# How to Install Claude Code / Codex / Grok / Antigravity: A Beginner's Step-by-Step (Mac + Windows)

> Never touched a terminal? You can still follow this. Step-by-step install for four desktop AI command-line tools (Claude Code, Codex, Grok Build, Antigravity agy) on Mac and Windows: how to open the terminal, which line to paste, how to log in and use it, and the mistakes beginners hit most. Pick the one you already pay for. Tutorial.

Published: 2026-07-17
Locale: en
Tags: claude-code, codex, grok, antigravity, cli, tutorial, beginner, education

TL;DR: Paying for an AI tool but stuck on installing the desktop version? Hand-held guide: (1) how to open a terminal on Mac/Windows (including which of Windows' several terminals to pick and how to open PowerShell); (2) four tools (Claude Code / Codex / Grok / agy), each its own standalone section — pick the one you subscribe to and paste one line; (3) how to log in and drive it in plain language; (4) the traps beginners hit most (PATH, SmartScreen, execution policy, antivirus, confirming it actually installed). Install one, not all four.


> This one is for people who have **never touched a terminal and get nervous at a black window**. Whichever AI tool you pay for, jump to that section, paste along step by step, and you'll have it installed and running. **Pick one of the four (Claude Code / Codex / Grok / Antigravity) — you don't need all of them.** Mac and Windows are both covered, and I explain the different terminals too.

---

## Three words to get straight first (30 seconds)

- **Terminal**: a black (or white) window where you type commands to your computer. Everything below is just "paste one line into the terminal and press Enter."
- **CLI**: Command Line Interface. Operating a program by typing instead of clicking.
- **AI command-line assistant**: something like Claude Code, where you type a request in **plain language** (your own language is fine) in the terminal and it goes and writes code, edits files, or looks things up for you.

**You don't need to know how to program.** You only need to "copy one line, paste it into the terminal, press Enter."

---

## Step 0: Open a terminal first

### Mac

- **Built-in Terminal**: press `Command + Space` to open Spotlight, type `Terminal`, press Enter.
- **A nicer option (optional)**: you can install [iTerm2](https://iterm2.com/) (free, more features), but **the built-in one is more than enough** — beginners, just use the built-in.

### Windows (relax, one step at a time)

Windows has several "terminals" and the names look alike, so they're easy to mix up. Read this table once, know what each is and when to use which — **you don't need to memorize it all**:

| Terminal | What it is | When this guide uses it |
|---|---|---|
| **PowerShell** | Windows' built-in blue (or black) window | Installing Claude Code, Codex, agy all use this |
| **Windows Terminal** | A newer, prettier shell that can also open PowerShell inside it | Use it if you have it; no difference if you don't |
| **Git Bash** | A window that lets Windows run Mac/Linux commands (installed separately) | None of the four tools here need it (advanced use only) |
| **Command Prompt (cmd)** | A very old black window | Not used here; don't pick it |

**Beginners only need one sentence: on Windows, open "PowerShell" for everything here.** (There are also advanced terminals like Git Bash and WSL — ignore them for now.)

#### How to open PowerShell (follow along, don't skip a step)

1. Press the **Start key** on your keyboard (the one with the Windows logo), or click the Start button at the bottom-left of the screen.
2. **Just type on the keyboard**: `powershell` (no need to click any box first — typing starts the search).
3. At the top you'll see the "**Windows PowerShell**" icon (a blue icon with a `>_` symbol). **Click it once.**
4. A blue (or black) window opens with a blinking cursor → **done, this is the "terminal."** Every command below gets pasted into this window and run with Enter.

> **About "Administrator"**: most steps here **do not** need admin rights, just open it normally. If some step really asks for admin, go back to step 3 and instead **right-click the "Windows PowerShell" icon → "Run as administrator."**
>
> **How to paste a command into PowerShell**: copy the command from the web page, move your mouse into the PowerShell window, and **right-click once** to paste (or press `Ctrl + V`), then press Enter.

---

## Before you start

- **Safety**: these install commands "download and run something from the internet directly," so **only copy commands from the official URLs listed in this article**. Don't copy "install commands" from search ads, forums, or random posts — those can be fake.
- **Too old a system may not install**: roughly you need macOS 13+ / Windows 10+; a very old machine may fail partway.

---

## Install Claude Code (Anthropic)

Claude Code is Anthropic's AI command-line assistant. There are **two ways** to install it — beginners, use the first.

### Method A: official installer (recommended, nothing else to install first)

This way **does not need Node.js first** — it sets everything up itself and even auto-updates.

**Mac / Linux** — open the terminal, paste this line and press Enter:

```bash
curl -fsSL https://claude.ai/install.sh | bash
```

**Windows (step by step, don't skip):**

1. Open that blue window with "How to open PowerShell" above.
2. Copy the whole line below, move your mouse into the PowerShell window, **right-click** to paste (or `Ctrl + V`), and press **Enter**:

```powershell
irm https://claude.ai/install.ps1 | iex
```

3. It starts downloading and installing on its own; text scrolls by. **You don't need to do anything — just wait until it finishes and a fresh cursor is blinking** (about 1–2 minutes; slower is fine).

After it's installed (same on Mac and Windows): **close this terminal window entirely and open a new one** (important, or it won't recognize the command you just installed), then in the new window type:

```bash
claude
```

The first time, it pops open your browser to **log in to the Claude account you already pay for** — click through and you're done.

