Folders, files and an editor (Windows, Mac and Linux)

You downloaded the letter from the Finanças (the tax office) yesterday. Where is it? Your file explorer says "Downloads" (or a translated name, such as "Transferências" on a Portuguese system). The terminal, and any coding agent, says something else:

• Windows: C:\Users\Graca\Downloads\carta_financas.pdf
• Mac: /Users/graca/Downloads/carta_financas.pdf
• Linux: /home/graca/Transferências/carta_financas.pdf (on Linux, folder names may come translated)

It is the same file written as an address. In this lesson you learn to read these addresses, to see what the computer hides and to open a whole folder in an editor.

The path is the address

A path is read from left to right, like an address in reverse: disk, folder, subfolder, file. On Windows folders are separated with \; on Mac and Linux, with /.

There are two kinds of path:

• Absolute: starts at the beginning of the disk (C:\ or /). It works from anywhere.
• Relative: starts from the folder you are in. If you are inside experiencias, the path index.html is enough to refer to the file that is there.

The sign ~ means "my personal folder". ~/experiencias is the experiencias folder inside your personal folder. Agents use this a lot.

The extension tells the type

The letters after the last dot are the extension: .pdf (document), .docx (Word), .txt (plain text), .html (web page), .py (Python), .js (JavaScript), .md (text with simple formatting), .json (data).

Windows hides extensions by default. For someone who is going to work with code, that is bad: you cannot tell index.html from index.html.txt. And it is dangerous: factura.pdf.exe shows up as factura.pdf.

This is how it looks on 6 October 2026; your screen may differ.

• Windows 11: in File Explorer, View > Show and switch on file name extensions ("File name extensions").
• Windows 10: the View tab, the "Show/hide" group, tick the box for file name extensions.

Hidden files

On Mac and Linux, a file whose name starts with a dot is hidden. You will often meet two of them in this course:

• .env: holds secrets, such as access keys. It is never shared.
• .gitignore: lists what Git should not keep (lesson 1/05).

To see them:

• Mac (Finder): Cmd + Shift + . (dot) switches them on and off.
• Linux (file manager): usually Ctrl + H.
• Windows: names with a dot appear normally; other hidden things, such as the .git folder, only with View > Show > Hidden items.
• In the terminal: ls -a on Mac and Linux; dir -Force in PowerShell.

An editor: VS Code

Word is no good for code: it puts hidden formatting into the file. You need a plain text editor. Notepad would do, but VS Code (free, from Microsoft) shows the whole folder on the left, colours the code and has a terminal inside.

1. Go to the Visual Studio Code website, download the version for your system and install it like any program.
2. Open VS Code and use File > Open Folder…. Choose the experiencias folder.
3. On the left appears the Explorer, with the files of the folder.
4. For the terminal inside the editor: View > Terminal, or Ctrl + ` (the backtick key). It opens already inside the folder.

Official guide: What is a VS Code workspace?

Windows: WSL in five lines

1. Many programming tools were born on Linux and Mac, so many guides assume the commands of those systems.
2. WSL (Windows Subsystem for Linux) puts a real Linux inside Windows, without deleting anything.
3. It needs Windows 10 version 2004 or later, or Windows 11. Open PowerShell as administrator (right-click, "Run as administrator") and type wsl --install.
4. Restart the computer. Ubuntu is installed by default.
5. The first time you open it, you create a user name and a password just for Linux.

Source: Install WSL.

You can work without WSL. Claude Code and Codex have installers for Windows (lesson 1/02), and in this course every command has the Windows version beside it. WSL is handy when a guide only has Linux commands.