export const metadata = {
  title: `${pageNumber} Custom CLI Scripts`,
}

# {metadata.title}

In this chapter, you'll learn how to create and execute custom scripts using Medusa's CLI tool.

## What is a Custom CLI Script?

A custom CLI script is a function that you can execute using Medusa's CLI tool. It is useful when you need a script that has access to the [Medusa container](../medusa-container/page.mdx) and can be executed using Medusa's CLI.

For example, you can create a custom CLI script that:

- [Seeds data into the database](./seed-data/page.mdx).
- Runs a script before starting the Medusa application.

---

## How to Create a Custom CLI Script?

To create a custom CLI script, create a TypeScript or JavaScript file under the `src/scripts` directory. The file must export a function by default.

For example, create the file `src/scripts/my-script.ts` with the following content:

```ts title="src/scripts/my-script.ts"
import { 
  ExecArgs,
  IProductModuleService,
} from "@medusajs/framework/types"
import { Modules } from "@medusajs/framework/utils"

export default async function myScript({ container }: ExecArgs) {
  const productModuleService: IProductModuleService = container.resolve(
    Modules.PRODUCT
  )

  const [, count] = await productModuleService
    .listAndCountProducts()

  console.log(`You have ${count} product(s)`)
}
```

The function receives as a parameter an object with a `container` property, which is an instance of the Medusa Container. Use it to resolve resources in your Medusa application.

---

## How to Run a Custom CLI Script?

To run a custom CLI script, run the Medusa CLI's `exec` command:

```bash
npx medusa exec ./src/scripts/my-script.ts
```

---

## Custom CLI Script Arguments

Your script can accept arguments from the command line. Arguments are passed to the function's object parameter in the `args` property.

For example, create the following CLI script that logs the command line arguments:

```ts
import { ExecArgs } from "@medusajs/framework/types"

export default async function myScript({ args }: ExecArgs) {
  console.log(`The arguments you passed: ${args}`)
}
```

Then, run the script with the `exec` command and pass arguments after the script's path.

```bash
npx medusa exec ./src/scripts/my-script.ts arg1 arg2
```

---

## Run Custom Script on Application Startup

In some cases, you may need to perform an action when the Medusa application starts.

If the action is related to a module, you should use a [loader](../modules/loaders/page.mdx). Otherwise, you can create a custom CLI script and run it before starting the Medusa application.

To run a custom script on application startup, modify the `dev` and `start` commands in `package.json` to execute your script first.

For example:

```json title="package.json"
{
  "scripts": {
    "startup": "medusa exec ./src/scripts/startup.ts",
    "dev": "npm run startup && medusa develop",
    "start": "npm run startup && medusa start"
  }
}
```

The `startup` script will run every time you run the Medusa application.