+++
title = "Shell"
description = "The firmware's own commands, typed on the device: look at its state, the SD card, the radio and the network with no PC and no cable."
weight = 9
[extra]
tag = "Shell"
+++

The firmware has a set of **commands**, made for working on it from a PC. The Shell runs them **on the device itself**: no computer, no cable, no Wi-Fi. It is the tool for the day something is wrong and you are nowhere near a desk.

It can do real damage: `rm` deletes, `reboot` restarts, `debug on` opens the device to the network. It is the same trust as holding the device, and nothing more.

## Using it

Type a command and press <kbd>Enter</kbd>. `help` lists them all; the [command reference](/dev/debug/commands/) says what each does. A few to start with:

| Command | Shows |
|---|---|
| `info` | The firmware's version, uptime, memory, Wi-Fi, the SD card and both firmware slots |
| `wifi status` | The network, the address, and where the DNS and time servers came from |
| `ls /notes` | A folder of the SD card, with sizes and dates |
| `crash` | The last crash, if there was one |
| `update check` | Whether a newer release exists |
| `lora status` | What the radio is set to and what it has heard |

- <kbd>Tab</kbd> **completes** the command's name. If several fit, it lists them.
- <kbd>Fn</kbd> with up and down brings back **lines you typed before**.
- <kbd>Alt</kbd> with up and down **scrolls back** through what was printed.
- `clear` empties the screen, and `quit` (or Back) leaves.

## What you see

The Shell shows **everything the firmware prints** while it is open: the answers to your commands, and whatever the rest of the system says meanwhile (IRC connecting, a packet received). On a ten-line screen that can be a lot.

<kbd>Ctrl</kbd> + <kbd>b</kbd> hides the background: then only what is printed in the **ten seconds after each of your commands** is kept, and `mine` shows in the corner. It is ten seconds and not "the answer" because some commands answer a moment later, from another part of the firmware, and nothing marks their lines as theirs.

## Deleting asks first

`rm <path>` asks before it deletes, here where a slip of the finger is one key away. `rm -f <path>` does not ask.

## Screenshots

```
screenshot        the screen, now
screenshot 5      the screen in 5 seconds: time to go to another App
```

The picture is saved as a PNG in `/screenshots` on the SD card, named by date and time, and a Toast says so once it is written (so the Toast is never in the picture). From the Shell, "now" is always a picture of the Shell: use the pause to get to the screen you want. The [Storage App](/guide/storage/) shows the files; to look at them, take the card to a computer.

## What it costs

Nothing while it is closed. Open, about 7 KB of memory, given back when you leave: with IRC connected and a Gemini page open, that can be the difference (see [the memory limit](/howto/not-enough-memory/)).

## The keys, as the device lists them

What <kbd>Fn</kbd> + <kbd>h</kbd> shows on this screen. This table is generated from the firmware's own lists, so it is always the current one.

{{ keys(scopes=["shell"]) }}