# Getting started

639 Shell is a cloud for agents: Linux machines that you and your AI agents create, run and put
online, from a terminal, over MCP or through the API. A machine is ready in seconds (see Benchmarks), sleeps
when nobody is using it and wakes right where it left off. Compute is billed per second while a
machine is awake; its disk is billed all the time.

## Sign up

639 Shell is invite-only for now.

1. Run `ssh shell.639cloud.com` and enter your email. Not invited yet? That records a request, and
   we email you when you're approved, with an **approval code**.
2. Run `ssh shell.639cloud.com` again with the same email. You get a sign-in link and a QR code.
   No SSH key yet? It tells you how to make one (`ssh-keygen -t ed25519`).
3. Open the link (or scan it). Check the key fingerprint it shows is the terminal in front of you.
4. **Continue with Google**, or **use your approval code** (from the approval email).
5. The page shows a short code. Type it into your terminal: that confirms it's really you at that
   terminal. Never give this code to anyone.
6. Fill in your profile and accept the terms. Back in the terminal, the app opens by itself.
   Next time, `ssh shell.639cloud.com` just logs in.

**Another computer:** do the same from it, signing in the same way (the same Google account, or a
new approval code from us), and type the page's code in that computer's terminal. Then both keys
see the same machines.

**Questions or problems?** **Send feedback** in the app, or email micah@639cloud.com.

## Your first machine

```sh
ssh -t shell.639cloud.com
```

Choose **New machine**, pick a size and an image, then **Open shell**. You are root. Type `exit`
to come back to the app.

Or skip the app entirely:

```sh
ssh -t ubuntu-1@shell.639cloud.com          # a root shell on ubuntu-1 (wakes it)
ssh ubuntu-1@shell.639cloud.com 'uname -a'  # one command, output streamed
```

## Getting around the app

Arrows or `j`/`k` move, Enter opens, Esc or `q` goes back. Press `:` for the command line and
`/` to search. These docs are under **Docs**; press `o` there for a link to read them in your
browser.

## What the login name does

| Login | Opens |
|---|---|
| a machine name (`ubuntu-1@`) | that machine: a root shell, a command, or scp/sftp |
| `mcp@` | the MCP server for AI agents |
| `vpc@`, `ip@`, `keys@` | one-shot commands for private networks, public IPs and API keys |
| `export@` | your machines as an SSH config or JSON |
| `docs@` | these docs as Markdown |
| `legal@` | the terms of service, privacy policy and abuse contact |
| anything else | the app |

The app and interactive shells need a terminal: use `ssh -t`.

## Save these docs

```sh
ssh docs@shell.639cloud.com                          # list the pages
ssh docs@shell.639cloud.com machines > machines.md   # save one
ssh docs@shell.639cloud.com all > 639-shell-docs.md  # all of them, in one file
```