---
title: Getting started
description: Install lawbook, write a first lawbook.yaml, and run it in CI.
sidebar:
  order: 1
---

Lawbook needs Node.js 22.12 or newer.

```sh
npm install --global lawbook
```

## Write the first rules

From the directory you want to check, create a starter config:

```sh
lawbook init
```

This writes `lawbook.yaml` with two rules that pass in an empty directory, plus
commented examples of the other rule kinds. `init` never overwrites an existing
`lawbook.yaml`, `lawbook.yml`, or `lawbook.json`.

Open the file and describe your standards. Each rule has an `id`, an optional
`description`, and exactly one of the rule kinds from
[Configuration](/lawbook/configuration):

```yaml
version: 1
rules:
  - id: no-console
    description: Production code logs through the logger
    files: ["src/**/*.ts"]
    forbid: 'console\.(log|debug)\('
  - id: has-readme
    exists: README.md
```

## Run the check

```sh
lawbook check
```

```txt
FAIL no-console
  src/cli.ts:12: console.log("starting");
PASS has-readme

1 passed, 1 failed, 0 warned, 0 errored, 0 skipped
```

`check` exits `0` when every rule passes, `1` when any rule fails, and `2` when
it could not run at all, so it works as a CI step without extra scripting:

```yaml
- run: npx lawbook check
```

A config with `standard` rules needs the provider's CLI installed and signed
in on that runner, or `--no-llm` to report those rules as skipped; see
[Providers](/lawbook/providers).

On a pull request, check only the files the branch changed with
`--since origin/main`, and in a pre-commit hook pass the staged files with
`--files`; see [Commands](/lawbook/commands#checking-a-subset-of-files). Both keep a
`standard` rule's model requests to the files that moved.

Point it at another directory, or at a config kept elsewhere:

```sh
lawbook check path/to/project
lawbook check --config standards/lawbook.yaml
```

Pass `--format json` to feed the results to another tool, or `--only` to run a
subset of rules while you write them:

```sh
lawbook check --only no-console
```

A rule you are not yet sure of can run with `level: warn`. Its findings print
under `WARN` and the exit code ignores them, so CI stays green while you tune
the rule. Drop the `level` once it is right. On a codebase with many existing
findings, record them in a [baseline](/lawbook/baseline) so that only new ones fail.