\n' can be used as a delimiter. Note that the test file does not have a newline character ('\n') at the end of the last line, so using this method you'll end up with an array that has one more element than the number of newlines.