# Linter

Woodpecker automatically lints your workflow files for errors, deprecations and bad habits. Errors and warnings are shown in the UI for any pipelines.

![errors and warnings in UI](./linter-warnings-errors.png)

## Running the linter from CLI

You can run the linter also manually from the CLI:

```shell
woodpecker-cli lint <workflow files>
```

## Bad habit warnings

Woodpecker warns you if your configuration contains some bad habits.

### Event filter for all steps

All your items in `when` blocks should have an `event` filter, so no step runs on all events. This is recommended because if new events are added, your steps probably shouldn't run on those as well.

Examples of an **incorrect** config for this rule:

```yaml
when:
  - branch: main
  - event: tag
```

This will trigger the warning because the first item (`branch: main`) does not filter with an event.

```yaml
steps:
  - name: test
    when:
      branch: main

  - name: deploy
    when:
      event: tag
```

Examples of a **correct** config for this rule:

```yaml
when:
  - branch: main
    event: push
  - event: tag
```

```yaml
steps:
  - name: test
    when:
      event: [tag, push]

  - name: deploy
    when:
      - event: tag
```