The `preview` command starts a server to preview your Nuxt application after running the `build` command. The `start` command is an alias for `preview`. When running your application in production refer to the [Deployment section](/docs/getting-started/deployment).
This command sets `process.env.NODE_ENV` to `production`. To override, define `NODE_ENV` in a `.env` file or as command-line argument.
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For convenience, in preview mode, your `.env` file will be loaded into `process.env`. (However, in production you will need to ensure your environment variables are set yourself.)