### Method B: install with npm (advanced / if you already have Node.js)

If you plan to code later, or already have Node.js, you can use this. **Needs Node.js version 22 or higher.**

First check whether you have Node (type in the terminal):

```bash
node --version
```

If not, go to [nodejs.org](https://nodejs.org/), download the "LTS" version and install it. Then:

```bash
npm install -g @anthropic-ai/claude-code
```

> **Do not** put `sudo` in front. If you get a permission error, the right fix is to switch to nvm (which installs Node in your own folder), not to force it as administrator.

### How to use it once installed (your first run)

1. First make a **clean practice folder** and go into it (don't run it straight in your Desktop, Documents, or a folder with private files):
   - Mac: `mkdir -p ~/Desktop/ai-practice && cd ~/Desktop/ai-practice`
   - Windows: `mkdir $HOME\Desktop\ai-practice ; cd $HOME\Desktop\ai-practice`
2. Type `claude` to go in.
3. Just type what you want in **plain language**, for example:
   - "Build me a simple web page in this folder, with the title 'My First Page'"
   - "What is this folder for? Explain it to me in plain words"
4. It proposes a plan and edits files, and **it asks before doing anything important — read it and then say yes; don't just keep hitting 'always allow.'**
5. Handy: type `/help` for commands, `/clear` to start over, `/exit` to leave.

**Installed, and now you can use it.** If Claude is the only tool you pay for, you're done here — no need to read the rest.

---

## Install Codex CLI (OpenAI)

Codex is OpenAI's AI command-line assistant, strong at engineering work.

**Mac / Linux (recommended, simplest)** — paste this line and press Enter:

```bash
curl -fsSL https://chatgpt.com/codex/install.sh | sh
```

**Mac (only if you already have Homebrew):**

```bash
brew install --cask codex
```

> If you've never installed Homebrew, this line shows `brew: command not found` — beginners, just use the official script above and don't bother with Homebrew.

**Windows** — open PowerShell (see above), paste this whole line and press Enter:

```powershell
powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"
```

**With npm (cross-platform, install Node.js first — use the latest LTS):**

```bash
npm install -g @openai/codex
```

Close the terminal, reopen it, and type:

```bash
codex
```

The first time it asks you to **log in with the ChatGPT account you already pay for** (one click in the browser).

- **Tip**: run Codex in a **git folder** so changes are easier to track and roll back — but note git only restores files you've already committed, it isn't a magic undo, so back up important data separately first.
- **How to use it**: go into your folder, type `codex`, and just tell it what to do in plain language (e.g. "build a simple web page in this folder"); type `/` for commands, `/exit` to leave.

---

## Install Grok CLI (xAI, called Grok Build)

Grok Build is from xAI (Musk's AI company), running on Grok 4.5 underneath.

**Mac / Linux** — open the terminal, paste this line and press Enter:

```bash
curl -fsSL https://x.ai/cli/install.sh | bash
```

**Windows** — open PowerShell (see above), paste this line and press Enter:

```powershell
irm https://x.ai/cli/install.ps1 | iex
```

Close the terminal, reopen it, go to your folder and type:

```bash
grok
```

The first time it opens your browser to log in (use the xAI account you pay for).

- **How to use it**: go into your folder, type `grok`, and tell it what to do in plain language; type `/` for commands, `/exit` to leave.

---

## Install agy (Google Antigravity CLI)

`agy` is Google's AI command-line assistant, the successor to the old "Gemini CLI" (which was retired in 2026). It's a **single executable — no Node or Python needed**.

**Mac / Linux:**

```bash
curl -fsSL https://antigravity.google/cli/install.sh | bash
```

**Windows** — open PowerShell (see above), paste this line and press Enter:

```powershell
irm https://antigravity.google/cli/install.ps1 | iex
```

Close the terminal, reopen it, and type:

```bash
agy
```

The first run **signs you in with your Google account automatically** — just click through. If you used Gemini CLI before, it moves your old settings over for you.

- New conversation: `agy`; continue the last one: `agy -c`.
- **How to use it**: go into your folder, type `agy`, and tell it what to do in plain language.

---

## Where beginners get stuck (read this)

- **"command not found" after pasting**: first close the terminal entirely and open a new one (new commands only register after a restart). Still not found? Usually PATH isn't set: on Mac type `command -v claude`, on Windows type `Get-Command claude` (swap in the other tool's name) to see if it's found; add the path the installer showed you to PATH and reopen.
- **How do I confirm it installed?**: type `claude --version` (or `codex` / `grok` / `agy` for whichever you installed). **A version number means it's installed**; only red error text means it didn't — don't assume it worked.
- **Windows shows the blue "Windows protected your PC" (SmartScreen)**: click "More info" → "Run anyway." (Only do this when installing from the official URLs in this article.)
- **Windows says "cannot load script / execution policy"**: paste `Set-ExecutionPolicy -Scope CurrentUser RemoteSigned` in PowerShell, press Enter, type `Y`, then run the install command again.
- **Mac says "install command line tools" or "cannot verify developer"**: for the first, click "Install"; for the second, go to "System Settings → Privacy & Security" and click "Open Anyway."
- **A work computer / antivirus blocks the download**: **do not** turn off antivirus; hand it to your company's IT, or install on your own machine.
- **Told to add sudo?**: only Mac/Linux global npm installs hit permission errors — **do not** force it with `sudo` (use nvm as the docs recommend); Windows has no sudo.
- **The login window didn't pop up**: copy the URL the terminal shows and paste it into your browser; and make sure the browser is signed in to the account you actually pay for.

---

*This will probably be updated (these tools version fast). If a command doesn't run, defer to each official page: [Claude Code](https://code.claude.com/docs/en/setup), [Codex](https://developers.openai.com/codex/cli), [Grok Build](https://x.ai/cli), [Antigravity](https://antigravity.google/docs/cli-install).*