> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vms.verolabs.co/llms.txt
> Use this file to discover all available pages before exploring further.

# Probe: file_check

> Check file existence, size, and age

<Info>
  This probe is currently at the experimental stage.
</Info>

## Description

The `file_check` probe checks a file on the filesystem: existence, size, and age (modification time).

## Config fields

| Field           | Type     | Required | Default | Description                                                             |
| --------------- | -------- | -------- | ------- | ----------------------------------------------------------------------- |
| `type`          | `string` | Yes      | —       | Must be `"file_check"`                                                  |
| `filePath`      | `string` | Yes      | —       | File path to check                                                      |
| `mustExist`     | `bool`   | No       | `true`  | `true`: file must exist → absent = `down`. `false`: absent file is `up` |
| `minSizeBytes`  | `int64`  | No       | —       | Minimum file size (bytes)                                               |
| `maxSizeBytes`  | `int64`  | No       | —       | Maximum file size (bytes)                                               |
| `maxAgeSeconds` | `int64`  | No       | —       | Maximum file age (seconds since last modification)                      |

## Metrics

| Metric                  | Type   | Description    |
| ----------------------- | ------ | -------------- |
| `vms.file_check.status` | status | `up` or `down` |

## Example config

```json theme={null}
{
  "type": "file_check",
  "filePath": "/var/log/app/app.log",
  "mustExist": true,
  "maxAgeSeconds": 600
}
```