# The needs header

It must be the first thing in a file. A file without one has no permissions at all.

```sub
needs [
  read  [./src, ./tests],
  write [./src],
  run   ["npm test", "git add", "git commit"],
  net   [],
]
```

- Keys: `read`, `write`, `run`, `net`, `env`, `clock`, `random`.
- A missing key means none. `net []` says it out loud, and a reviewer sees that an empty bracket means no network.
- Paths are bare (`./src`) and stay inside the folder the script was started in unless the person grants more.
- Trailing commas and free whitespace inside brackets are fine.

:::tip
`sub explain` and the run prompt print the block back in plain words, so a person approves meaning, not syntax.
:::

## Reading it

| Line | Means |
| --- | --- |
| `read [./src, ./tests]` | read files and list folders under these two paths |
| `write [./src]` | create, change and delete files under `./src` |
| `run ["git commit"]` | start `git commit`, nothing else |
| `net []` | no network at all |

See [Permissions](/reference/permissions/) for every key and the subset rule.