How can I set up OAuth user-to-machine (U2M) authentication for Databricks account-level operations using environment variables and the Databricks CLI?
To set up OAuth user-to-machine (U2M) authentication for Databricks account-level operations using environment variables and the Databricks CLI, follow these steps:

1. Set the following environment variables:
   - DATABRICKS_HOST: Set this to the value of your Databricks account console URL, which is `https://accounts.cloud.databricks.com`.
   - DATABRICKS_ACCOUNT_ID: Set this to your Databricks account ID.

2. Use the Databricks CLI to log in to your Databricks account with the following command:
   ```
   databricks auth login --host <account-console-url> --account-id <account-id>
   ```
   Replace `<account-console-url>` with the value `https://accounts.cloud.databricks.com`, and replace `<account-id>` with your Databricks account ID.

After running the `databricks auth login` command, follow the instructions in your web browser to log in to your Databricks account. Once you have successfully logged in, the Databricks CLI will generate and cache the necessary OAuth token in the path `.databricks/token-cache.json` within your user's home folder on your machine.

For more information, you can refer to the documentation provided.