Linux: environment variables not interpreted by `aws configure`

### Describe the bug

Setting environment variables in Linux for an IAM user per the [documentation](https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-envvars.html) and running `aws configure` in the same shell session results in no output.

### Expected Behavior

Per the documentation, the sourced environment variables should be interpreted by `aws configure` in autogenerating the `config` and `credentials` files within the `$HOME/.aws/` directory.

### Current Behavior

Nothing.

### Reproduction Steps

```bash
tee vars <